A resistor of resistance is first connected across a d.c
PHYSICS · Multi-part · CBSE · Physics · Alternating Current · Alternating Current
Problem
A resistor of resistance 60Ω is first connected across a 200V d.c. supply and then across a 200V r.m.s. a.c. supply of the same frequency.
(i) Calculate the power dissipated in the resistor in each case.
(ii) The resistor is required to dissipate a total of 7.2×105J of energy. Determine the time taken to do so for each supply.
(iii) Show that the ratio of the two times obtained equals the ratio of the squares of the effective voltages applied, and explain physically why this must be so.