Question

A current of $I$ ampere is flowing through a resistance of $Rohm$, the rate of heat generated in calories will be

• A. $I^{2}R$
• B. $4.2I^{2}R$
• C. $\frac{I^{2}R}{4.2}$
• D. None of these

Answer 1

The correct option is C

$\frac{I^{2}R}{4.2}$

1. The heat generated by a current $I$ flowing through a resistance $R$ is given by: $H=I^{2}Rt$

2. Rate of heat generated by a current $I$ flowing through a resistance $R$ is given by: $\frac{H}{t}=I^{2}R$ $joule/sec$

Now, $1cal=4.2joules$

$\therefore 1joule=\frac{1}{4.2}cal$

3. Therefore, the rate of heat generated $=\frac{I^{2}R}{4.2}$$cal/sec$

Hence, option (C) is the correct answer.