Static Electricity

Question 1

How does static electricity occur?

Answer 1

When electric charges are transferred onto or off the surface of an object.

Question 2

How do objects become negatively charged?

Answer 2

When electrons move onto the object to another object (e.g. a cloth) due to friction.

Question 3

How do objects become positively charged?

Answer 3

When electrons move off the object to another object (e.g. cloth) due to friction.

Question 4

What are the two ways something can be statically charged?

Answer 4

• Through induction

- Through friction

Question 5

How can electric shocks occur?

Answer 5

• Electrons can be transferred onto clothing via friction.
• The electrons stay on your clothes because the materials are insulators.
• If you touched a metal handle, for example, the electrons on your hand can now conduct to earth, which gives you an electric shock.

Question 6

How do lightning strikes occur?

Answer 6

1) Ice particles in the clouds gain electrons from other ice particles by friction.
2) The bottom of the cloud gains electrons and a negative charge.
3) Electrons in the ground are repelled by the bottom of the cloud.
4) Lightning jumps to earth as a spark of electrons.

Question 7

What does electrostatic induction involve?

Answer 7

An opposite charge is induced on the surface of a neutral insulator by a charged insulator.

Question 8

Describe how a balloon with a negative charge will stick to a wall?

Answer 8

This occurs through electrostatic induction.

• The balloon has a negative charge
• When the balloon touches the wall, the electrons in the wall are repelled away because of electrostatic attraction.
• This creates a positive charge on the wall.

Question 9

How are electrostatics used in insecticide sprayers?

Answer 9

• The nozzle of the sprayer is connected to an electrical supply.
• The droplets will gain the same kind of static charge when leaving the nozzle.
• The droplets repel from each other so they spread out, making the spray spread out evenly.

Question 10

How are electrostatics used in paint sprayers?

Answer 10

• The nozzle of the sprayer is connected to an electrical supply.
• The droplets will gain the same kind of static charge when leaving the nozzle.
• The object that is about to be painted is given the opposite charge.
• The paint is attracted to the object being painted, therefore wasting less paint.

Question 11

Why can electrostatics become dangerous?

Answer 11

Electrons are transferred to objects via friction, like aircraft in the air. This is dangerous because a spark may occur from the nozzle of the plane and a fuel tanker because the fuel tanker is grounded. This can ignite the fuel vapours and cause an explosion.
- To avoid this, an earthing wire is connected between the aeroplane and the ground to ensure a safe movement of electrons.

Question 12

In which direction do electrical fields from a positive point radiate?

Answer 12

Outwards.

Question 13

In which direction do electrical fields from a negative point radiate?

Answer 13

Inwards.

Question 14

How does an electrical field travel in oppositely charged parallel panels?

Answer 14

It travels in parallel lines from the positive panel to the negative panel.