Question

a piece of wire is resistance 20 ohm is drawn out so that it's length is increased twice it's original length calculate the resistance of wirein new situation

Answer 1

Answer:80

Explanation:

Suppose the length of R1 = 20Ω resistance wire is I, its area of cross-section is,4 and its resistivity is ρ Then,

R= ρl/A =20

When length becomes twice (2l), then its area of cross-section will become half (A/2).

R2= ρ.2L/ (A/2)= 4(ρl/A) = 4*20 = 80