The increased resistance of a wire if its length is doubled and original cross sectional area is halved will be: (Given R = original resistance of wire)
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 4R
Resistance of a wire is,
$R=ρ\frac{l}{A}$
$l$ = length of wire
A = Cross-section area
when $l'=2l$ and $A'=A/2$
$R'=ρ\frac{2l}{A/2}=4ρ\frac{l}{A}$=4R$