$A$ 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 output power in a step-up transformer used in practice is . . . . . .

In a step-up transformer,the voltage in the primary is $220\,V$ and the current is $5\,A$. The secondary voltage is found to be $22000\,V$. The current in the secondary (neglect losses) is......$A$.

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 $\,mA$)

$A$ small town with a demand of $800 \; kW$ of electric power at $220 \; V$ is situated $15 \; km$ away from an electric plant generating power at $440 \; V$. The resistance of the two-wire line carrying power is $0.5 \; \Omega/km$. The town gets power from the line through a $4000-220 \; V$ step-down transformer at a sub-station in the town.
$(a)$ Estimate the line power loss in the form of heat.
$(b)$ How much power must the plant supply,assuming there is negligible power loss due to leakage?
$(c)$ Characterise the step-up transformer at the plant.

$A$ step-up transformer has a turns ratio of $10:1$. $A$ cell of $e.m.f. = 5 \, V$ is connected to the primary coil. What is the secondary voltage developed?