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Current Electricity: Free Electron Density MCQ

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Free Electron DensityHardQuestion 31617

Question

Copper has atomic mass 64, density 8960 kg/m³, 1 free electron per atom. Free electron density n is approximately:
  1. A
    8.5×10²⁸ m⁻³
    Correct
  2. B
    8.5×10²⁵ m⁻³
  3. C
    6×10²³ m⁻³
  4. D
    1×10³⁰ m⁻³

Correct answer

8.5×10²⁸ m⁻³

Explanation

n = N_A × density / (atomic mass in kg) = 6×10²³ × 8960/0.064 ≈ 8.5×10²⁸ m⁻³.

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