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. $4\Omega$
• B. $2\Omega$
• C. $3\Omega$
• D. The emf of the cell is required

Answer 1

The correct option is B $2\Omega$

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