Question

In an electrical circuit, two resistors of $2\Omega$ and $4\Omega$ respectively are connected in series to a $6\text{V}$ battery. The heat dissipated by the 4 $\Omega$ resistor in $5\text{s}$ will be:

• A. $5\text{J}$
• B. $10\text{J}$
• C. $20\text{J}$
• D. $30\text{J}$

Answer 1

The correct option is C $20\text{J}$

The equivalent resistance for resistors connected in series, ${\text{R}}_{\text{e}q}={\text{R}}_1+{\text{R}}_2=2+4=6\Omega$

Voltage, $\text{V}=6\text{V}$
Current, $\text{I}=\frac{\text{V}}{\text{R}}=\frac{6}{6}=1\text{A}$

The electric current flowing through the resistors is the same.
The heat dissipated by the $4\Omega$ resistor in $5\text{s}$ is given by,
$={\text{I}}^2\text{Rt}=(1{)}^2\times 4\times 5=20\text{J}$