The output power in a step-up transformer used in practice is . . . . . .

$A$ transformer has $100$ turns in the primary coil and carries $8 \, A$ current. If the input power is $1 \, kW$, the number of turns required in the secondary coil to have $500 \, V$ output is:

The instrument which works on the principle of mutual inductance is

$A$ step-down transformer is used on a $1000\,V$ line to deliver $20\,A$ at $120\,V$ at the secondary coil. If the efficiency of the transformer is $80\%$,the current drawn from the line is ......$A$.

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.

$A$ step-down transformer transforms $220 \text{ V}$ to $11 \text{ V}$. If the currents in the primary and secondary coils are $5 \text{ A}$ and $90 \text{ A}$ respectively,the efficiency of the transformer is: (in $\%$)