WAEC Physics 2017 Paper

Concept:Combine series and parallel resistances, then apply Ohm's law to find the current.Explanation:The two $1\,\Omega$ resistors are connected in parallel.For parallel resistance: $\frac{1}{R_p} = \frac{1}{1} + \frac{1}{1} = 2$.So, $R_p = 0.5\,\Omega$.This parallel combination is in series with another $1\,\Omega$ resistor.Total resistance: $R_{\text{total}} = 1\,\Omega + 0.5\,\Omega = 1.5\,\Omega$.Using Ohm's law, $V = IR$.Given $V = 3\,\mathrm{V}$, we have $3 = I \times 1.5$.Therefore, $I = \frac{3}{1.5} = 2\,\mathrm{A}$.Answer:The ammeter reading will be $2\,\mathrm{A}$, which is option C.