HSC Science (General) 12th Board ExamMaharashtra State Board
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# A Potentiometer Wire Has a Length of 4 m and a Resistance of 5Ω . What Resistance Should Be Connected in Series with a Potentiometer Wire and a Cell of E.M.F. 2 V Having Internal Resistance 1 ω to Get a Potential Gradient of 10-3 V/cm - HSC Science (General) 12th Board Exam - Physics

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#### Question

A potentiometer wire has a length of 4 m and a resistance of 5 Ω. What resistance should be connected in series with a potentiometer wire and a cell of e.m.f. 2 V having internal resistance 1 Ω to get a potential gradient of 10-3 V/cm ?

#### Solution

Given:

L = 4m

R = 5Ω

E = 2V

Internal resistance of cell,

r = 1Ω

K = 10-3 V/cm

K = 10-3 /10-2

K = 0.1 V/m

To find:

RE = ?

Formulae:

K = IR/L

I = E/(R + r + RE)

Solution:

Since,

I = E/(R + r + RE)

∴ K = IR/L

K = ER/(R + r + RE)L

0.1 = (2 × 5)/(5 + 1 + RE) × 4

0.1 × 4 × (6 + RE) = 10

6 + RE = 25

∴ RE = 19Ω

Is there an error in this question or solution?

#### APPEARS IN

2013-2014 (October) (with solutions)
Question 8.1 | 7.00 marks

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Solution A Potentiometer Wire Has a Length of 4 m and a Resistance of 5Ω . What Resistance Should Be Connected in Series with a Potentiometer Wire and a Cell of E.M.F. 2 V Having Internal Resistance 1 ω to Get a Potential Gradient of 10-3 V/cm Concept: Metre Bridge.
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