Question

A transformer has $500$ primary turns and $10$ secondary turns. If the secondary has resistive load of $15 \,\Omega$, the currents in the primary and secondary respectively, are

• A. $0.16 A, 3.2 \times 10^{-3} A$
• B. $3.2 \times 10^{-3} A , 0.16 A$
• C. $0.16 A, 0.16 A$
• D. $3.2 \times 10^{-3} A , 3.2 \times 10^{-3} A$

Answer 1

Answer: (B)

As $\frac{N_s}{N_p} = \frac{I_p}{I_s} \Rightarrow \frac{10}{500} = \frac{I_p}{I_s}$
or $\frac{I_p}{I_s} = \frac{1}{50}$ or $I_s = 50 I_p$
This condition is satisfied only when current in primary is $3.2 \times 10^{-3}$ A and in secondary 0.16 A.