Question

Figure below shows a balanced Wheatstone's network. If it is disturbed by changing $P$ to $22 \,\Omega$, then which of the following steps will bring the bridge again in balanced state?

• A. By increasing $S$ by $3 \,\Omega$
• B. By increasing $Q$ by $20 \,\Omega$
• C. By increasing $R$ by $30\, \Omega$
• D. Both (a) and (b)

Answer 1

Answer: (D)

At balanced condition,
$\frac{P}{Q}=\frac{S}{R} \Rightarrow \frac{22}{200}=\frac{30}{300}$
So, it can be balanced again by increasing the resistance $S$ by $3 \,\Omega$ or by increasing $Q$ by $20\, \Omega$.