Question

For a transformer, the turns ratio is $3$ and its efficiency is $0.75$. The current flowing in the primary coil is $2\,A$ and the voltage applied to it is $100\, V$. Then the voltage and the current flowing in the secondary coil are _________ respectively.

• A. 150 V, 1.5 A
• B. 300 V, 0.5 A
• C. 300 V, 1.5 A
• D. 150 V, 0.5 A

Answer 1

Answer: (B)

Given, $\frac{n_{s}}{n_{p}}=3 ; \,\,\, \eta=0.75 ; l_{p}=2 A$ and $V_{p}=100\, V$
We know that,
$\eta=\frac{V_{S}}{V_{P}} \frac{l_{S}}{l_{P}}$
Or $\eta=\left(\frac{n_{S}}{n_{P}}\right) \frac{l_{s}}{l_{P}} \,\,\,\,\,\,\left(\because \frac{n_{s}}{n_{p}}=\frac{V_{s}}{V_{D}}\right)$
$\Rightarrow 0.75=\frac{3 \times l_{s}}{2}$
$\Rightarrow l_{s}=0.5\, A$
By the relation, $\frac{n_{s}}{n_{P}}=\frac{V_{s}}{V_{P}}$
$\Rightarrow 3=\frac{V_{s}}{100} $
$\Rightarrow V_{s}=300\, V$