Resistivity and conduction Quiz
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5 questions, one answer each
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1. A wire has resistance 6.0 Ω. A wire of the same material and length but half the diameter has resistance:
- A. 3.0 Ω
- B. 12 Ω
- C. 24 Ω
- D. 1.5 Ω
2. In I = nqvA for a copper wire, why is v so small?
- A. The charge q is very small
- B. The number of electrons per unit volume n is very large
- C. The area A is very large
- D. The current is always very small
3. A graph of R against l for a uniform wire has gradient 15 Ω m⁻¹ and the wire has area 8.0 × 10⁻⁸ m². What is its resistivity?
- A. 1.2 × 10⁻⁶ Ω m
- B. 5.3 × 10⁸ Ω m
- C. 1.9 × 10⁻⁷ Ω m
- D. 1.2 × 10⁻⁷ Ω m
4. Which statement explains why glass has a much higher resistivity than copper?
- A. Glass has a much smaller cross-sectional area
- B. Glass has almost no free charge carriers
- C. Glass electrons have a larger charge
- D. Glass is always at a lower temperature
5. The current in a wire is tripled with n, q and A unchanged. The drift velocity:
- A. is unchanged
- B. is multiplied by 9
- C. is divided by 3
- D. is multiplied by 3