Question

In the combination of resistances shown in the figure the potential difference between B and D is zero, when unknown resistance (x) is

• A. 4 Ω
• B. 2 Ω
• C. 3 Ω
• D. The emf of the cell is require

Answer 1

Answer: (B)

2 Ω

Answer 2

The potential difference across B, D will be zero, when the circuit will act as a balanced wheatstone bridge and $\frac{P}{Q} = \frac{R}{S} \Rightarrow \frac{12 + 4}{x} = \frac{1 + 3}{1/2}$ ⇒ x = 2Ω