An unknown resistance R1 is connected in series with a resistance of 10 Ω. This combinations is connected to one gap of a metre bridge while a resistance R2 is connected in the other gap. The balance point is at 50 cm. Now, when the 10 Ω resistance is removed the balance point shifts to 40 cm. The value of R1 is (in ohm)
For first balancing condition
⇒ . For second balancing condition
⇒ ⇒