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

Q: 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 $S\,?$ ............... $\Omega$

a Let $X$ be the equivalent resistance between $S$ and $6\, \Omega$. $\therefore \quad \frac{1}{X}=\frac{1}{S}+\frac{1}{6}$ .......$(i)$ Therefore, the equivalent circuit diagram drawn below. For a balanced Wheatstone bridge, we get $\frac{P}{Q}=\frac{R}{X} \quad \text { or } \quad \frac{2}{2}=\frac{2}{X} \quad \Rightarrow \quad X=2 \,\Omega$ From eqn. $(i)$, we get $\frac{1}{2}=\frac{1}{S}+\frac{1}{6} \quad$ or, $\quad \frac{1}{S}=\frac{2}{6} \quad$ or, $\quad S=3\, \Omega$

SECTION - A [PHYSICS - MCQ]

GSEB - English Medium

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 $S\,?$ ............... $\Omega$

A$3$
B$6$
C$1$
D$2$

AIPMT 2007, Medium

STD 11 Science
NEET
STD 12 - 3. current electricity
Physics

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