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.
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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
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 = ....(i)
= (E + I.r) = I.R
Putting value of I from (i) in above equation we get
= . R
R + r = . R
r = - R
Here = V
r = .R
r = (-1).R
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