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A cooktop (American English), stovetop (American English) or hob (British English), is a device commonly used for
cooking Cooking, cookery, or culinary arts is the art, science and craft of using heat to prepare food for consumption. Cooking techniques and ingredients vary widely, from grilling food over an open fire to using electric stoves, to baking in vario ...
that is commonly found in kitchens and used to apply heat to the base of pans or pots. Cooktops are often found integrated with an
oven upA double oven A ceramic oven An oven is a tool which is used to expose materials to a hot environment. Ovens contain a hollow chamber and provide a means of heating the chamber in a controlled way. In use since antiquity, they have been us ...
into a
kitchen stove A kitchen stove, often called simply a stove or a cooker, is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of direct heat for the cooking process and may also contain an oven, used for bak ...
but may also be standalone devices. Cooktops are commonly powered by gas or electricity, though oil or other fuels are sometimes used.


Gas

Gas cooktops consist of one or more gas burners with arrangements to control the rate of flow. They often have integral lighters or (in older models)
pilot light Merker Tankless water heating, tankless gas-fired water heater from the 1930s, with pilot light clearly visible through the aperture in the front cover. The large opening allowed for the manual lighting of the pilot light by a lit match or taper ...
s, and may have safety interlocks designed to reduce the risk of hazardous gas leaks. Gas cooking has been associated with negative health effects, such as reduced pulmonary function and a higher rate of respiratory symptoms in children.


Electric


Coil

Electric coil cooktops use electric heating elements that directly heat pots placed on them. They are inexpensive to buy and maintain, but are considered more difficult to clean than smooth-top models.


Ceramic

A ceramic hob consists of a low-expansion thermal glass-ceramic that is transparent to infrared. This surface houses radiant or
halogen The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this grou ...
heaters below it. The advantage of this arrangement is that the heat can be quickly controlled.


Induction

Induction cooking involves the electrical heating of a cooking vessel by magnetic induction instead of by radiation or
thermal conduction Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as its ''thermal conductivity'', and is denoted . Heat spontaneously flows along a tem ...
from an electrical
heating element A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is independ ...
or from a flame. Because inductive heating directly heats the vessel, very rapid increases in temperature can be achieved and changes in heat settings are fast, similar to gas. Paper presented at the 2014 ACEEE Summer Study on Energy Efficiency in Buildings In an induction cooktop ("induction hob" or "induction stove"), a coil of copper wire is placed under the cooking pot, and an alternating electric current is passed through it. The resulting oscillating
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
induces a magnetic flux that repeatedly magnetises the pot, treating it like the lossy
magnetic core A magnetic core is a piece of magnetic material with a high magnetic permeability used to confine and guide magnetic fields in electrical, electromechanical and magnetic devices such as electromagnets, transformers, electric motors, generators, ...
of a
transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's ...
. This produces large
eddy current Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction or by the relative motion of a conductor in a magne ...
s in the pot, which, because of the resistance of the pot, heat it. For nearly all models of induction cooktops, a cooking vessel must be made of, or contain, a
ferromagnetic Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...
metal such as
cast iron Cast iron is a class of iron–carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impuriti ...
or some stainless steels. However,
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish- ...
, glass, non-magnetic stainless steels, and aluminum vessels can be used if placed on a ferromagnetic disk that functions as a conventional hotplate. Induction cooking is quite efficient, which means it puts less
waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ( ...
into the kitchen, can be quickly turned off, and has safety advantages compared to gas stoves. Cooktops are also usually easy to clean, because the cooktop itself does not get very hot. However, they must be regularly maintained to prevent dirt buildup and possible damage. If the induction coil is of lesser diameter than the cooking pot, and the pot has low thermal conductivity, use of high power can potentially warp the pot due to non-uniform heating. 6" coils are common in low-end portable units, which is smaller than most pots and pans.


Ventilation and exhaust

Cooktops often have a kitchen hood installed overhead to expel or filter smoke, fumes and undesirable odors that result from cooking. However, when installation of an updraft ventilation system is undesirable or impossible (for example in an open kitchen design), a cooktop with an integrated ''downdraft'' ventilation system can be used instead. Such systems draw cooking fumes downwards rather than upwards, eliminating the need of an overhead installation. They are however less effective than overhead systems, and may not be able to extract fumes emanating from taller pots.


Placement


Installed

Cooktops are virtually ubiquitous in kitchens. They may be built into a stove along with an oven. Alternatively, cooktops are often installed independently in work surfaces.


Hot plate

A hot plate is a portable self-contained tabletop
small appliance A small domestic appliance, also known as a small electric appliance or minor appliance or simply a small appliance, small domestic or small electric, is a portable or semi-portable machine, generally used on table-tops, counter-tops or ot ...
cooktop that features one, two or more electric
heating element A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is independ ...
s or gas burners. A hot plate can be used as a standalone appliance, but is often used as a substitute for one of the burners from an
oven upA double oven A ceramic oven An oven is a tool which is used to expose materials to a hot environment. Ovens contain a hollow chamber and provide a means of heating the chamber in a controlled way. In use since antiquity, they have been us ...
range or a
kitchen stove A kitchen stove, often called simply a stove or a cooker, is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of direct heat for the cooking process and may also contain an oven, used for bak ...
. Hot plates are often used for food preparation, generally in locations where a full kitchen stove would not be convenient or practical. A hot plate can have a flat or round surface. Hot plates can be used for traveling or in areas without electricity.


References

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