describe and give the principle of hot air oven.?
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Hot air oven circulates the heat around the food being baked. A standard oven , heat rises from the bottom.
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Hot air rises.\n\nThe tiles are on the floor. Ceramics can conduct and retain heat, but not so easily when that heat isn't being piped straight through them.
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It is formed by heat pressure
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If enough moisture is evaporated from the food then it will eventually combust. I'd say a slice of pizza for 15 minutes should do it.
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The basics....\n\n1. Burn something\n2. Whatever is burnt, boils water that turns into steam.\n3. The steam is used to turn turbines \n4. the turbines generate electricity\n\nFor a more detailed answer, go to howstuffworks.com or wikipedia.
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If you don't want to wait that long try these easy steps:\n(note:  I do this all the time)\n\n1.  place between sheets of wax paper, leave space between them\n\n2.  now that you have them in the wax paper place them inside tin foil.\n\n3.  place in your preheated oven (200 degree or 250 in high altitudes) for 4 hours.\n\nRemove, and there you go.
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heat the pure gas in a sealed tube in absence of air. it breaks up into its components. you've got solid yellow sulphur.
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Hmm, the basic principle is that it excites the water molecules in food which creates heat energy. Don't know about putting a radioactive element in there...
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As a general rule, warm air rises and cool air sinks\nit expands and becomes lighter as the molecules of air move farther apart
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Start with 2 eggs water flour and an oven. Oh a nuc I thought you said cake
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Stages of Air Separation\nFirst stage is filteration of air\nAll the unwanted ingredients are removed from the air mixture by filteration or chemical absorption. These unwanted particles might damage the equipment.\n\nSecond stage is compression of air\nThe filtered air is then compressed to almost 5.5 bar. A good amount of energy is needed for the efficient running of the compressor.\n\nThird stage is cooling of the compressed air\nWhen cooled air is compresses it generally generates heat and becomes warm. The air needs to be cooled down and so is passed under a shower of cold water using a direct cooler.\n\nFourth stage is the use of heat exchangers\nIt is expensive to cool large amounts of air, so the cold temperatures achieved in the plant are conserved using heat exchangers. These are pieces of equipment that allow heat to pass from one fluid to another without the fluids mixing.\n\nFifth stage is liquification of cooled gas\nThe air cooled expands and gets more cooled when placed in a separation column. The gas slowly turns to its liquid state.\n\nSixth stage is pre purification of air mixture\nAir mixture may contain traces of argon, carbon dioxide and hydrocarbons. These traces can be removed using pre purification units where these are further liquified and they freeze out. They become solid and can be easily removed.\n\nSeventh stage is separation of nitrogen and oxygen\nThe liquid mixture of products trickles down to meet the rising stream of gas. The liquid collects on the trays of the column and is penetrated by the vapor bubbles from beneath. Oxygen having higher boiling point condenses out of the stream of gas. Nitrogen evaporates due to lower boiling point.\n\nEight and the final stge is obtaining pure nitrogen and oxygen\nGaseous nitrogen collects at the top of the separation column, while liquid oxygen collects at the bottom of the column. The oxygen at the bottom is vaporized, while nitrogen in liquid form is introduced at the top of the column. This process is continued as long as is required to reach the desired level of purity.
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food water air reproduction
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for radiation - how about someone sitting under the sun? Radiant energy is what heats you from the sun.\n\nFor convection (you seem to change your mind if you want convection or conduction info) you could think in terms of how a convector heater works - the warm air circulating the heat around the room. Convection also applies to liquids too - think of the water in the kettle and the water currents inside making all of the water heat more-or less together.\n\nFor conduction, how about a saucepan sitting on top of a cookers' hotplate?\n\nHeating by radiation is through infrared heat - from the sun, from a light bulb - even a bonfire but that can also be from convection too. Think in terms of "heatwaves" with radiation perhaps.\n\nConduction of heat is when two surfaces of dissimilar temperature are brough together. Some of the heat will travel by conduction (touching) to the cooler object.
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********************************************************\n\nIf you ask me, one of the cleverest parts of a microwave oven is the door. It lets you see into the oven to make sure your potato isn't about to explode, yet keeps your face from being cooked off by microwaves in the process. It accomplishes this remarkable feat with a metal mesh—basically a sheet of metal with a regular pattern of small holes drilled or punched in it. This, along with the metal material of the oven cavity itself, forms a sort of reverse Faraday cage. A Faraday cage is a metal enclosure that normally keeps electrostatic fields and RF (radio frequency) radiation from getting in, but in the case of the oven, from getting out.\n\nA solid sheet of metal would be the most efficient at containing RF, but since you can't see through metal (unless you happen to be Superman), a compromise must be made. How much RF escapes through the mesh depends largely on two factors: the wavelength of the radiation in question, and the diameter of the holes. (For you picky types, the conductivity of the mesh material has a slight but negligible effect, as does the shape of the holes, among other things.) The shorter the wavelength of the RF, the smaller the holes need be to block the radiation. Microwave ovens operating at 2450 MHz emit radiation with a wavelength of about 12 centimeters, and the holes in the mesh of the door are typically on the order of 1-2 millimeters in diameter. Since the holes are small compared to the wavelength of the microwaves, little radiation can leak out. There are also mesh screens on the sides of the oven cavity, one to protect the oven light while allowing it to shine into the cavity, the other to permit ventilation.\n\nThe FDA has set emission standards for new microwave ovens at a power density of 5 milliwatts per square centimeter at a distance of 5 centimeters from any point on the outer surface of the oven. Typical new ovens have a leakage of only 0.2 mW/cm2 at that distance—a tenth of the FDA standard. Dirt, mechanical abuse and everyday wear and tear can eventually reduce the effectiveness of the door seals, thus increasing leakage. If you're concerned about emissions from an older oven, you can purchase leakage sensors at many hardware and home improvement stores or online. Keeping the seals on the oven and door clean, as well as opening and closing the door gently, will help keep your oven safe to use. So go ahead and ogle your latest culinary masterpiece while it cooks. Your food will cook, but your head will not. Or so one certainly hopes. \n\n**************************************************************
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Commercially:\n=============\nFractional distillation of liquified air. This method involves:\n\n1. Liquifying air which is mostly Oxygen and Nitrogen\n2. Heating liquid air.\n3. Cooling at different temperatures to collect different gases.\n\nOne of the major bi-products of this method is Nitrogen. \n\nLaboratory:\n===========\nHeating some oxide in presence of a catalyst or electrolysis.
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calculate the heating and cooling loads.Calculate the air flow rate knowing inlet and exit temperatures.From the air flow rate size the duct such that the air speed does not exceed 6ft/minute. Look up the temperatures in the comfort zone on your air psychometric chart. Knowing the pressure drop choose your grills such that you lose just enough of the pressure not to influence the flow rate or the comfort air speed mentioned above. Return air plus make up air should be constant approximately. Good luck!
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1. Get a common heavy pliers.\n\n2. Get a common three- or four-tined eating fork.\n\n3. Use the pliers to bend the inner tine(2) back at the base to a 90-degree angle, so that only the outer two tines are facing out.\n\n4. Fill a Dutch oven withabout three inches of water.\n\n5. Wet a standard bath towel.\n\n6. Proceed to the nearest operational electrical outlet providing at least 10 amps of 120 volt, single-phase alternating current.\n\n7. Place the wet towel on the floor near the outlet.\n\n8. Place the water-filled Dutch oven on top of the towel.\n\n9. Remove your shoes and stand in the Dutch oven, ensuring your feet are covered with water. \n\n10. Insert the fork in the outlet, making contact with the home wiring.\n\n11. Die, and spare the world another person so dumb, he asks on Yahoo! Answers how to violate the Yahoo! Terms of Service and invade other Yahoo! users' privacy.