Question

The current through a 60 W lamp rated for 250 V is

• A. 0.24 A
• B. 4.2 A
• C. 0.5 A
• D. 6 A

Answer 1

The correct option is A 0.24 A

The electric power in watts associated with a complete electric circuit or a circuit component represents the rate at which energy is converted from the electrical energy of the moving charges to some other form, e.g., heat, mechanical energy, or energy stored in electric fields or magnetic fields. The power is given by the product of applied voltage and the electric current. That is, $P=VI$.

For a 60 W lamp rated for 250 V, the current through is given as $I=\frac{P}{V}=\frac{60}{250}=0.24A$.

Hence, the current flowing through the lamp is 0.24 A.

Substituting I=V/R in the above formula, we get, $P=\frac{V^2}{R}$.

Given that the voltage is 250 V and the power is 60 W, the resistance of the

bulb is calculated as follows.

$R=\frac{V^2}{P}=\frac{{250}^2}{60}=1041.67\Omega$.

When the voltage drops to 200 V, the power is calculated as follows.

$P=\frac{V^2}{R}=\frac{{200}^2}{1041.67}=38.40W$

Hence, the power of the bulb is reduced to 38.40 W.