Question

A copper wire with diameter of 0.5 mm and resistivityof 1.6 if diameter is doubled

Answer 1

Answer:

Given, diameter, d=0.5 mm

resistivity, ρ=1.6×10

−8

Ωm

Resistance, R=10 Ω

Let the length of wire be l.

A=πd

2/4

R=ρl/A

= πd 2 /4ρl

​

⟹l= 4ρRπd 2

l= 4×1.6×10 −8

10×3.14×(0.5×10 −3) 2

l=122 m

R∝1/d 2

If the diameter is doubled, resistance will be one-fourth.

Hence, new resistance =2.5Ω