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A wire of length l and resistance R is stretched to get the radius of croos -section halved . what is the new resistance of the wire after streching ? |
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Answer» Answer: Answer Correct option is A 16R Let length & cross sectional AREA of wire be ℓ & a respectively. ρ be the specific resistance, then R=ρ a ℓ
If radius BECOMES half, area becomes 4 1
th or cross sectional area after the stretch = 4 a
. Let its length increases to ℓ ′ . Since volume remains the same in the process, ℓa=ℓ ′ × 4 a
⇒ℓ ′ =4ℓ Let R' be the resistance of stretched wire, R ′ =ρ a/4 4ℓ
=16×ρ a ℓ
=16R Explanation: PLEASE mark as brianllest and thanks and follow please friends |
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