P4 - Uses of electrostatics

Question 1

Why do paint sprayers charge droplets?

Answer 1

This is because they have the same charge and repel each other and spread out to give an even coverage.

Question 2

What are the main uses of static electricity?

Answer 2

• defibrillator
• paint spray
• crop sprayer
• photocopier

Question 3

How do electrostatic dust precipitators work?

Answer 3

1) metal plates and a grid are put into a chimney and connected to voltage so the grid becomes negatively charged
2) the plates are earthed and are positively charged
3) as the dust particles pass the grid they become negatively charged
4) the dust particles are attracted to the plates because opposite charges attract

Question 4

How does paint spraying use static electricity?

Answer 4

1) the spray gun is charged
2) all the paint particles become charged with the same sign of charge as the gun
3) like charges repel so the paint particles move away from each other giving a fine spray
4) the object being painted is given the opposite charge to the paint
5) this means the paint is attracted to the object

Question 5

What is defibrillation?

Answer 5

Defibrillation is a procedure that restores a regular heart rhythm by delivering an electric shock through the chest wall to the heart.

Question 6

How does a defibrillator work?

Answer 6

1) two paddles are charged from a high voltage supply
2) they are then placed firmly on the patients chest to ensure a good electrical contact. A conducting gel is usually applied first
3) electric charge is passed through the patient to make their heart contract

Question 7

How is the operator protected in defibrillation?

Answer 7

The paddles have insulating plastic handles.

Question 8

What are the advantages to electrostatic paint sprayers?

Answer 8

• reduction in wasted paint
• paint covers awkward places
• an object receives an even coat of paint