Question

A $4\Omega$ and a $2\Omega$ coil are connected in parallel. What is their combined resistance ? A total current of 3 A passes through the coils. What current passes through the $2\Omega$ coil?

Answer 1

The coils of the resistors of 4 Ω and 2 Ω are connected in parallel.

$\therefore \frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}\frac{1}{R}=\frac{1}{4}+\frac{1}{2}\frac{1}{R}=\frac{3}{4}R=\frac{4}{3}\Omega$
Combined resistance of the 4 Ω coil and the 2 Ω coil = 1.33 Ω

Total current = 3 A
The voltage across the whole cicuit,as in case of parallel circuit volatge is same scross all resistances.
$V=IR$
$V=3\times \frac{4}{3}=4V$
Therefore, the current through the 2 Ω coil,
$I=\frac{V}{R}I=\frac{4}{2}AI=2A$