A wire of resistance 4 ohm is stretched to twice its original length. The resistance of stretched wire would be
Options
(a) 4Ω
(b) 8Ω
(c) 16Ω
(d) 2Ω
Correct Answer:
16Ω
Explanation:
Resistance R = ρℓ / A
ℓ’ = 2 ℓ ⇒ A’ = A / 2
R’ = ρ [2 ℓ / (A / 2)] = 4R = 4 × 4Ω = 16Ω