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JAMB Physics 1994 Question 41

Question 41

Electrostatics

When a biro pen rubbed on a dry silk cloth is moved very close to a piece of paper on a dry table, the pen is found to pick up the paper. This is because

  1. A.both the pen and the cloth are magnetized
  2. B.the pen is magnetized but the cloth is not
  3. C.the pen is charged while the cloth is magnetized
  4. D.both the pen and the cloth are charged.
Show the answer and explanation

Answer: D (both the pen and the cloth are charged.)

Explanation

Rubbing transfers electrons, so the pen and the cloth gain equal and opposite charges; the charged pen attracts the light paper.