Question

(a) What is meant by heating effect of electric current ? Give two applications of heating effect of current.
(b) State the law relating heat dissipated in an electric circuit with the current, potential difference and time.
(c) 50 J of heat is produced each second in a $2\Omega$ resistor. Find the potential difference across the resistor.

Answer 1

(a) When the conductor offers resistance to the flow of current, the work done by the electric current in overcoming this resistance is converted into heat energy. This is called heating effect of current.
Application of heat energy :
(i) This effect is used in electric fuse wire for protecting household wiring.
(ii) It is also used in electric iron, water heaters etc.

(b) Joule's law of heating states that the heat produced in a wire is directly proportional to the square of the current, resistance of wire and time for which the current is passed.
$H\propto i^{2}RT$


(c) Given, amount of heat produced, $H=50J$, resistance, $R=2\Omega$ and time taken, $T=1s$
We know, $P=\frac{V^2}{R}$ and $P=\frac{H}{T}$
$\therefore$ $\frac{H}{T}=\frac{V^2}{R}$
$\Rightarrow$ $V^2=\frac{H}{T}\times R$
$=\frac{50}{1}\times 2=100volts$
$\Rightarrow$ $V=\sqrt{100}=10volts$