Q.

A resistance wire connected in the left gap of a metre bridge balances a 10 Ω resistance in the right gap at a point which divides the bridge wire in the ratio 3 : 2. If the length of the resistance wire is 1.5 m, then the length of 1 Ω of the resistance wire is                [2020]
 

1 1.0×10-2m  
2 1.0×10-1m  
3 1.5×10-1m  
4 1.5×10-2m  

Ans.

(2)

Unknown is X,R=10Ω.

Here, l1l2=32  ;  XR=l1l2

X=32×10X=15Ω

Thus, 1.5 m length has resistance 15Ω hence, length of 1Ω of the resistance wire =1.515=0.1m=1.0×10-1m