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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 3 m Ω . Arm BC is cooled at a constant rate of 2°C/s. If the galvanometer G shows no deflection after 10 s, then α is : 0.8m Ω 1m Ω 3m Ω C V = 5mV G A B D

1. –1 × 10 –2 °C –1
2. –2.5 × 10 –2 °C –1
3. –1.5 × 10 –2 °C –1
4. –2 × 10 –2 °C –1

Correct answer: –1 × 10 –2 °C –1

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