Question

In figure. the galvanometer shows no deflection. What is the resistance X?

• A. $7\Omega$
• B. $14\Omega$
• C. $21\Omega$
• D. $28\Omega$

Answer 1

Answer: (D)

$28\Omega$

In the given figure, the galvanometer shows no deflection. The set of four resistors forms a Wheatstone bridge. So, this means that there is no potential and hence the ratio of arms must be equal such that

$\frac{10}{40}=\frac{7}{X}$

$X=28\Omega$