A lamp rated at 60 W, 120 V is to be operated from a 240 V, 50 Hz domestic supply
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Circuits · Electric Circuits
Problem
A lamp rated at 60 W, 120 V is to be operated from a 240 V, 50 Hz domestic supply. To ensure correct operation, a series resistor is inserted with the lamp.
(i) Calculate the resistance of the lamp when it glows at its rated voltage.
(ii) Determine the value of the series resistor required so that the lamp operates at its rated power when connected across the 240 V supply.
(iii) Calculate the power dissipated in the series resistor under these conditions and comment briefly on the efficiency of using a series resistor for this purpose.