A metal sphere is placed on an insulating stand. A negatively charged rod is brought close to it. If

JAMB Physics 2023 318 views
Source: JAMB · 2023

A metal sphere is placed on an insulating stand. A negatively charged rod is brought close to it. If the sphere is earthed and the rod is taken away, what will be the charge on the sphere?

  1. The sphere will have a net negative charge.
  2. The sphere will have a net positive charge. ✓
  3. The sphere will remain neutral.
  4. The sphere will become polarized
Explanation

The negative rod pushes electrons in the sphere away. Earthing lets those electrons flow into the ground.

The sphere now has fewer electrons than protons. When the rod is taken away, it keeps a net positive charge. This is charging by induction.

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