$A$ power transmission line feeds input power at $2300\,V$ to a step-down transformer with its primary windings having $4000$ turns,giving the output power at $230\,V.$ If the current in the primary of the transformer is $5\,A,$ and its efficiency is $90\%,$ the output current would be......$A$

In a transformer,the mutual inductance between the primary and secondary coils is $0.5 \ H$. The resistances of the primary and secondary coils are $20 \ \Omega$ and $5 \ \Omega$ respectively. To induce a current of $0.4 \ A$ in the secondary coil,what is the required rate of change of current in the primary coil in $A/s$?

The coils of a step-down transformer have $500$ and $5000$ turns. In the primary coil, an $AC$ current of $4 \,A$ at $2200 \,V$ is sent. The value of the current and potential difference in the secondary coil is:

$A$ transformer may be used to provide maximum power transfer between two $AC$ circuits that have different impedances $Z_1$ and $Z_2$. The ratio of turns $N_1/N_2$ needed to meet this condition is given by :-

Write important uses of transformer.

In a transformer,the number of turns in the primary coil is $140$ and that in the secondary coil is $280$. If the current in the primary coil is $4 \ A$,then the current in the secondary coil is (in $A$):