JAMB Physics 2023 Paper

Concept:A transformer relates the primary and secondary voltages to the number of turns on each coil.For an ideal transformer, $\frac{V_p}{V_s} = \frac{N_p}{N_s}$.Explanation:Identify the given values: primary voltage $V_p = 2.2\,\text{kV} = 2200\,\text{V}$.Secondary voltage $V_s = 110\,\text{V}$.Secondary turns $N_s = 25$ turns.Let $N_p$ be the primary turns.Substitute into the transformer equation:$$\frac{2200}{110} = \frac{N_p}{25}$$Simplify the left side: $2200 \div 110 = 20$.So, $20 = \frac{N_p}{25}$.Multiply both sides by 25:$$N_p = 20 \times 25 = 500$$Answer:The primary winding has $500$ turns.Therefore, the correct option is D. 500.