How Induction Cooking Works

Here's the Basic Idea:

"Cooking" is the application of heat to food. Indoor cooking is almost entirely done either in an oven or on a cooktop of some sort, though occasionally a grill or griddle is used.

Cooktops--which may be part of a range/oven combination or independent built-in units (and which are known outside the U.S.A. as "hobs")--are commonly considered to be broadly divided into gas and electric types, but that is an unfortunate oversimplification.

In reality, there are several very different methods of "electric" heating, which have little in common save that their energy input is electricity. Such methods include, among others, coil elements (the most common and familiar kind of "electric" cooker), halogen heaters, and induction. Further complicating the issue is the sad habit of referring to several very different kinds of electric cookers collectively as "smoothtops," even though there can be wildly different heat sources under those smooth, glassy tops.


As we said, cooking is the application of heat to food. Food being prepared in the home is very rarely if ever cooked on a rangetop except in or on a cooking vessel of some sort--pot, pan, whatever. Thus, the job of the cooker is not to heat the food but to heat the cooking vessel--which in turn heats and cooks the food. That not only allows the convenient holding of the food--which may be a liquid--it also allows, when we want it, a more gradual or more uniform application of heat to the food by proper design of the cooking vessel.

Cooking has therefore always consisted in generating substantial heat in a way and place that makes it easy to transfer most of that heat to a conveniently placed cooking vessel. Starting from the open fire, mankind has evolved many ways to generate such heat. The two basic methods in modern times have been the chemical and the electrical: one either burns some combustible substance--such as wood, coal, or gas--or one runs an electrical current through a resistance element (that, for instance, is how toasters work), whether in a "coil" or, more recently, inside a halogen-filled bulb.

Induction is a third method, completely different from all other cooking technologies--
it does not involve generating heat which is then transferred to the cooking vessel,
it makes the cooking vessel itself the original generator of the cooking heat.

(Microwaving, an oven-only technology, is a fourth method, wherein the heat is generated directly in the food itself.)

How does an induction cooker do that?

Put simply, an induction-cooker element (what on a gas stove would be called a "burner") is a powerful, high-frequency electromagnet, with the electromagnetism generated by sophisticated electronics in the "element" under the unit's ceramic surface. When a good-sized piece of magnetic material--such as, for example, a cast-iron skillet--is placed in the magnetic field that the element is generating, the field transfers ("induces") energy into that metal. That transferred energy causes the metal--the cooking vessel--to become hot. By controlling the strength of the electromagnetic field, we can control the amount of heat being generated in the cooking vessel--and we can change that amount instantaneously.

(To be technical, the field generates a loop current--a flow of electricity--within the metal of which the pot or pan is made, and that current flow through the resistance of the metal generates heat, just as current flowing through the resistance element of a conventional electric range's coil generates heat; the difference is that here, the heat is generated directly in the pot or pan itself, not in any part of the cooker.)

How Induction Cooking Works:

The element's electronics power a coil (the red lines) that produces a high-frequency electromagnetic field (represented by the orange lines).

That field penetrates the metal of the ferrous (magnetic-material) cooking vessel and sets up a circulating electric current, which generates heat. (But see the note below.)


The heat generated in the cooking vessel is transferred to the vessel's contents.

Nothing outside the vessel is affected by the field--as soon as the vessel is removed from the element, or the element turned off, heat generation stops.

(Image courtesy of Induction Cooking World)

(Note: the process described at #2 above is called an "eddy current"; heat is also generated by another process called "hysteresis", which is the resistance of the ferrous material to rapid changes in magnetization. The relative contributions of the two effects is highly technical, with some sources emphasizing one and some the other--but the general idea is unaffected: the heat is generated in the cookware.

There is thus one point about induction: with current technology, induction cookers require that all your countertop cooking vessels be of a "ferrous" metal (one, such as iron, that will readily sustain a magnetic field). Materials like aluminum, copper, and pyrex are not usable on an induction cooker. But all that means is that you need iron or steel pots and pans. And that is no drawback in absolute terms, for it includes the best kinds of cookware in the world--every top line is full of cookware of all sizes and shapes suitable for use on induction cookers (and virtually all of the lines will boast of it, because induction is so popular with discerning cooks). Nor do you have to go to top-of-the-line names like All-Clad or Le Creuset, for many very reasonably priced cookware lines are also perfectly suited for induction cooking. But if you are considering induction and have a lot invested, literally or emotionally, in non-ferrous cookware, you do need to know the facts. (Check out our page on Induction Cookware.)

(And there are now available so-called "inductions disks" that will allow non-ferrous cookware to be used on an induction element; using such a disk loses many of the advantages of induction--from high efficiency to no waste heat--but those who want or need, say, a glass/pyrex or ceramic pot for some special use, it is possible to use it on an induction cooktop with such a disk.)

On the horizon is newer technology that will apparently work with any metal cooking vessel, including copper and aluminum, but that technology--though already being used in a few units of Japanese manufacture--is probably quite a few years away from maturity and from inclusion in most induction cookers. If you are interested in a new cooktop, it is, in our judgement, not worth waiting for that technology.

(The trick seems to be using a significantly high-frequency field, which is able to induce a current in any metal; ceramic and glass, however, would still be out of the running for cookware even when this new technology arrives--if it ever does.)

There is also now the first of the new generation of "zoneless" induction cooktops. These essentially make the entire surface of the unit into a cooking area: sensors under the glass detect not only the presence of a pot or pan or whatever, but its size and placement--and then energize only those mini-elements directly under the cooking vessel. You can thus put any size or shape of vessel--from a small, traditional round pot to a gigantic griddle or grill--down anywhere, in any alignment, and the unit will heat it, and only it (or, of course, seveal "its", as may be).

Quoting AEG's brochure: "The hob senses the size of the pan and only heats the exact area covered by the pan. The Maxi-sense range [uses] ‘flexible sections’ to create an all-over cooking surface. Pans can be placed anywhere on the hob as long as the section marker is covered, eliminating the restriction of traditional specific zones [ = elements]. It does not matter how many pans you have or what size they are, whether it is a fish kettle, a small milk pan, or tagine . . . ."

This technology has only been around since about 2006, and in fairness it must be said that early reports on the prototypes were not all that one might have hoped for; De Dietrich, which is to say the Fagor Group, led then, but the prototype as distributed for testing had problems remembering where things were if they were moved about any, and also with uniform heating. Presumably, the engineers learned from what they heard, because such units are now in production and available (sort of--see the note below). We see, though, that Electrolux is into this technology in a substantial way in some of their induction lines, such as AEG. De Dietrich calls it "Continuum", AEG calls it "Maxi-sense" (as seen at the left). One supposes that soon everyone will have it; we feel it is clearly the future of induction, which in a way is to say the future of cooking, for it won't be so long now before gas for cooking is looked back at in the same way we today look back on coal and wood.

The only lines we know of with this technology are Fagor's De Dietrich--its premium, "upmarket" line--and Electrolux's AEG, neither of which is regularly distributed in North America; there is, however, one distributor in Canada--who apparently also ships to the U.S.--who handles some parts of the AEG line, parts which just recently expanded from two induction units to three, the new one being one of AEG's "zoneless" types, though one of only 6.9 kW total and three zones (yes, Virginia, even "zoneless" units have zones) and a somewhat strange profile, wide but shallow. We have no pricing or availability data.

There is also now such a thing as an induction oven. (It looks as if the usual heating coil on the base of the oven has been replaced by a ferrous plate, which is energized to heat by embedded induction coils beneath it--so any sort of bakeware will work in it.) Expect to see more such things before long.


First, let's define some terms. Energy is a quantity: it's like a gallon of water. In cooking, we aren't really concerned with actual energy--we want to know at what rate a cooking appliance can supply energy. It's like, say, a garden hose: if it can only produce a dribble of water, it doesn't matter to us that if we let it run day and night we could eventually fill many buckets. What we want to know is how forcefully that hose can spray--how many gallons a minute it can put out--because that's what does useful things for us in some reasonable amount of time.

So, in discussing cooking appliances, we normally talk about energy flow rates, which are just like the water flow rates expressed in "gallons a minute"--that is, we want to be able to know at what rate we can pump heat into the cooking process. For gas, energy content (quantity) is traditionally measured in "British Thermal Units" (BTU), and so the flow rate of gas energy is given in BTU/hour. For electricity, energy content is normally measured as "kilowatt-hours" (kWh) and the flow rate is just kilowatts (kW).

(Let's restate that, because it often confuses people, being sort of "upside down". A kilowatt is not a quantity, it's a rate, like "knots" to measure speed at sea--there are no "knots an hour", knots are the speed, and kilowatts are the electrical energy-flow rate. To measure total energy--as, for instance, your electric-supply company does, to know how much to bill you--we multiply the flow rate, kilowatts, by the time the flow ran, hours, to get "kilowatt-hours" of energy. So BTU/hour and kilowatts are both measures of energy flow rates, not of energy itself.)


The energy in gas and the energy in electricity just happen to be measured in different-sized numbers, but they're measuring the same thing. It's like miles vs. kilometers: we can say a place is about 5 kilometers away, or that it's a little over 3 miles away, but the actual distance we'd have to walk or drive is the same. We can easily convert from miles to kilometers if we know how many of one make up the other. Likewise, we can easily convert from BTU/hour to kilowatts (or vice-versa). There are just about 3,400 BTU to a kWh--or, more exactly, about 3,413. (Keep in mind that a kilowatt is 1,000 watts: 1 kW = 1000 W).


Superficially, then, comparing cooking technologies looks easy: can't we just look at the rated kW or BTU/hour of a cooktop, and simply convert one kind of measure to the other to compare them? Nope. The complication is that the various technologies are not all equally effective at converting their energy content into cooking heat; for example, gas delivers little more than a third of its total energy to the actual cooking process, while induction delivers about 85 to 90 percent of its energy.

That means that if we have a gas cooker capable of putting out X BTU/hour, converting that X to kilowatts does not tell the story--because a lot more of that X is wasted energy that doesn't do any cooking than is the case with induction. To truly compare the cooking power of a gas cooker and an induction cooker, we indeed need to first convert one measure to the other, say BTU/hour to kilowatts; but we then need to slice off from each unit's nominal output the amount that does not get used for cooking.

(Think again of garden hoses: if we have two hoses and each is getting, say, 5 gallons a minute pumped into it by the water tap it's screwed onto, are they the same? Not if one has a pinhole leak while the other has a gaping rip. The amount of water that comes out the nozzle to do whatever we need done will differ drastically from one to the other. Induction cooking has a pinhole leak, maybe 10% to 15% of the raw energy it takes being wasted; gas cooking has the whacking great rip in it, the average unit wasting over 60% of the raw energy it consumes.)

So, to see how induction compares to its only real rival, gas, we have to make the following calculation:

BTU/hour = kW x 3413 x Eind/Egas

That last term there--Eind/Egas--is simply the ratio of the two methods' real efficiencies: Eind is the energy efficiency of a typical induction cooker and Egas is the energy efficiency of a typical quality gas cooker.
abstract mathematics design

The snag comes when we try to find reliable figures for those efficiencies. It is remarkable how much misinformation there is (especially on the internet), largely from well-meaning but ignorant sources who do not understand the issues, or are simply repeating what they read elsewhere (from someone else who does not understand the issues). For example, the energy-efficiency values quoted by various induction-cooker makers range from a low of 83% to a high of 90%, while values given for gas cooking run, depending on the source, from 55% down to as little as 30%, nearly a 2:1 ratio.

Fortunately, in the last few years some standardized data from disinterested sources have become available, so we no longer have to rely on figures from parties with an axe to grind. The U.S. Department of Energy has established that the typical efficiency of induction cooktops is 84%, while that of gas cooktops is 40% (more exactly, 39.9%)--figures right in line with the range of claims made for each, and thus quite believable.

Using those values (and sparing you the in-between steps), we can say that gas-cooker BTU/hour figures equivalent to induction-cooker wattages can be reckoned as:

BTU/hour = kW x 7185

It is worth noting that the testing method that established the induction data used, in essence, a slab of ferrous metal as the "vessel". It reliably established what might be called a "baseline" efficiency, and that is why we use it throughout in evaluating energy equivalencies. It remains as a possibility that particular items of induction equipment--and, for that matter, of cookware--may be a bit more or less efficient than the baseline. There are at least plausible reports that some makes, coupled with some items of cookware, can achieve true efficiences close to 90%. On this site, we do not use that value because we do not yet know of any definite, reliable data, but you should keep it clear in your mind that when we discuss the gas heating-power equivalencies of induction units, we are using what should be considered rather conservative numbers; chances are that many induction units are actually somewhat more powerful (in BTU/hour equivalents) than we set forth.

In fact, Panasonic states for several of its units that efficiency is 90%, noting that: Heating-efficiency measurements were taken based on standards of the Japanese Electrical Manufacturers' Association and using a Panasonic standard enamelled iron pot. Also: a University of Hong Kong research product showed induction efficiencies from 83.3% to 87.9%, numbers clearly in line with 84% as a minimum and 90% as possible.


So How Much Power Is What?

Perhaps the most useful way to use that conversion datum is to see what good gas-cooker BTU values are and work back to what induction-cooker kW values would have to be to correspond. But what are good gas-cooker BTU values? Here too, opinions will vary. As a sort of baseline, we can look at what typical mid-line gas ranges look like. As numerous sources report, a typical "ordinary" home gas range will usually have its burners in these power ranges, give or take only a little: a small burner of about 5,000 Btu/hour; two medium-level burners of about 9,000 Btu/hour; and (depending on width, 30 inches or 36 inches) either one or two large burners of anywhere from 12,000 to 16,000 BTU/hour
woman cooking over open fire

When one moves from stock home appliances up to the deluxe level (sometimes called "pro", though ironically the warranties for such units expressly forbid commercial use), gas ranges and cooktops naturally become more powerful. On these, burner powers run up to 18,000 BTU/hour or thereabouts (one highly regarded specimen of this class has four 15,000-BTU/hour burners and two 18,000-BTU/hour burners). One expert source remarked of such gear: Most commercial-style home ranges offer 15,000 BTUs per burner, which is perfectly adequate for most at-home cooks. You won't always need all that heat, but if you want to caramelize a bell pepper in seconds, or blacken a redfish like a pro, well, you'll need all the heat you can get. My advice: Go for the big-time BTUs (which, in the tests he was discussing, was that 18,000 BTU/hour level).

So let's summarize by showing representative gas-power levels and their induction-power equivalents (remember, calculated quite conservatively):

Typical home stove:
small: 5,000 BTU/hour gas = 0.70 kW induction
medium: 9,000 BTU/hour gas = 1.25 kW induction
large: 12,000 BTU/hour gas = 1.70 kW induction; or 15,000 BTU/hour gas = 2.10 kW induction

Typical "pro style" stove:
medium: 15,000 BTU/hour gas = 2.10 kW induction
large: 18,000 BTU/hour gas = 2.50 kW induction

(Even for wok cooking, the most power-hungry kind there is, experts consider 10,000 BTU/hour good and 12,000 BTU/hour "hot".)

So how do actual real-world, on-the-market induction cooktops stack up against gas?

It's an almost comic mismatch. Sticking to build-in units (as opposed to little free-standing countertop convenience units), it is difficult, perhaps by now impossible, to find a unit with any element having less than 1.2 kW power--which puts the smallest induction element to be found equal to the average "medium" burner on a gas stove. The least-expensive 30-inch (four-element) induction cooktop has:

a 1.3-kW small element (between 9,000 and 9,500 BTU/hour),
two elements of 1.85 kW each (well over 13,000 BTU/hour), and
one element of 2.4 kW (over 17,000 BTU/hour).

The least-expensive 36-inch (five-element) induction cooktop has:

a 1.2-kW small element (8,500 BTU/hour),
a medium element of 1.8 kW (13,000 BTU/hour),
a larger element of 2.2 kW (16,000 BTU/hour),
and two elements of 2.4 kW (over 17,000 BTU/hour).

The very highest-power gas burner to be found in the residential market is 22,000 BTU/hour, and that's a sort of freak monster, whereas a 3.6-kW and 3.7-kW element--which is around 26,000 BTU/hour of gas!--is found in many induction cooktops. (Moreover, the elements on some induction units can share power with one another, so that if not every element is already in use, a given one can be "boosted" beyond its normal power level, for uses such as bringing a large pot of water to a boil, or pre-heating a fry skillet.)

So, in sum, induction is not "as powerful as gas"--it's miles ahead.

(There is, incidentally, a lesson there: even really serious cooking does not, save for perhaps a few specialty cases, require stupendous amounts of power, and you should not be seduced into choosing between units sheerly on the basis of the maximum available firepower per element. For one thing, most units of the same size have total maximum unit capabilities that are nearly identical: the differences lie in how they distribute that total among the unit's elements, which are invariably four on a 30-inch-wide unit and five on a 36- inch-wide unit. When a pro tells you that really "big-time" power is the equivalent of around 2.5 kW of induction, you should ask yourself whether getting elements with significantly more power than that really should be a major consideration in your decision-making process.)

(There is a much more substantial discussion, which we strenuously recommend anyone at all interested in induction-cooking equipment read, on our site page titled Kitchen Electricity 101).

So now that you know how induction works, and how--at least in raw cooking power--it compares with gas, let's go on to examine in more detail all the Pros and Cons of Induction Cooking.

Sources: http://theinductionsite.com

Fix it when the Sun Shines - Photovoltaics

In our last post we expressed the need to find an energy resource which could solve our energy problems not only by providing power but being clean as well. And some say the obvious answer is the sun. And here is a good reason for this; if we can utilize 0.1% of the total energy absorbed by the earth over the course of a year from the sun, we can produce enough energy to eclipse the current energy generation by 10 times! The energy from the sun is mapped in the figure below.

Solar energy has been harnessed by humans since antient times and the technology is still evolving. Other renewable resources including wind, wave power, hydroelectricity and biomass wich are most of the renewable energy resources on the planet are secondary derivatives of the sun. A single post will definately not be enough for this, so here to a sunny summer.

Photovoltaic Cells

Photovoltaic cells translate solar energy to electrical energy because of the photovoltaic effect. The photons (packets of energy) in sunlight include energy corresponding to the diverse wavelengths of sunlight. When light strikes upon a photovoltaic cell these photons may pass through, be reflected or absorbed by the panel. On absorption of photons the energy contained in the photon is redirected to an electron contained in the atom of the semiconductor material the photovoltaic cell is made of.

General photovoltaic cells contain two layers of silicon wafers doped with phosphorous and boron. The layer doped with phosphorus (called the n-Layer) contains excess free electrons and the layer doped with boron has a tendency to attract electrons (called the p-Layer). Though neutral individually when stacked on top of each other a “p-n junction” is formed due to transfer of electron from the “n-Layer” to the “p-Layer” creating a barrier to prevent more electrons from moving between the layers and also reversing their polarity. This leads to poles, negative for the “n-Layer” and positive for the “p-Layer”. When placed under the sun photons in light strikes electrons in the “p-n junction”, energizing them and knocking out the atoms, thus attracting the electrons to the positive n-layer and repelled by the negative “p-layer” and hence generating electricity.

The simplest photovoltaic cell can produce much less energy as it does not fully utilize the entire spectrum of light. Photovoltaic cells are distinguished between each other by the type of the crystal used. As can be seen from the table below, Multi-junction cells boast the highest efficiencies in photovoltaic technology and are best with concentrators, however due to their expense Multi-junction are mostly used in aerospace operations.

Multi-junction photovoltaic cells

Multi-junction photovoltaic cells offer high-performance scientific development passageway for low cost electricity generated by concentrating sunlight. These photovoltaic cells consist of several thin films/layers that allow them to confine more solar spectrum to translate to electrical power. Semiconductors have a distinguishing band gap energy that allows absorption of light (electromagnetic radiation) very efficiently for a certain colour (spectrum portion). These semiconductors are needed to be cautiously selected to take up most of the spectrum of sunlight, leading to higher electricity generation.

Multi-junction PV cells use numerous layers of PV films, made of differing alloys of III–V semiconductor material. The band gap of each layer can be adjusted to allow the absorption of a specific band of electromagnetic radiation from the sun. However, it should be ensured that each layer is lattice matched to the other. The Layers are aligned optically in series with the largest band gap material on top. The top layer receives entire range, the photons with band gap higher than the layer are absorbed and the rest is channelled through to the lower layers.

The best know and available Multi-junction cells for terrestrial use are produced by “Spectrolab” called Ultra Triple Junction (UTJ) solar cells consisting of In0.56Ga0.44P / In0.08Ga0.92As / Ge layers shown in the figure above, on test have shown to provide efficiency of 40.7% with a concentration level of 240 suns and a general efficiency of 24.3 %.

Sources:

Wikipedia, need.org, Us Department of Energy, solarserver.de, Spectrolab

- Energy Engineers to the rescue

- OSSA

What the Future Demands from an Engineer

Through our years of development we have reached a stage where we are threatened by our own ingenuity in the past. It may be said that, it was the engineers who doomed the world with the inventions why should they should be trusted again? Well you know what, you have no other choice.

We argue as to why we can't go back to the way we had been living before, downgrade ourselves to save the planet, but as far as I know, we are not good for settling for less, I myself am not. We enjoy the convenience the development has brought about, and in many cases we can't live without them, we have been molded into this system as such. However, its not only the matter of convenience. We all acknowledge that we are living in a dying world, we have reached a stage where we might have to go back to being cavemen to actually save the planet. We are not only looking at retracing our footsteps but reversing the effects on the planet. To explain in the form of an example, we have released so much carbon-dioxide into the atmosphere, its time to suck it in.

Area of focus: ENERGY

Anything we do, we need energy; this is one of those things that has become an intricate part of our lives and we cannot do without. As technology advances, so does our demand for energy as can be seen in the figure below. So what is the problem? just build power plants, and the problem is solved? Not quite.

The source of energy is a big concern, though oil is a stable industry it is running out, so is gas and causing harm to the environment, nuclear energy is highly unstable, renewable energy is underdeveloped, weather dependent. The need is hence for a substitute for oil for the generation of electricity and for transport. We have the sources, but do we have the technologies to tap into these sources?

Energy utilization defines all the valuable requirements for life in today's world; food, the air we breathe, and the most precious, energy also plays and will play a huge role in is for the production of water in most parts of the world. There are very few sources of fresh water left and in arid areas (like deserts) desalination is required which uses up a lot of energy. The figure below shows the water resource distribution around the world.

Sources in focus: ALTERNATIVE ENERGY SOURCES

Alternative energy sources defines any source of usable energy that can be used to replace fuel sources in this case Petroleum without its undesired consequences. They can be further categorized into Renewable (which utilize sources such as sun, wind, water and other naturally available energy sources), Nuclear (including Fission, Fusion), Hydrogen and Fuel Cell technologies. These technologies are relatively, and in some cases far cleaner, than the conventional technologies. However they are riddled with their own problems.

Over the course of our posts we shall try to highlight these technologies, the problems associated with these technologies and showcase the engineering solutions proposed and being worked on to solve these problems and may be leave a few suggestions of our own.

Photos:
whyfiles.org ,eia.gov,islamicity.com

- Energy Engineers to the rescue
- OSSA

The New Solar Home

Product Description

Authors Dave Bonta and Stephen Snyder of USA Solar Stores illustrate exceptional homes that are groundbreaking not only in their use of renewable energy but also in their commitment to recycling and repurposing materials used in construction and reducing the impact on the surrounding environment through sensitive building methods. With details on why these homeowners decided to go solar and how having a solar home can save money in the long run, these solar beauties are sure to inspire homeowners to create or remodel their own solar sanctuaries.

Dave Bonta writes about alternative energy and sustainable living for Green Living, Back Home Magazine, Alternative Energy Retailer, and the Vermont Guardian. He is a frequent speaker at major green energy conferences and lives in Perkinsville, Vermont.

Stephen Snyder, communications director for USA Solar Stores, is a freelance writer who lives in Perkinsville, Vermont.

Shows how solar technology can be stylishly utilized in various home sizes and locales

From the Inside Flap

The New Solar Home features a variety of solar dwellings of different sizes and locales, from 1,600 to 4,000 square feet or more, and in large cities, suburbs, and remote rural sites. From an umbrella home in beautiful California and a stunning luxury condominium in New York to a Chicago brownstone-style home in Illinois and a pueblo-style gem in the foothills of Santa Fe, solar homes have come a long way from the PV-clad creations of the 1980s.

Bonta and Snyder successfully demonstrate that today's solar homes are attractive, good financial investments, and comfortable places for daily living. These exceptional homes are groundbreaking not only in their use of renewable energy but also in their commitment to recycling and repurposing materials.

Get details on why these homeowners decided to go solar, and find out how having a solar home can save you money in the long run. Whether you're looking to build a new home or simply remodel an existing one, the solar beauties within these pages are sure to inspire you to create your own solar sanctuary.

Dave Bonta, President and Founder of USA Solar Stores, the largest renewable energy retailer in the Northeast, has written about alternative energy and sustainable living for Green Living, Back Home Magazine, Alternative Energy Retailer, and The Vermont Guardian. Bonta has studied renewable energy and energy efficiency for more than twenty years, is a frequent speaker at major green energy conferences across America, and is a tireless advocate for green living. He lives in Perkinsville, Vermont.

Stephen Snyder is also the author of The Brewmaster's Bible (HarperCollins), The Beer Companion (Simon & Schuster), and The Brewmaster's Recipe Manual. He lives in Vermont.-
If you want to buy this book click.

www.amazon.com

"Schaum's Outline of Electric Circuits"

Joseph A. Edminister, Mahmood Nahvi, "Schaum's Outline of Electric Circuits"
McGraw-Hill Trade | 1995 | ISBN: 0070189994 | 400 pages | PDFs |

This third edition of Elecric Circuits provides all-new chapters on operational-amplifier circuits, waveforms and signals, two-port networks, Fourier transforms, and circuit analysis using Spice and Pspice software.

It also gives students with a solid foundation and background for engineering and electronics studies. The many problems solved step-by-step, and the hundreds more with answers, help reinforce learning and prepare students for top results on exams and in practice

Size : 66.3Mb

Download Link 1
Download Link 2

Volcano erupts in Chile

The eruption of the Puyehue volcano in the Andes mountains of southern Chile last weekend provided some spectacular images of the force of nature. Ash covers the landscape and thousands of people were evacuated from the surrounding rural communities. The volcano, which hasn't been active since 1960 when it erupted after an earthquake, sent its plume of ash 6 miles high across Argentina and toward the Atlantic Ocean.

A plume of ash, estimated six miles (10km) high and three mile wide is seen after a volcano erupted in the Puyehue-Cordon Caulle volcanic chain, about 575 miles (920 km) south of the capital, Santiago June 4. (Ivan Alvarado/Reuters)




A helicopter flies over smoke and ash rising from the Puyehue-Cordon Caulle volcanic chain near Osorno city in south-central Chile June 5. A volcano dormant for decades erupted in the Puyehue-Cordon Caulle volcanic chain in south-central Chile on Saturday, belching an ash cloud more than 6 miles (10 km) high that blew over the Andes and carpeted a popular ski resort in neighboring Argentina. (Ivan Alvarado/Reuters)

A member of the media walks along a road covered with ash from Chile's Puyehue-Cordon Caulle volcano chain near the Cardenal Samore border pass between Argentina and Chile, June 7. (Ivan Alvarado/Reuters)



A plane is seen covered in volcanic ash at San Carlos de Bariloche airport, southern Argentina June 7. The wind carried volcanic ash across the Andes to Argentina resulting in the closing of six airports, and the cancellation of flights in the capital city. (Alfredo Leiva/Associated Press)




A view is seen of the ash plume above the Puyehue-Cordon Caulle volcano chain near Entrelagos June 5. (Carlos Gutierrez/Reuters)



An aerial picture showing the cloud of ash billowing from Puyehue volcano near Osorno in southern Chile, 870 km south of Santiago, taken on June 5. (Claudio Santana/AFP/Getty Images)

boston.com

Heaviest Motorcycle in the world

Have you ever had a bike that's so great, so that it will carry 80-10 adults seen at once? Do you know what is the latest greatest motorcycle in the world after Guinness World Records? The answer is here, this is the heaviest and largest motorcycle in the wold ever created

Tilo Niebel and his Monster Bike

The huge wheel was built by a team led by Tilo Niebel of eastern German village of Zillah. To complete his goal to make the greatest motorcycle in the world. Tilo uses a motor of the Soviet tank T55, which has 800 hp. The bike was assembled by hand and it took several weeks to build it.


The total weight of the monster bike is almost 5 tons and a total length from tail to head is 5 ½ feet. According to the Guinness Book of Records, the official weight of the bike is 4740 kilograms (4.7 tonnes). The shell of an old Soviet car and the engine was built by a Russian T55 tank taken -1986 model

To complete the look of the monster wheel was Tilo and his team, the Russian military centers. The frame, springs were, controls, propulsion, landing gear and wheels from the military scrap taken. Information about where he bought the military tank is classified, but the tank's engine and is capable and the most important thing It `s work

The biggest motorcycle in the world, the weights 5 tons8 heaviest motorcycle in the world
Last, the motorcyclists' s is 2 meters high. It is one of a kind and rare. The total price for the construction of the wheel is not known, but I think it is more than a 100k.

Before this bike, the largest and heaviest motorcycle in the world with Greg Dunham's motorcycle was titled, is on his motorcycle only 6,500 pounds, or about 2.5 tonnes..


interestingworldfacts.com

Interesting facts of Albert Einstein

He is a genius. This planet does this guy as one of the most brilliant people on Earth. In 1999, TIME Magazine awarded this wild hair guy as a person of Century.However, this man is not Superman. His life was not filled with roses and jasmine. His life was full of struggle, the sights and is 11 interesting facts about Albert Einstein, you never know.

1.Troubles of Speaking

In his early years, Albert Einstein's parents as his son has a mental disability problem. He was to speak slowly, and he had difficulty talking with his friends around his neighborhood

2.Has bad memories.

Although he is super intelligent, he has a bad memory. He barely remembered his wife's and son's birthday. When he was alive, find his neighbors often Einstein to Princeton area around his home.


3.Bad in Science subject


When he was 17 years old, he wanted to enroll the Federal Polytechnic, and on this the first time he failed the entrance examination to the answer. He was bad at geography, history, language, and it was a major reason why he had to try next year in power at this school.

4. Bad Writing in English

English is his second language, and he did not write much English literature, because his English spelling was bad. He could not speak English, but a great feeling it would not have happened if someone asked him to write it on paper

5. Rock star of the theory of relativity

When he found the theory of relativity, he was so famous, so that each time he met a man on the street, they could stop him and delivered him to the theory of relativity. He answered many times until he felt bored and tired. Finally, when asked his theory of relativity, people again, he would reply: "I'm sorry I'm always mistaken for Professor Einstein"

6. Not dressed properly


He had a big toe when he was young and his toe would make a hole in his sock every time he wore it. He stopped to carry a pair of socks and he refused to wear a nice dress for anyone since then, although he had to meet the President of the United States.

7.Israel tried to elect him as president

During World War II, Israel received its independence and the country tried to Einstein to choose as their president. In that time, Einstein rejected this proposal, and he said "he had no head for problems."

8. He did not get physics Nobel prize in person


He personally was on tour in Japan, the time and do not get it, the badge of honor. As a doctor he had a great style.

9. Unknown last word

When he was dying, accompanied by a good nurse him but unfortunately they did not understand German.Einstein spoke in German when he died and his final message was revealed until the end of time unknown.

10. Man of Science who hate science fiction

When he was alive, he said to the public that he did not believe in Time Machine, he did not believe in flying saucers or UFO believe, and he also said that "distorted science fiction pure science."


11.His Brain ended up in a trunk


He died in 1955 and he had a treasure behind his head, he could not bring with him. His brain was so valuable, so that Einstein did not go with him.Thomas decided Stoltz Harvey, a man who has Einstein's autopsy to be examined Einstein's brain from the head did. He did the job without notice, Einstein `s family. Einstein's son Hans Albert, finally knew that his father died 43 years later brainless.

interestingworldfacts.com

Some Facts About China

Today, China is not the same as we knew China 60 years ago. China has changed to one of the wealthiest nations in the world, without asking any democratic system that the U.S. has become widespread eagerly around the world. In this post I would like to summarize view interesting fact about China. I hope you like it

1. The China of today was after the end of World War II founded. Nationalists and Communists united to throw away to Japan from their land. View years later, sparked a civil war and was the nationalist-communist existence and Mao Zedong as the leader of the Communist Party took full control of PRC (People's Republic of China) for over or to 1 October 1949.





3. China is known as world’s industrious nation. The number of workforce is estimated over 800 million people and in 2009-2010 alone, those numbers of people had produced:
22,300,000,000,000 cigarettes

619, 2 million mobile phones from various brands

13, 2 million tons of Sugar

13, 8 million unit motors

59, 3 million fridges

67,6 million LCD TVs

4.Chinese goods and many large percent of it is exported abroad. In 2009, China had exported U.S. $ 28,000,000,000 rated shoes, U.S. $ 39, 6 billion and U.S. $ self phones estimated 107, rated one of men, women and children's clothing. Some of the running shoe, even phone and clothing industry are imitations.



5. United States is the 2^nd biggest country that welcomes Chinese goods. Every year, US pay $220,000,000,000 in exchange of all that goods

6. View interesting facts about food in China:

More than 300 million Chinese are peasants China supplies 26% of world rice demand or estimated 193 million tonnes In 2008, all people had eaten in China 130, 7 million tons of rice Are killed each year around 300 million of turtles in the residential, made and served on a plate or bowl


7. View interesting facts of China’s military:

-The number of Active army is 3, 4 million personnel and reserve army is 1, 2 million personnel

-China’s Military budget is the 2nd largest in the world after US

-China has 100-400 nuclear weapons and their ground forces are backed up with 7,500 battle tanks

-China has 2,024 aircrafts following Russia with 2,832 aircraft and US with 5,550 aircraft.

8. China is strictly punished corruptors, tax fraud, narcotics smugglers, arsonists, illegal fundraisers and counterfeiters. In 2008 alone, 72 percent of world’s executions took place in China. Most of them ended with bullet in their head.



9. Chinese mafia or Triad sits on the 2^nd position of world’s largest number. Triad has more than 250,000 members while Russia has 100,000-500 thousand members. Following China, Yakuza from Japan sits on 3^rd position with 86,000 members and than Italian Mafia called Cosa Nostra at 4^th position with 4,000 members.

Vernier Calliper

The meter scale enables us to measure the length to the nearest millimeter only. Engineers and scientists need to measure much smaller distances accurately. For this a special type of scale called Vernier scale is used.




Vernier Calliper

The Vernier scale consists of a main scale graduated in centimeters and millimeters. On the Vernier scale 0.9 cm is divided into ten equal parts. The least count or the smallest reading which you can get with the instrument can be calculated as under:

Least count = one main scale (MS) division - one vernier scale (VS) division.

= 1 mm - 0.09 mm

= 0.1 mm

= 0.01 cm

The least count of the vernier

= 0.01 cm

The Vernier calliper consists of a main scale fitted with a jaw at one end. Another jaw, containing the vernier scale, moves over the main scale. When the two jaws are in contact, the zero of the main scale and the zero of the vernier scale should coincide. If both the zeros do not coincide, there will be a positive or negative zero error.

After calculating the least count place the object between the two jaws.

Record the position of zero of the vernier scale on the main scale (3.2 cm in figure below).



Principle of Vernier

You will notice that one of the vernier scale divisions coincides with one of the main scale divisions. (In the illustration, 3rd division on the vernier coincides with a MS division).

Reading of the instrument = MS div + (coinciding VS div x L.C.)

= 3.2 + (3 x 0.01)

= 3.2 + 0.03

= 3.23 cm

To measure the inner and outer diameter of a hollow cylinder or ring, inner and outer callipers are used. Take measurements by the two methods as shown in figure below.

www.tutorvista.com/

How to be an Electrical Engineer

Electrical engineers design, test and implement the use of a variety of electrical devices. If you are math and science, enjoy are technically minded, and have a strong attention to detail, then you might like to become an electrical engineer.

Electrical engineer their knowledge of computer science and mathematics of electronics in a wide range of applications. Electrical engineers work in a wide range of industries. You could include design and test a range of equipment, electric motors, lighting, electrical machinery, pipes, aircraft and radar, to name a few. Most electrical engineers specializing in a specific area, such as computers or car industry.

Education requirements for an electrical engineer:


During high school to try and get good grades in math and science, if you want to become an electrical engineer. If your school has a technology theme, then you should take this also. Computer science is also a good choice of subject, because most technical work is based on computer applications in those days.

After high school, look for a college that has a strong engineering program. To become an electrical engineer, you must have at least four years, all electrical engineering degrees. Good electives include economics, mathematics and scientific subjects.

Most universities run an electronics club, or something similar. Membership in one of these clubs is a great way to build experience by working on projects. Build such a lot of colleges and race solar-powered cars. Likewise, if the opportunity to support a research project to get, this is a good option and a dissertation or research project in your last year.

With a Bachelor's degree, you will be qualified for most entry-level job as an electrical engineer. Some research jobs will continue to the graduate school, where you achieve a master's or doctorate in another field. This would also qualify you in the Engineering Faculty jobs to work at a college.

A good source for information about a career in electrical engineering is the IEEEUSA site.

Electrical Engineer Job Description:


An electrical engineer designs new products, the electronics and circuits exist, and to improve existing products. They run stringent tests on products in development to ensure that they function properly and are safe for use.

Electrical engineers design cars, wiring and lighting, robotics, generators, GPS systems and aircraft electronics, to name a few. Most electrical engineers will specialize in a specific type of work.

An electrical engineer in the private sector, the work environment is usually within an office or sometimes a factory or plant. For the most part they work a forty hour week, in some cases they may have to work overtime to meet a deadline.

Some engineers are working on site, or work with research and monitoring equipment. This hands-on items to bring challenging and unusual hours. They are common in power plants, or in a car factory, for example.
Here are some of the functions of electrical engineering:

* Develop new ideas * Implementation of new ideas * Improvement of current systems * Test new products * Fix problems with products * Ensure the work meets safety requirements

If you are an engineer, which offers its services directly to the public work, certification in all fifty states is required.

Electrical Engineer Salary and Career Paths:


When you first got an electrical engineer, you will be working for a year or two under the supervision of an experienced colleague. After you gain some experience, you will be given more responsibility. They could help others to start their projects and then later on, head up your own projects.

You can progress to train engineers, or to a head engineer in your area. Some engineers progress to sales or management positions within the industry they work.

The median wage of an electrical engineer is $ 83,000 a year. There are good career prospects for qualified engineers, and there's average growth forecast for the coming years.
Some similar roles to that of electrical engineering are:

* Aerospace Engineer
* Civil
* Industrial Engineering
* Mechanical Engineer
* Computer Programmers
* Electricians

A sense of curiosity, an eye for detail and a good head for mathematics, everything is good moves when you become an electrical engineer. Although the growth in this sector is average compared to other professions, they should have no problems with qualifications securing lucrative employment.

Electrical Engineering Jobs

While lots of people might have a preconceived thinking about electrical engineering jobs and also what they entail, most do not understand that electrical engineering jobs encompass a lot more than jobs working with electricity. Electrical engineering is a wide field that consists of a variety of professions, and there are a number of electrical engineering jobs in various distinct fields. Electrical engineers usually deal with electricity as energy, and they also own electrical engineering jobs in grounds that harness the power and grow solutions to completely use electricity for a variety of wants.



The variety of electrical engineering jobs consist of working with cell phones, the introduction of electrical models in vehicles, wiring the electrical systems in buildings, and working to keep large scale power systems working effectively. Several electrical engineering jobs may even include working on intricate manage systems for fighter jets, industrial airplanes, as well as area shuttles.

Usually, electrical engineering jobs need which engineers work with electrical systems on quite a big range, but one branch, electronic engineering, deals with the electrical models on a small size. Normally, a lot of these electrical engineering jobs involve dealing with small integrated circuits and computer systems. Whether an electrical engineer deals with tiny electrical systems or large electrical systems, there are several different electrical engineering jobs available.

However you will find currently a lot of electrical engineers all over the world, there are many different electrical engineering jobs that are open and need to be filled up. Growing to be an electrical engineer takes a lot of education and learning, dedication, and effort. And so there are insufficient electrical engineers to load all the electrical engineering jobs that are available. If you are looking for any great career prospect, you might want to think about becoming an electrical professional. The spend on electrical engineering jobs is outstanding, with almost all electrical engineers earning more than $50, 000 every year, as well as some producing a lot more than that.

If you wish to become an electrical engineer so you can help to fill up the open electrical engineering jobs that are offered, you have got to attend college and get a degree in anatomist. Each science and math will be extremely important to becoming an engineer, so it’s important that your levels are great in both disciplines. While there are many electrical engineering jobs available, the discipline is usually extremely competitive, so you will need to make sure you own fantastic grades while you are studying to get an electrical engineer. Employers want engineers which might be dedicated, smart, in addition to revolutionary so as to take their know-how and apply it to their job.

Whether or not you are searching for electrical engineering jobs working with battleships as well as fighter jets, or you are researching for jobs that deal with cellular phones and computer systems, there are many jobs that are available. Obtaining an electrical engineering degree could start a host of electrical engineering jobs that you could pick from, if you function hard and excel as a university student. Getting your education as an electro-mechanical engineer is only the beginning of where it is possible to go in that discipline of electrical engineering.

http://www.zimbio.com/