$A$ step-up transformer operates on $220 \,V$ and supplies a current of $2 \,A$. The ratio of primary and secondary windings is $1:20$. The current in the primary is (in $\,A$)

$A$ transformer with $80 \%$ efficiency works at $4 \text{ kW}$ and $100 \text{ V}$. If the secondary voltage is $240 \text{ V}$, then the primary current is . . . . . . . (in $A$)

$A$ step-down transformer connected to an $AC$ mains supply of $220 \, V$ is made to operate a $11 \, V, 44 \, W$ lamp. Ignoring power losses in the transformer,what is the current in the primary circuit? (In $A$)

What is a transformer? Write its principle and describe its construction.

$A$ 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$)

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