Question

Nichrome wire of length L and radius 'R' has resistance of 10Ω. How would the resistance of the wire change when:

(i) Only length of the wire is doubled ?

(ii) Only diameter of the wire is doubled ? Justify your answer.

Answer 1

(i) R ∝ L

So resistance becomes two times i.e., R = 20 Ω

(ii) R ∝ 1/A ∝ 1/d²  

So when the diameter is doubled, resistance becomes one-fourth of the original i.e., R =2.5 Ω