The transformation ratio in a step-up transformer is

$A$ 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 $40,000-220 \; V$ 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.
(Neglect,as before,leakage losses). Hence,explain why high-voltage transmission is preferred?

$A$ step-down transformer has a turns ratio of $20:1$. If $8 \, V$ is applied across a $0.4 \, \Omega$ secondary coil, then the primary current will be: (in $ \, A$)

$A$ 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 $\%$)

$A$ transformer has an efficiency of $80 \%$ and works at $10 \ V$ and $4 \ kW$. If the secondary voltage is $240 \ V$, then the current in the secondary coil is: (in $A$)

Due to which reasons do energy losses occur in an actual transformer?