Q.

The total length of potentiometer wire AB is 50 cm in the arrangement as shown in figure. If P is the point where the galvanometer shows zero reading then the length AP is _______ cm.  [2026]

1 30  
2 20  
3 25  
4 15  

Ans.

(1)

6RAP=4RPB;

ℓAP+ℓPB=50    ...(i)

RAPRPB=ℓAPℓPB=32

ℓAP=35×50=30 cm