4.2.1 Electrical charge

Question 1

What is the S.I unit of charge?

Answer 1

Coulombs (C)

Question 2

What is charging by induction?

Answer 2

A charge that “appears” or is induced on an uncharged object because of a charged object nearby.

Question 3

Describe an experiments to show the production and detection of electrostatic charges.

Answer 3

Experiment 1

1. Rub a cloth and balloon together (the electrons from the cloth go onto the balloon. The cloth is left with a positive charge while the ballon is left with a negative charge)
2. Put the ballon near an open tap with running water
3. The water should bend towards the balloon. (The positive particles in the water are being attracted to the negatively charged balloon)

Experiment 2
Repeat 1
2. Place the balloon on a wall.
3. The balloon should stick to the wall. (The negative charge of balloon is attracting the positive particles in the wall resulting in it sticking to the wall)

Question 4

What are the two charges that exist?

Answer 4

Positive and negative

Question 5

What happens to a charged body/object?

Answer 5

It has lost or gained electrons

Question 6

What is the difference between conductors and insulators?

Answer 6

Conductors conduct electricity / allows it to pass through since it has free electrons. (e.g. copper and iron)
Insulators don’t allow electricity through them/ allow very little since it doesn’t have a lot of free electrons; (e.g. plastic and wood)

Question 7

What is the direction of an electrical field at a point?

Answer 7

It is the direction of the force acting on a positive charge at that point.
In other words, it comes from the positive (going out of the positive) towards the negative (into the negative)

Question 8

Describe the field patterns between parallel plates.

Answer 8

Perpendicular field lines from the particles in the positive plate to the particles in the negative plate.

Question 9

Describe the field patterns around a conducting sphere.

Answer 9

You will have field lines coming from or going into the point depending on the nature of the charge.

Question 10

Describe the field lines around a point.

Answer 10

A positive and negative point have field lines going from the positive side to the negative sides.
Points with opposing charges have field lines pushing each other.