Question

The current in a circuit is doubled, keeping other parameters constant. The heat generated in the circuit will be _________ of its initial value.

• A. $2times$
• B. $4times$
• C. $3times$
• D. $8times$

Answer 1

The correct option is B

$4times$

According to joule's law of heating:
Heat generated, $H=I^{2}Rt$
when current $I$ flows through the resistance $R$ for time $t$
Now the current is doubled.
So current flowing through the same resistance becomes $2I$.
Now, heat generated $H^{\prime }={\left(2I\right)}^{2}Rt$
$H^{\prime }=4{\left(I\right)}^{2}Rt$
$H^{\prime }=4H$
Hence, heat generated will be four times of its initial value.