Question

A potentiometer wire has length L. While calculating EMF of cell null point comes at L/4. If the area of cross section of potentiometer wire is doubled, then find the new null point.​

Answer 1

ANSWER = 1/2

Explanation:

Let x be the desired length.

Potential gradient in the first case = E0/  l  

 E=(  3/ l )⋅(E0/1 )=E0/3                         (1)

Potential gradient in the second case.

=  Eo  /3l/2    = 2E0/ 3l

∴E=(x)     2E 0/3l                               (2)

From equations (i) and (ii), we get  

E0/3    =(2E0/ 3l)x

 ⇒x= 1/2  

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