Physics, asked by melvinlty3268, 11 months ago

A resistance r is connected across a cell of emf e and internal resistance r. A potentiometer now measures the potential difference between the terminals of the cell as v. Write the expression for r in terms of e, v and r.

Answers

Answered by raunakyadav3003
16

Answer:

e=I(R+r)  

V=IR

∴e/V=R+V/R

=1+r/R

=r/R

=(e/v−1)

∴r=R(e/V−1)

Explanation:

Answered by fistshelter
11

A potentiometer is three terminal resistor with sliding contact that forms an adjustable voltage divider. it act as rheostat or variable resistor.

Let internal resistance be r and R be resistance connected in series with potentiometer and voltage applied be v.

Let I be the current flowing through the main circuit in the given figure

Since R and r are in series

then I = \frac{E}{R+r}     ....(i)

V_{AB} = (E + I.r) = I.R

Putting value of I from (i) in above equation we get

V_{AB}  =  \frac{E}{R+r} . R

R + r = \frac{E}{V_{AB} }. R

r = \frac{E.R}{V_{AB} } - R

Here V_{AB} = V

r = \frac{E-V}{V}.R

r = (\frac{E}{V}-1).R

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