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JAMB Physics 2000 Question 28

Question 28

Electrostatics

An electron of charge 1.6 × 10−19 C and mass 9.1 × 10−31 kg is accelerated between two metal plates with velocity of 4 × 107 m s−1, the potential difference between the plates is

  1. A.4.55 × 101 V
  2. B.9.10 × 101 V
  3. C.4.55 × 102 V
  4. D.4.55 × 103 V
Show the answer and explanation

Answer: D (4.55 × 103 V)

Explanation

eV = ½mv2, so V = 9.1 × 10−31 × (4 × 107)2 ÷ (2 × 1.6 × 10−19) = 4.55 × 103 V.