Concepts Of Physics MCQ Edition [Volume 2]

Exam: Concepts Of Physics MCQ Edition [Volume 2]
Subject: Physics
Chapter: Electric Current in Conductors

Concepts Of Physics MCQ Edition [Volume 2] · Physics · Electric Current in Conductors

In the figure, the potentiometer wire AB is 40 cm long. Where must...

In the figure, the potentiometer wire

AB

40 \text{ cm}

long. Where must the free end of the galvanometer be connected on

AB

for the galvanometer to show zero deflection?
In the figure, the potentiometer wire AB is 40 cm long. Where must the free end of the galvanometer be connected on AB

In the figure, the potentiometer wire AB is 40 cm long. Where must the free end of the galvanometer be connected on AB

Options

A $24 \text{ cm}$ from $A$
B $20 \text{ cm}$ from $A$
C $16 \text{ cm}$ from $A$
D $32 \text{ cm}$ from $A$

Correct answer

C. $16 \text{ cm}$ from $A$

Step-by-step solution

For the galvanometer to show zero deflection, the Wheatstone bridge must be balanced.

Let the balancing length from point

A

l

. Since the total length of the wire is

40 \text{ cm}

, the remaining length is

(40 - l)

.

Using the balanced Wheatstone bridge principle:

\dfrac{8}{12} = \dfrac{l}{40 - l}

\dfrac{2}{3} = \dfrac{l}{40 - l}

3l = 80 - 2l

5l = 80

l = 16 \text{ cm}

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