The resistances in the two arms of the meter bridge are 5Ω and RΩ, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6, the resistance R is
15Ω
Case - 1
5R=ℓ1100−ℓ1 .....(1)
Case-2
When R is shunted with an equal resistance R, shunt placed parallel to R.
5R2=1.6ℓ1100−1.6ℓ1.....(2)
By (1) and (2)
2[100−1.6ℓ1]=1.6[100−ℓ1]200−3.2ℓ1=160−1.6ℓ140=1.6ℓ1ℓ1=25 cmℓ1=25 cm
Put this in (1)
5R=2575R=15Ω