Question

The ratio of lengths of two wires made up of same material is 2 : 3 and the ratio of areas of cross section 3 : 2 . The ratio of their resistances is

Answer 1

Resistance is directly proportional to the length of this wire and inversely proportional to the area of cross section or area.

i.e.

R = L/A

where l is length of wire and a is area of cross section.

Now,

A/q

R1 = 2/3 & R2= 3/2

So, R1/R2 = 2/3 ÷ 3/2 = 4/9

Hence, the ratio of resistance required is 4/9.