For no deflection(balanced condition) 10.8=3R
⇒R=2.4mΩ
Temperature fall in 10s=20∘C
ΔR=RαΔt
⇒α=RΔtΔR=3×202.4−3
=-1\times {10}^{-2}^{\circ}{C}^{-1}
JEE Main 2024 — Physics Electromagnetism
2024mcqmedium
To measure the temperature coefficient of resistivity α 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∘C and resistance of the semiconductor arm is 3mΩ. Arm BC is cooled at a constant rate of 2∘Cs−1. If the galvanometer G shows no deflection after 10s, then α is:
Official previous-year question
Held on 1 Feb 2024 · Verified 6 Jul 2026.
Options
- A
−2×10−2C−1∘
- B
−1.5×10−2C−1∘
- C
−1×10−2C−1∘
- D
−2.5×10−2C−1∘
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