Question

In the electric network shown in the figure, use Kirchhoff's rules to calculate the power consumed by the resistance R = 4 $\Omega$.

Answer 1

Using Kirchhoff's law in the lower loop,

$\sum V=0or,E_2-(I_1+I_2)R=0giving,I_1+I_2=\frac{E_2}{R}=\frac{6}{4}=1.5A$

Thus current through the resistance $R$ is $1.5$ Amperes. Hence Power consumed by it will be :

$P=I^{2}R={(I_1+I_2)}^2\times 4=1.5^2\times 4=9Joules$