Question

Calculate the new resistance of a conductor having resistance 4 ohm when it is streched so that it's diameter to half as before.​

Answer 1

Answer:

Let length and cross-section area of the wire be  l and A respectively.

∴  Resistance     R=ρAl         where  ρ is the resistivity of the material

Given :      R=4 Ω

For    l′=2l  and  A′=2A, resistance of the wire be  R′

∴   R′=ρA′l′=ρA/22l=4ρAl=4R

∴    R′=4×4 Ω=16 Ω