The primary winding of a transformer has $500$ turns,whereas its secondary has $5000$ turns. The primary is connected to an $ac$ supply of $20\, V$,$50\, Hz$. The secondary will have an output of

$A$ transformer is used to light a $100\,W$ and $110\,V$ lamp from a $220\,V$ main. If the main current is $0.5\,A$, the efficiency of the transformer is approximately .....$\%$

The instrument which works on the principle of mutual inductance is

$A$ step-down transformer is connected to a main supply of $200\,V$ to operate a $6\,V$,$30\,W$ bulb. The current in the primary coil is.....$A$

$A$ step-up transformer operates on a $230\, V$ line and supplies a load of $2\, A$. The ratio of the primary and secondary windings is $1 : 25$. The current in the primary is.... (in $, A$)

$A$ power transmission line feeds input power at $2300\,V$ to a step-down transformer with its primary windings having $4000$ turns,giving the output power at $230\,V.$ If the current in the primary of the transformer is $5\,A,$ and its efficiency is $90\%,$ the output current would be......$A$