Question

Two wires A and B are formed from the same material and same mass. Diameter of B is twice of A. If the resistance of wire A is 32 ohm.. find the resistance of wire B!

Answer 1

a and b are two wires.

We know, R =ρ l/A

Given, Da =Db/2 = ra=rb/2 (r is radius of wire)

so, Aa = Ab/4

Ab = 4Aa

and lb =la/4

Now, Rb =ρ lb/Ab

Rb =ρ (la/4) / 4Aa

= ρ la/Aa(1/16)

Given, (Ra =32Ω = ρ la/Aa )

So, Rb = 32/16 = 2 Ω