Question

Which of the following methods can be used to charge a metal sphere positively without touching it? Select the most appropriate.

Options

• Connect the positive terminal of a battery and float the other end of the battery.

• Rub it with a piece of silk.

• Rub it with a piece of fur.

• Bring a negatively charged rod near the sphere and touch it to ground for a short while.

Answer 1

Bring a negatively charged rod near the sphere and touch it to ground for a short while.

Explanation:

This can be accomplished through induction; if a negative charge rod is placed near the sphere (at a distance that is not in contact), it attracts positive charge inside the sphere to one side and collects negative charges on the other; when the sphere's surface is connected to the earth, the negative charge goes to the earth and the sphere remains positively charged.