Electrical Charges and Charging by Friction Quiz

5 Questions

When a glass rod is rubbed with a piece of silk cloth, what happens to the rod and the cloth?

The rod becomes positively charged while the cloth has a negative charge.

Which of the following cannot be charged easily by friction?

An inflated balloon

Write T against true and F against false in the following statement: Like charges attract each other (T/F)

Write T against true and F against false in the following statement: A charged glass rod attracts a charged plastic straw (T/F)

Explain why a charged body loses its charge if we touch it with our hand.

When we touch a charged body with our hand, the excess charge is transferred to the ground, equalizing the charge and causing the body to lose its charge.

Study Notes

Charging by Friction

When a glass rod is rubbed with a piece of silk cloth, the rod becomes positively charged and the cloth becomes negatively charged.
This is because electrons are transferred from the glass rod to the silk cloth, leaving the rod with a positive charge and the cloth with a negative charge.

Charging by Friction: Exceptions

Metals cannot be charged easily by friction because they are good conductors of electricity and electrons are free to move freely.

Electric Charges

Like charges repel each other (opposite charges attract each other).
A charged glass rod repels a charged plastic straw if they have the same charge (both positive or both negative).

Discharging

A charged body loses its charge when we touch it with our hand because the electrons are transferred to or from the body to the ground through our body, which acts as a conductor.
This is because the human body is a good conductor of electricity and provides a path for the electrons to flow to or from the ground, neutralizing the charge.