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Question
A potentiometer wire has resistance of per unit length of 0.1 Ω/m. A cell of e.m.f. 1.5 V balances against a 300 cm length of the wire. Find the current in the potentiometer wire.
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Solution
Given:
σ = 0.1 Ω/m,
E = 1.5 V,
L = 300 cm = 3 m.
To find:
Current through potentiometer (I) = ?
Formulae:
- σ = R/L
- I = E/R
Calculation:
From formula (1),
R = σL
= 0.1 × 3
= 0.3 Ω
From formula (2),
I = 1.5/0.3
= 5 A
Current through the potentiometer wire is 5 A.
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