Question

An auto transformer having 1250 turns is connected across a 250 V ac supply. What secondary voltage will be obtained if a tap is taken at 900${}^{th}$ turn.

• A. 70 V
• B. 180 V
• C. 892.85 V
• D. 347.2 V

Answer 1

The correct option is B 180 V

$V_1=250N_1=1250,N_2=900$

Secondary voltage $=V_2=V_1\times \frac{N_2}{N_1}$

$=250\times \frac{900}{1250}=180V$