Question

a piece of wire of resistance 20 ohm is drawn out so that its length is increased to twice its length calculate the resistance of the wire the new situation​

Answer 1

Answer:

When length of wire is doubled i.e. 2l

Also it's area of cross section becomes half i.e

2

A

Resistance R=

A

ρl

=20Ω

New Resistance ,

R

′

=

A

′

ρl

′

=

A

ρ(2l)×2

=4

A

ρl

=4(

A

ρl

)

=4×20

=80Ω