QJEEM22Ph7bc7: JEE Main 2022 Physics - Class 12 JEEM22Ph7bc7 Solution: Eight copper wire of length l and diameter d are joined in…

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QJEEM22Ph7bc7: JEE Main 2022 Physics - Class 12 JEEM22Ph7bc7 Solution: Eight copper wire of length l and diameter d are joined in…

Eight copper wire of length $l$ and diameter $d$ are joined in parallel to form a single composite conductor of resistance $R$ . If a single copper wire of length $2 l$ have the same resistance $(R)$ then its diameter will be ____________ d.

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Accepted Answer

JEE Main 2022 (Online) 25th July Morning Shift Physics - Current Electricity Question 128 English Explanation

$R A B = R$

$R = \frac{1}{8}$ (Resistance of one wire)

$= \frac{1}{8} ρ \frac{l}{π \frac{d^{2}}{4}} = \frac{ρ l}{2 π d^{2}}$

Resistance of copper wire of length $2 l$ and diameter $x = R$

$ρ \frac{2 l}{π \frac{x^{2}}{4}} = R$

$\frac{8 ρ l}{π x^{2}} = \frac{ρ l}{2 π d^{2}}$

$16 d^{2} = x^{2}$

$x = 4 d$

QJEEM22Ph7bc7: JEE Main 2022 Physics - Class 12 JEEM22Ph7bc7 Solution: Eight copper wire of length l and diameter d are joined in…

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