UPSEE 2017 Solved Paper

Given,
two cylindrical rods A and B have same resistivities and same length.
We know that,
R=

ρl

A

=

ρI

πr2

A
Resistance of rod A,RA=

ρl

π(2R)2

.....(i)
B
Resistance of rod‌B,RB=

ρ1

π(R)2

......(ii)
Dividing Eq. (i) by Eq. (ii), we get

RA

RB

=

ρ1

π(2R)2

×

π(R)2

ρl

RA

RB

=

1

4

RAI

RBI

=

1

4

⇒

VA

VB

=

1

4