Electric charge

What is electric charge?

This refers to the physical property of matter that causes it to experience a force when placed in an electromagnetic field

What causes two charges to repel?

This occurs when they have the same electrostatic forces.

What causes two charges to attract?

This occurs when they hace different electrostatic forces

What are the methods of charging?

• Charging by friction

• Charging by induction

• Charging contact/conduct

What is charging by friction?

This is the process by which two different insulating materials are rubbed and electrons get transferred from one body to another

What are examples of charging by friction?

1. When a plastic rod is rubbed with a piece of cloth and electrons are transferred from the rod to the cloth and as a result the rod becomes positively charged and the cloth becomes negatively charged.

2. When a Ballon is rubbed against your hair and the Ballon becomes charged with static electricity.

What is charging by induction?

This is the method of transferring electrical energy from one object to another without them coming in direct contact with each other.

What are examples of charging by induction?

1. Wirelessly charging a smartphone on a charging pad

2. Photocopy machines use this principle to transfer toner onto paper. The toner, which carries an electric charge is attracted to the areas of the paper that were selectively charged by the photoconductive drum.

What is charging by contact/conduction?

This is where charge between objects are directly transferred upon physical contact, resulting in both objects acquiring charges of equal magnitude

What are examples of charging by conduction/contact?

1. When you touch a metal object such as a doorknob after walking across a carpet, the electrons are transferred from your body to the object which causes a sudden discharge of static electricity.

2. if you have one piece of tape on top of another then rip them apart, electrons from one piece of tape are transferred to the other, making one tape negatively charged and the other positively charged.

What is an electric field?

This Is the region surrounding an electrically charged body in which a force is exerted on other electric charge.

Describe one hazard of static electricity

How does a cloud become charged?

This is caused due to the friction between layers of air and water molecules rising and falling within it.

How is lightning formed?

This occurs when the negative charge on the base of the cloud repels the electrons further into the ground which results in a net positive charge accumulating at the surface of the earth.

What are some useful applications of static electricity?

Electrostatic spraying

Dust precipitators

Lightning conductors