$A$ step-down transformer is used on a $1000\,V$ line to deliver $20\,A$ at $120\,V$ at the secondary coil. If the efficiency of the transformer is $80\%$,the current drawn from the line is ......$A$.

In a step-up transformer, the turn ratio is $1:10$. A resistance of $200 \, \Omega$ connected across the secondary is drawing a current of $0.5 \, A$. What is the primary voltage and current?

Primary side of a transformer is connected to $230 \ V, 50 \ Hz$ supply. The turns ratio of primary to secondary winding is $10:1$. The load resistance connected to the secondary side is $46 \ \Omega$. The power consumed in it is: (in $W$)

$A$ transformer consists of $500$ turns in the primary coil and $10$ turns in the secondary coil with a load of $10\, \Omega$. Find the current in the primary coil when the voltage across the secondary coil is $50\, V$. (in $A$)

$A$ transformer with efficiency $80\%$ works at $4\, kW$ and $100\, V$. If the secondary voltage is $200\, V$, then the primary and secondary currents are respectively:

Why is a soft iron core used in a transformer?