JEE Main 2022 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 30 June 2022, Shift 1, Physics Q45

Question 45 of 90 in this shift, Physics question 15 of 30, Section A.

An electric cable of copper has just one wire of radius 9 mm. Its resistance is 14

\Omega

. If this single copper wire of the cable is replaced by seven identical well insulated copper wires each of radius 3 mm connected in parallel, then the new resistance of the combination will be :

(1)9 $\Omega$
(2)18 $\Omega$ Official answer
(3)28 $\Omega$
(4)126 $\Omega$

Official answer

Option 2

NTA final key.

Chapter: Current Electricity
Topic: Ohm's Law and Resistance
Idea tested: Resistivity and Geometry

Same idea in other shifts

Asked 10× in all

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.