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Saturday, 31 October

JEE Main 2024 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 1 February 2024, Shift 2, Physics Q49

Question 49 of 90 in this shift, Physics question 19 of 30, Section A.

To measure the temperature coefficient of resistivity α\alpha of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25∘25^\circC and resistance of the semiconductor arm is 3 mΩ\Omega. Arm BC is cooled at a constant rate of 2∘2^\circC/s. If the galvanometer G shows no deflection after 10 s, then α\alpha is :

The figure, in words

Wheatstone-bridge type circuit with junctions A, B, C, D: arm AB = 0.8 m-ohm, arm AD = 1 m-ohm, arm DC = 3 m-ohm, arm BC drawn as a plain thick line (the semiconductor); galvanometer G between B and D; battery V = 5 mV connected across A and C.
  1. (1)−1×10−2 ∘C−1-1\times10^{-2}\,^\circ\mathrm{C^{-1}}Official answer
  2. (2)−1.5×10−2 ∘C−1-1.5\times10^{-2}\,^\circ\mathrm{C^{-1}}
  3. (3)−2×10−2 ∘C−1-2\times10^{-2}\,^\circ\mathrm{C^{-1}}
  4. (4)−2.5×10−2 ∘C−1-2.5\times10^{-2}\,^\circ\mathrm{C^{-1}}

Official answer

Option 1

NTA final key.

Chapter
Current Electricity
Topic
Ohm's Law and Resistance
Idea tested
Temperature Dependence in Semiconductors

Same idea in other shifts

Asked 2× in all
  1. 6 Apr 2023, Shift 1 · Q41The resistivity (ρ\rho) of semiconductor varies with temperature. Which of the following curve represents the correct behaviourEasyDiagram basedHas a figure

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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.