Nichrome wire of length l and radius r has resistance of 10 `Omega` . 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 .

Explanation

(i) `R prop L`
So resistance becomes two times i.e R `=20 Omega`
(ii) `R prop (1)/(A) prop (1)/(d^(2))`
So when diameter is doubled resistance becomes one fourth of the original i.e., R = 2.5 `Omega`