JEE Main 2021 · PhysicsMultiple choiceSingle correctEasyCalculation

JEE Main 17 March 2021, Shift 1, Physics Q11

Question 11 of 90 in this shift, Physics question 11 of 30, Section A.

Two identical metal wires of thermal conductivities

K_1

and

K_2

respectively are connected in series. The effective thermal conductivity of the combination is :

(1) $\frac{K_1K_2}{K_1+K_2}$
(2) $\frac{2K_1K_2}{K_1+K_2}$ Official answer
(3) $\frac{K_1+K_2}{2K_1K_2}$
(4) $\frac{K_1+K_2}{K_1K_2}$

Official answer

Option 2

NTA final key.

Chapter: Thermal Properties of Matter
Topic: Heat Conduction
Idea tested: Equivalent Thermal Conductivity in Series

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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.