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

In a step-down transformer,the number of turns in:

$A$ transformer is used to light a $100 \,W-110 \,V$ lamp from a $220 \,V$ mains. If the main current is $0.5 \,A$, the efficiency of the transformer is: (in $\%$)

$A$ transformer consists of $500$ turns in the primary coil and $10$ turns in the secondary coil with a load of $10\, \Omega$. Find the current in the primary coil when the voltage across the secondary coil is $50\, V$. (in $A$)

$A$ loss-free transformer has $500$ turns on its primary winding and $2500$ turns in its secondary winding. The meters of the secondary indicate $200 \, V$ at $8 \, A$ under these conditions. The voltage and current in the primary are:

Write important uses of transformer.