Resistivity, thermistors and superconductivity Quiz
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5 questions, one answer each
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1. A wire has resistance 8.0 Ω. A wire of the same material and diameter has twice the length. What is its resistance?
- A. 4.0 Ω
- B. 8.0 Ω
- C. 16 Ω
- D. 32 Ω
2. A copper wire has length 2.0 m and area 1.0 × 10⁻⁶ m². The resistivity of copper is 1.7 × 10⁻⁸ Ω m. What is the resistance?
- A. 0.034 Ω
- B. 3.4 Ω
- C. 8.5 × 10⁻¹⁵ Ω
- D. 0.34 Ω
3. What happens to the resistance of an ntc thermistor when its temperature rises?
- A. It increases because the lattice ions vibrate more
- B. It decreases because more charge carriers are released
- C. It stays constant
- D. It becomes zero at a critical temperature
4. Which of the following is an application of superconductors?
- A. Producing very strong magnetic fields with large currents
- B. Making filament lamps
- C. Measuring temperature at room temperature
- D. Making diodes
5. In Required practical 5 a graph of R against L is plotted for a wire of area 3.0 × 10⁻⁸ m². The gradient is 16 Ω m⁻¹. What is the resistivity?
- A. 1.9 × 10⁹ Ω m
- B. 4.8 × 10⁻⁷ Ω m
- C. 2.1 × 10⁻⁹ Ω m
- D. 5.3 × 10⁻⁷ Ω m