Mains Electricity

Question 1

What is the movement of electrons in a alternating current?

Answer 1

The electrons shunt back and forth, changing direction.

Question 2

What does DC stand for?

Answer 2

Direct current

Question 3

Which side of the battery do electrons move from and to?

Answer 3

From the negative to the positive side of the battery.

Question 4

What is the movement of electrons in a direct current?

Answer 4

The electrons move in one direction around the circuit.

Question 5

What colour is the earth wire?

Answer 5

Green and yellow

Question 7

What colour is the neutral wire?

Answer 7

Blue

Question 9

What are cables made of?

Answer 9

Flexible plastic

Question 11

What is the mains frequency?

Answer 11

50Hz

Question 12

Why do appliances with metal cases have a three core wire?

Answer 12

They contain an earth wire which prevents the case becoming love and electrocuting someone.

Question 13

Why are the pins brass?

Answer 13

Brass is a good conductor

Question 14

What must the cables be connected to in the plug?

Answer 14

The correct terminal

Question 15

What should the rating on fuses be?

Answer 15

It should be higher than the normal working current for the appliance.

Question 16

What is a circuit breaker?

Answer 16

An electromagnetic switch which cuts off the supply if the current is too big.

Question 17

What colour is the live wire?

Answer 17

Brown

Question 18

What does AC stand for?

Answer 18

Alternating current

Question 19

What are the disadvantages of fuses?

Answer 19

• Do not respond instantly

* Has to be replaced when blown.

Question 20

How to calculate power of an appliance

Answer 20

P= I x V

Power= Current(A) x Potential difference/voltage(V)

Question 21

Why are cables different sizes?

Answer 21

They are used for different purposes. The thicker the cable, the more current is carried.

Question 22

What does a RCCB do?

Answer 22

It detects a difference of current between the live and neutral wired and breaks the circuit

Question 23

What is electrical power?

Answer 23

The energy transferred to a device each second.

Question 24

What is an electric current?

Answer 24

The rate of flow of charge

Question 25

What happens in a resistor?

Answer 25

Electrical energy is transferred making the resistor hotter

Question 26

What are some electrical dangers?

Answer 26

• Electrical faults can cause electric shocks and fires
• Overloading sockets is a fire risk
• Don’t touch bare wires or terminals more than 30V

Question 27

What is a fuse?

Answer 27

It contains a thin wire which melts if too much current passes through it, cutting off the current.

Question 28

What should be considered when choosing an electrical appliance?

Answer 28

• Power
• Efficiency
• Cost

Question 29

What are the advantages of low energy light bulbs?

Answer 29

• More efficient

* Last longer

Question 30

What are the advantages of circuit breakers?

Answer 30

• Fast action

* Can be reset

Question 31

What is the mains voltage?

Answer 31

230V

Question 32

What is the equation relating charge, current and time?

Answer 32

Q=I x t

Charge(C)= current(A) x time(s)

Question 33

Why is the cover of a plug plastic?

Answer 33

Plastic is a good insulator