Question

Three resistances $P, Q, R$ each of $2\, \Omega$ and an unknown resistance $S$ form the four arms of a Wheatstone bridge circuit. When a resistance of $6\, \Omega$ is connected in parallel to $S$ the bridge gets balanced. What is the value of $S$ ?

• A. $3\, \Omega$
• B. $6\, \Omega$
• C. $1\, \Omega$
• D. $2\, \Omega$

Answer 1

Answer: (A)

$3\, \Omega$

Answer 2

for balanced wheatstone bridge circuit
$\frac{2}{2}=\frac{2}{\left(\frac{6 S }{ S +6}\right)}$
$\Rightarrow S +6=3 S$
$\Rightarrow S =3 \Omega$