An electron is released from rest in a uniform electric field of 5 × 10⁴ N/C. Its speed after traveling 0.01 m is:
Correct answer: A. 4.2 × 10⁶ m/s
- A. 4.2 × 10⁶ m/s
- B. 8.4 × 10⁶ m/s
- C. 2.1 × 10⁶ m/s
- D. 5.9 × 10⁶ m/s
Explanation
Using energy conservation, work done by the field equals kinetic energy gained: qEΔx = (1/2)mv². For an electron (q = 1.6 × 10⁻¹⁹ C, m = 9.1 × 10⁻³¹ kg), E = 5 × 10⁴ N/C, Δx = 0.01 m, v = √(2qEΔx/m) ≈ 4.2 × 10⁶ m/s.
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Electrostatics describes forces between charges through Coulomb's law, electric fields and field intensity, then uses electric potential to measure energy per unit charge. Capacitors store charge and electrical energy, with capacitance depending on geometry and dielectric material, not simply on the amount of charge present.
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