JEE Main 2021PhysicsCurrent ElectricityEasyMCQ

JEE Main 2021 — Current Electricity Question with Solution

JEE Main 2021 (22 Jul Shift 1)

Question

A Copper (Cu) rod of length 25 cm and cross-sectional area 3 mm2 is joined with a similar Aluminium (Al) rod as shown in figure. Find the resistance of the combination between the ends A and B.

(Take resistivity of Copper =1.7×10-8 Ωm, Resistivity of aluminium =2.6×10-8 Ωm)

Choose an option

Show full solutionCorrect option: D
Correct answer
D0.858 mΩ

Step-by-step explanation

R=R1R2R1+R2=ℓA·ρ1ρ2ρ1+ρ2
R=25×10-23×10-6×1.7×2.6×10-164.3×10-8
R=0.858 mΩ

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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.