8.01 Electric charge (1)

Question 1

What is electrostatic charge?

Answer 1

Static electricity or electrostatic charge is a deficiency or excess of electrons which occurs on ungrounded or insulating surfaces.

Question 2

Negative and positive charges

Answer 2

Like charges repel, unlinke charges attract. The closer the charges. the greater the force between them.

Question 3

Where do charges come from?

Answer 3

Rubbing two materials together can transfer electrons, causing one to become negatively charged and the other positively charged. This process doesn’t create charge but redistributes existing charges on the materials.

Question 4

What are conductors

Answer 4

Conductors are materials that let electrons pass through them. Some of their electrons are so loosely held, to their atoms that they can pass freely between them. These free electrons also make good thermal conductors.

Question 5

Good conductors

Answer 5

Metals, especially silver, aluminium and copper. Also carbon

Question 6

Are non-metals good conductors?

Answer 6

Most non-metals charge poorly or not at all, although carbon is an exception.

Question 7

What are insulators?

Answer 7

Insulators are materials that hardly conduct at all. Their electrons are tightly held to atoms and are not free to move- although they can be transferred by rubbing. Insulators are easy to charge by rubbing because transferred electrons tend to stay where they are.

Question 8

Semiconductors

Answer 8

There are in between materials. They are poor conductors when cold, but much better when warm.

Question 9

Good semiconductors

Answer 9

Silicon and germanium

Question 10

Good insulators

Answer 10

Plastics like PVC, polythene and Perspex. Glass, rubber, dry air.

Question 11

Poor conductors

Answer 11

water, human body, earth

Question 12

What is the electricity in a cable?

Answer 12

The electricity in a cable is a flow of electrons. Most ables have copper conducting wires with PVC plastic around them as insulation.