Q: A step up transformer operates on a 230 V line and a load current of 2 ampere. The ratio of the primary and secondary winding is 1 : 25. What is the current in the primary ?

Sol: using the relation ,

$\large \frac{N_s}{N_p} = \frac{I_s}{I_p} $

$\large I_s = \frac{N_s}{N_p} \times I_p $

$\large I_s = \frac{25}{1} \times 2 $

= 50 A