Question

The turn ratio of a transformer is given as $2:3$. If the current through the primary coil is $3A$. What is the current through the secondary coil?

• A. 1 A
• B. 4.5 A
• C. 2 A
• D. 1. 5 A

Answer 1

The correct option is C 2 A

Given: Turn ratio (n) = 2 : 3

Let, current through primary coil be $I_p$
Current through secondary coil be $I_s$
Number of turns in primary coil be $N_p$
Number of turns in secondary coil be $N_s$
Voltage across the primary coil be $V_p$
Voltage across the secondary coil be $V_s$

The turn ratio of a transformer (n) = $N_s:N_p$ = $2:3$

We know that in a transformer $\frac{N_s}{N_p}=\frac{V_s}{V_p}$ ......(i)

Also, in an ideal transformer, there is no loss of energy, so power in primary coil is equal to power in secondary coil.
$\Rightarrow$ $V_p\times I_p$ = $V_s\times I_s$
$\Rightarrow$ $\frac{V_s}{V_p}=\frac{I_p}{I_s}$ ......(ii)

From (i) and (ii), we get,
$\frac{N_s}{N_p}=\frac{I_p}{I_s}$
$\Rightarrow$ $I_s=I_p\times \frac{N_p}{N_s}$

$\Rightarrow$ $I_s=3\times \frac{2}{3}$
$\Rightarrow$ $I_s=2A$