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

In a primary coil,a $5\,A$ current is flowing at $220\,V$. In the secondary coil,a voltage of $2200\,V$ is produced. The ratio of the number of turns in the secondary coil to the primary coil is:

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

Which of the following statements is correct regarding a step-down transformer?

The instrument which works on the principle of mutual inductance is

The output voltage of a transformer connected to a $220 \, V$ line is $1100 \, V$ at a $1 \, A$ current. Its efficiency is $100 \%$. The current coming from the line is ........ $A$.