Ch.8.1

Question 1

Electricity is very important in our ____________________________.

Answer 1

modern lives

Question 2

We use electricity at _______________ and ________________ every day.
We use it to ____________________________, __________________________ and _____________________________. We also use it for _____________________ and ______________________.

Answer 2

home, school, light our rooms, cook our food, wash our clothes, transportation, communications

Question 3

For an electrical appliance to work:
—it must be
—there is

Answer 3

connected to a source of electricity; and

a path for electricity to flow

Question 4

What is an electric circuit? What do we call in for short?

Answer 4

It is the path that electricity flows through. We call it a circuit for short.

Question 5

An electric circuit has three basic components:
1.
2.
3.

Answer 5

Source of electricity and electrical energy
Device using electrical energy
Wire connecting different parts of the circuit together

Question 6

Two conditions needed for electricity to flow:
1.
2.
Conclude.

Answer 6

—Complete path from one end of the electric cell to the other
—There are electric cells in the circuit
Conclusion: A closed circuit with a source of electrical energy is required for electricity to flow

Question 7

Please describe a closed circuit.

Answer 7

It is a circuit with a complete path for electricity to flow from one end of the electric cell the other other.

Question 8

Describe an open circuit.

Answer 8

It is a circuit with a gap in it, so that electricity cannot flow.

Question 9

Please describe the energy conversion in a closed circuit.

Answer 9

chemical energy in the electric cell ➞ electric energy ➞ light bulb and thermal energy released by the light bulb

Question 10

What are the energy converters in the energy conversion in a closed circuit?

Answer 10

The electric cell and light bulb.

Question 11

Please name four types of cells.

Answer 11

Primary cells, secondary cells, dry cells and wet cells.

Question 12

Name the difference between primary and secondary cells.

Answer 12

Primary cells are non-rechargeable, while secondary cells are.

Question 13

Name the difference between dry cells and wet cells.

Answer 13

Dry cells is commonly used in daily life, while wet cells are used in cars.
Dry cells are in the form of a paste, while wet cells are in the form of a battery solution.
Dry cells come in different sizes, while wet cells don’t.

Question 14

What are electrical conductors?

Answer 14

Materials that allow electricity to flow through them.

Question 15

Name 4 examples of electrical conductors.

Answer 15

metals, mineral water, graphite, salt solutions/ acids.

Question 16

Name 5 examples of metals that are used to conduct electricity, from the best conductor to the worst.

Answer 16

1. Silver (but it’s expensive!)
2. Copper
3. Bronze, iron (will rust), aluminium

Question 17

Can pure/ distilled water conduct electricity?

Answer 17

No.

Question 18

Besides metals, some other materials can also ___________________ ___________________, but _________________________________________________.

Answer 18

conduct electricity, not as well as metals can

Question 19

What are electrical insulators?

Answer 19

Materials that do not allow electricity to flow through them.

Question 20

Name 3 examples of electrical insulators.

Answer 20

plastic, glass, wood

Question 21

What are the handles of the tools used by an electrician made of? Why are they made of the material?

Answer 21

Plastic. To prevent electric shock as plastic is a electrical insulator.

Question 22

A switch can be used to ___________________ or ___________________ a circuit.

Answer 22

open, close

Question 23

When a switch is closed, ____________________________________________________________________________. In other words, the circuit ___________________________________________________________________.

Answer 23

the path for electricity to flow in the circuit is complete.

becomes a closed circuit and thus electricity can flow through it.

Question 24

When a switch is open, ____________________________________________________________________________. Thus, _______________________________________________.

Answer 24

there is a gap in the circuit and the circuit becomes incomplete.
electricity cannot flow

Question 25

What qualities do electrical insulators have in common?

—

Answer 25

no electrons/ fixed electrons