Question

In a metere bridge, the balance length from left end
(standard resistance of 1 N is in the right gap) is found
to be 20cm the length of Resistance in left a gap
m and radius is 2mm its specific resistance is​

Answer 1

For meter bridge: 

QP=100−ll  where P= unknown resistance , Q= known resistance, l= balancing length.

Thus, P=100−ll×Q=100−2020×1=41=0.25Ω