What useful power does a 60 W lamp, designed for a rated voltage of 220 V, consume if a voltage

What useful power does a 60 W lamp, designed for a rated voltage of 220 V, consume if a voltage of 120 V is applied to it?

Given:

W = 60 watts – the power of the electric lamp;

U1 = 220 Volts – the voltage for which the electric lamp is designed;

U2 = 120 Volts – the voltage that was applied to the lamp.

It is required to determine W1 (Watt) – the useful power of the lamp at a voltage equal to U2.

Let’s find the strength of the electric current consumed by the lamp:

I = W / U1 = 60/220 = 6/22 = 0.27 Amperes (the result has been rounded up to one hundredth).

Then the useful power will be equal to:

W1 = I * U2 = 0.27 * 120 = 32.4 watts.

Answer: at a voltage of 120 volts, the lamp will consume power equal to 32.4 watts.