Question

two wires of the same material and same length have radii 1 mm and 2 mm respectively compare first the resistances, the specific resistance

Answer 1

Hope this'll help you....

Answer 2

Given : Two wires of the same material and same length have radii 1mm and 2mm respectively.

To find : ratio of their resistances and their specific resistances.

solution : we know, R = ρL/A

where ρ is specific resistance of material.

as A = πr²

so, R = ρL/πr²

here material and length of wires are same so, R ∝ 1/r².

i.e., R₁/R₂ = (r₂/r₁)² = (2mm/1mm)² = 4 : 1

Therefore the ratio of their resistances is 4 : 1

as two wires are made of the same material, so specific resistances of both wires are same.

Therefore the ratio of their specific resistances is 1 : 1