In a step-up transformer, the turn ratio is $1 : 2$. A Leclanche cell $(e.m.f. = 1.5 \, V)$ is connected across the primary. The voltage developed in the secondary would be ......... $V$.

$A$ step-down transformer transforms $220 \text{ V}$ to $11 \text{ V}$. If the currents in the primary and secondary coils are $5 \text{ A}$ and $90 \text{ A}$ respectively,the efficiency of the transformer is: (in $\%$)

Which of the following is correct for a real transformer?

In a transformer,the number of turns in the primary coil and secondary coil are $5$ and $4$ respectively. If $240 \ V$ is applied to the primary coil,then the ratio of the current in the primary coil to the secondary coil is:

$A$ 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 $A$)

The primary winding of a transformer has $100$ turns and its secondary winding has $200$ turns. The primary is connected to an ac supply of $120 \,V$ and the current flowing in it is $10 \,A$. The voltage and the current in the secondary are