AP EAMCET Engineering 22 Apr 2019 Shift 1 Paper

Consider the diagram of the system as shown below.The emf of the cell that gives balancing length

l

3

is calculated as,
E=K(

l

3

)
E=

V

l

(

l

3

)
E=

V

3

.....(I)
When the length of potentiometer increases by

l

2

, the new length is calculated as,
l1=l+

l

2

l1=

3l

2

The new potential gradient is,
K′=V(

3l

2

)
K′=

2V

3l

The emf is calculated as,
E=K′l′

V

3

=

2V

3l

l′
l′=

l

2