JAMB Physics 2010 Paper

Concept:For resistors connected in parallel, the reciprocal of the total resistance is the sum of the reciprocals of the individual resistances.Explanation:For three $4\ \Omega$ resistors in parallel, the equivalent resistance $R$ is:$$\frac{1}{R} = \frac{1}{4} + \frac{1}{4} + \frac{1}{4} = \frac{3}{4}$$Therefore:$$R = \frac{4}{3}\ \Omega$$The applied potential difference is $V = 16\ \mathrm{V}$.Using Ohm's law, $I = \frac{V}{R}$:$$I = \frac{16}{\frac{4}{3}} = 16 \times \frac{3}{4} = 12\ \mathrm{A}$$So the total current flowing in the circuit is $12\ \mathrm{A}$.Answer:The total current in the circuit is $12\ \mathrm{A}$, which corresponds to option B.