Q.

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           [2024]

1 1.59A  
2 13.33 A  
3 1.33 A  
4 15.1 A  

Ans.

(2)       

             Efficiency η=80%,Pi=4kW=4000W

              VP=10V, VS=240V

              For primary coil: IP=PiVP=400010=400A

              η=VSISVPIP80100=240IS10×400

             IS=13.33A