The primary and secondary voltage of an ideal step-down transformer is $200 \,V$ and $25 \,V$ respectively. The secondary is connected to a device,which draws a current of $2 \,A$. The current in the primary is (in $\,mA$)

$A$ common transistor radio set requires $12\,V$ $(D.C.)$ for its operation. The $D.C.$ source is constructed by using a transformer and a rectifier circuit,which are operated at $220\,V$ $(A.C.)$ on standard domestic $A.C.$ supply. If the number of turns in the secondary coil is $24$,then the number of turns in the primary coil is:

$A$ step-down transformer has a $N_{S}$ to $N_{P}$ ratio of $1: 20$. If $8 \, V$ are developed across a $0.4 \, \Omega$ secondary load, the primary current will be: (in $ \, A$)

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

Large transformers,when used for some time,become hot and are cooled by circulating oil. The heating of a transformer is due to: