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Question
A potentiometer wire has a length of 1.5 m and a resistance of 10 Ω. It is connected in series with the cell of emf 4 Volt and internal resistance 5 Ω. Calculate the potential drop per centimeter of the wire.
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Solution
Given: L = 1.5 m, R = 10 Ω, E = 4 V, r = 5 Ω.
K = `"ER"/(("R + r")"L")`
∴ K = `(4 xx 10)/((10 + 5)1.5)`
`= 40/(15 xx 15/10)`
`= 400/225 "V"/"m" = 400/22500 "V"/"cm" = 0.0178 "V"/"cm"`
The potential drop per centimetre of the wire is `0.0178 "V"/"cm"`
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