JEE Main 2021 — Current Electricity Question with Solution
From: JEE Main 2021 (Online) 26th February Evening Shift
Question
A wire of 1 has a length of 1 m. It is stretched till its length increases by 25%. The percentage change in resistance to the nearest integer is :
Choose an option
Show full solutionCorrect option: D
Correct answer
D56%
Step-by-step explanation
R0 = 1
R1 = ?
l0 = 1m
l1 = 1.25 m
A0 = A
As volume of wire remains constant so
A0l0 = A1l1 A1 =
Now
Resistance (R) =
So % change in resistance
R1 = ?
l0 = 1m
l1 = 1.25 m
A0 = A
As volume of wire remains constant so
A0l0 = A1l1 A1 =
Now
Resistance (R) =
So % change in resistance
Practice this on the real CBT interface
Solve this JEE Main question (and the rest of the Current Electricity chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.
Solve interactively →About this question
This is a previous-year question from JEE Main 2021, covering the Current Electricity 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.