JAMB - Physics (1994 - No. 32)
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
both the pen and the cloth are magnetized
the pen is magnetized but the cloth is not
the pen is charged while the cloth is magnetized
both the pen and the cloth are charged
คำอธิบาย
They are all charged either positively or negatively