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JEE Main 2023 — Mathematics in Physics Question with Solution

JEE Main 2023 (06 Apr Shift 1)

Question

The length of a metallic wire is increased by 20% and its area of cross-section is reduced by 4%. The percentage change in resistance of the metallic wire is ________.

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Show full solutionCorrect answer: 25
Correct answer
25

Step-by-step explanation

The given data is 

l'=1.2lA'=0.96A

Using the formula R=ρlA, the new resistance is 

R'=1.2ρl0.96A

⇒R'=1.25R

⇒ΔR=1.25R-R=0.25R

Hence, the percentage increase is 

=ΔRR×100=0.25RR×100=25%

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About this question

This is a previous-year question from JEE Main 2023, covering the Mathematics in Physics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.