Question

A current of $I$ ampere is flowing through a resistor $R$ ohm. The rate of heat generated in joules will be :

• A. $I^2R$
• B. 4.2$I^2R$
• C. $\frac{I^2R}{4.2}$
• D. given by none of the above expressions

Answer 1

Answer: (B)

Heat produced $Q = I^2 \, Rt = \frac{V^2}{R} t = VIt$
When R is doubled , keeping V constant Q is halved
When V is doubled, Q becomes 4 times, because resistance was not changed
As $Q = l^2Rt$ in joule, so the rate of production of heat is $\frac{Q}{t} I^2 \, R$