Question

explain the working of an electric iron. On what factors does the heat produced by it depend?

Answer 1

Answer:

Irons are rather simple in how they work. They work like an electric heater. They have a heating element made out of a metal alloy that gets hot when electricity is applied. Wired in series with the heating element is a thermostat. The thermostat is made of two electrical contacts that are designed to bend away from each other as the iron gets hot. The knob turns a screw which control how hard the contacts must bend to separate and break the electrical connection. The higher the thermostat is turned, the hotter the iron must get before the electrical contacts separate. Then when the iron starts to cool, the contacts make connection again, thus keeping the iron steadily at the desired temperature.Basically you apply a voltage to a load (the iron's heating element) which induces a current. The current through the load generates heat according to the formula Power = Current^2 * Resistance.

The heat produced in conducting wire is given by joules law as,

H=I² Rt

i ) The amount of heat produced in current conducting wire, is proportional to the square of the amount of current that is flowing through the circuit, when the electrical resistance of the wire and the time of current flow is constant.

 i.e H∝I²    (when R, t are constant)

II) Heat generated due to the flow of current  is proportional to the time of current flow, when the electrical resistance and amount of current flow is constant.

  ie H∝t (when I,R are constant)

III) The amount of heat produced is proportional to the electrical resistance of the wire when the current in the circuit and the time of current  flow is constant.

  ie H∝R (when I, t are constant)

Explanation: