Question

An electric iron is based upon the principle of
(A) Heating effect of current
(B) Magnetic effect of current
(C) Chemical effect of current
(D) None of these

Answer 1

Hint:An electric iron is an instrument used to press the clothes and make it neat. This works with the use of the electrical power supply. Here, the electrical energy from the power supply gets converted into thermal heat energy.

Complete step by step solution:
The electric iron consists of the metal that conducts the electric current. Mainly the iron is used. Since they conduct the current fast and convert it into thermal energy. This electric iron works on the principle of the heating effect of electric current. The metal gets heated when the current flows on it. This is because, when the electric current flows through the metal surface, all the electrons present in the metal energize and get vibrated.

This continuous vibration of the particles creates heat. This heat is used to press the clothes and make it heat. This heat mainly depends upon the input current, resistance of the metal surface to the flow of the current and the time taken for the heating up of the metal. The Joules heating effect of electric current is given by considering $P$ as the power, $V$ is the potential difference, $I$ is the current flowing through it, $R$ is the resistance developed in the metal and $T$ is the time taken for the heating is
$P=VI=I^{2}RT$

Thus the option (A) is correct.

Note:In the electric iron, there will be a bimetallic strip. It is a metal attached to the iron in which both possess different expansion coefficient to the heat. So when the iron gets overheated, the bimetallic strip bends due to overheating, this causes the circuit to open. This prevents the firing.