The efficiency of a transformer is very high because

Explain the use of a transformer for the distribution of power over long distances.

The core of a transformer is made up of:

The quantity that remains unchanged in the output with respect to the input in an ideal transformer is . . . . . . .

$A$ current of $5 \,A$ is flowing at $220 \,V$ in the primary coil of a transformer. If the voltage produced in the secondary coil is $2200 \,V$ and $50 \%$ of power is lost, then the current in the secondary will be (in $A$)

$A$ 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 $\%$)