A coil has a resistance of 10 Ω at 0 °C. Its temperature coefficient of resistance is 4.0 × 10⁻³ K⁻¹. What is its resistance at 50 °C?
Correct answer D. 12 Ω
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Current Electricity MCQs
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Why does the resistance of a metal conductor increase when its temperature rises?
Correct answer D. Lattice ions vibrate with larger amplitude, so free electrons collide more often
What is the sign of the temperature coefficient of resistance of a pure semiconductor such as silicon?
Correct answer C. Negative
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The resistivity of a metal wire depends on which of the following?
Correct answer D. The material and its temperature
A wire 2.0 m long with cross-sectional area 0.50 mm² has a resistance of 2.2 Ω. What is the resistivity of its material?
Correct answer A. 5.5 × 10⁻⁷ Ω m
A uniform wire of resistance R is stretched so that its length doubles while its volume stays the same. What is its new resistance?
Correct answer B. 4R
Which of the following is a non-ohmic device?
Correct answer C. A semiconductor diode
A wire carries a steady current of 3.2 mA. Take e = 1.6 × 10⁻¹⁹ C. How many electrons pass a given cross-section of the wire each second?
Correct answer A. 2.0 × 10¹⁶
A steady current of 0.50 A flows through a lamp for 2.0 minutes. How much charge passes through the lamp?
Correct answer C. 60 C
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What is the SI unit of resistivity?
Correct answer D. Ω m