Question

When the switch is open in lowermost loop (secondary circuit) of a potentiometer the balance point length is 60 cm. When the switch is closed with a known resistance of R = 4 ohm, the balance point length decreases to 40 cm. Find the internal resistance of the unknown battery?
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Answer 1

Answer:

When the switch is open in lowerpoint loop of a potentiometer, the balance point length is 60cm. When the switch is closed with a known resistance of R=4Ω the balance point length decreases to 40cm

Explanation:

Answer 2

Answer:

The internal resistance is 2ohm.

Explanation:

R = 4ohm

L = 60cm

X = 40cm

Here,

The internal resistance is denoted by r.

The resistance of the wire is denoted by R.

The balance point length when the circuit is open is denoted by L.

The balance point length when the circuit is close is denoted by X.

Now,

By the equation,

$r=R(\frac{L}{X} -1)\\r=4(\frac{60}{40} -1)\\r = 2ohm$

So, the internal resistance is 2ohm.