Question

Two wires of the same material and same length have radii r1 and r2 respectively.Compare

1. Their resistance

2. Their specific resistance

Answer 1

1.
Let R1andR2 be the resistances of the wires.

Then R1=r×ρlπr21 ...(i)

and R2=r×ρlπr22 ...(i)

From Eqs. (i) and (ii), we get :



R1R2=ρlπr21ρlπr21=r22r21




Therefore R1:R2=r22Lr21


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2.

As they are made up of the same material, their specific resistances are the same.