Question

In an electrical circuit two resistors of 2 $\Omega$ and 4 $\Omega$ respectively are connected in series to a 6 V battery. The heat dissipated by the 4 $\Omega$ resistor in 5 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 $20\text{J}$

Equivalent resistance for resistors connected in series, $\text{R}={\text{R}}_1+{\text{R}}_2=2+4=6\Omega$
Voltage, $V=6V$
Current, $I=\frac{V}{R}=\frac{6}{6}=1A$
Current flowing through the resistors are same.
Heat dissipated by the 4 $\Omega$ resistor in 5 s is given by,
$Heat=I^{2}Rt=(1{)}^2\times 4\times 5=20J$