Question

In the adjoining circuit, the battery E₁ has as emf of 12 volt and zero internal resistance, while the battery E has an emf of 2 volt. If the galvanometer reads zero, then the value of resistance X ohm is

• A. 10
• B. 100
• C. 500
• D. 200

Answer 1

Answer: (B)

100

Answer 2

For zero deflection in galvanometer the potential different across X should be E = 2V

In this condition $\frac{12X}{500 + X} = 2$

∴ X = 100 Ω