Current Electricity: Internal Resistance by Potentiometer MCQ

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Internal Resistance by PotentiometerHardQuestion 31632

Question

A cell balances at 120 cm on a potentiometer wire. When an external 10 Ω resistor is connected, balance shifts to 100 cm. Internal resistance of cell is:

A
2 Ω
Correct
B
10 Ω
C
1 Ω
D
0.5 Ω

Correct answer

2 Ω

Explanation

r = R(l₁−l₂)/l₂ = 10×(120−100)/100 = 10×20/100 = 2 Ω.

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