Question

An ideal transformer has $500$ primary turns and $10$ secondary turns. The primary coil carries current $2A$ and its voltage is $11,000V$. Current and voltage in the secondary coil will be

• A. $100A,220V$
• B. $0.04A,220V$
• C. $100A,550000V$
• D. $0.04A,550000V$

Answer 1

The correct option is C $100A,550000V$


From the above circuit of a transformer, applying KVL

$E_1+N_1(-\frac{d\varphi }{dt})=0$ (primary coil)
$E_2=N_2(-\frac{d\varphi }{dt})=i_{2}R$ (secondary coil)

$\Rightarrow \left|\frac{E_1}{E_2}\right|=\left|\frac{N_1}{N_2}\right|$

where $N_1$ and $N_2$ are no of turns in primary and secondary coil.

i.e $\frac{11,000}{E_2}=\frac{500}{10}$
$\Rightarrow E_2=\frac{11,000}{50}=220V$

For calculating currents, $\frac{I_2}{I_1}=\frac{N_1}{N_2}$
$\Rightarrow \frac{I_2}{2}=\frac{500}{10}$
$\Rightarrow I_2=100A$