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AQA GCSE Physics 2016on > P2 Electricity > Flashcards

Flashcards in P2 Electricity Deck (37)
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1

What is the National grid?

The National Grid is used to distribute electricity around the country from power stations to consumers. It is the network of pylons and wires you see high above you across the country.

2

Current is a measurement of.......

........the rate of charge flow.

3

A step-up transformer steps the voltage up and the current ..........

....decreases

4

Explain why transformers are used in the National Grid.

Transformers allow the power to stay high because a high voltage means the current can be lowered. This stops the wire getting warm and losing energy to the surroundings.

5

What is AC/DC apart from an Australian rock band?

DC = Direct current AC = Alternating Current

6

What is the voltage and frequency of the mains?

In the UK, the frequency of mains electricity is 50 Hertz. The voltage of mains electricity supplied to UK homes is 230 V.

7

What is the name and pd of the blue wire?

The neutral wire at 0V

8

How would you calculate power?

power = current x voltage

9

What is the rule for voltage in series circuits?

The voltage from a battery is shared between all the components in a series circuit.

10

What is the rule for current in series circuits?

The current has only one route in a series circuit and all ammeters would show identical current.

11

How does the length of a wire affect its resistance?

As the length increases the resistance also increases.

12

Why does an increase in temperature in a wire increase its resistance?

As a metal heats up their resistance increases because their positive metal ions vibrate more and so block the flow of electrons.

13

What are the steps through the National Grid from the power station to your home or school

Electricity from a power station goes to:- Step-up transformers (you will find out about those next) - High-voltage transmission lines/wires - Step-down transformers - Consumers (i.e. your home, school, supermarket)

14

What is the difference between direct current (d.c.), and alternating current (a.c.)?

Direct current (d.c.) is an electric current that always flows in one direction. Alternating current (a.c.) is an electric current that is constantly changing direction.

15

Resistance is........

..a measure of how much a conductor prevents the flow of electrons.

16

The voltage of a battery or cell is a measure of .......

....the energy given to the electrons so that they can flow around the circuit.

17

How would you calculate electrical energy?

electrical energy = power x time

18

What is the equation to find charge?

Charge = current x timeQ = It

19

What is the name and job of the green and yellow wire?

The earth wire is a safety wire that is needed to earth appliances with a metal case. This makes it safer to touch the appliance if it develops a fault.

20

What is the name and pd of the brown wire?

The live wire alternates between a negative and positive voltage of 230V

21

Why are the wires are made of copper?

Copper is a good electrical conductor.

22

What is meant by a step-up and step-down transformer?

Step-up transformers increase voltage and step-down transformer decrease voltage?

23

What is a transformer?

A transformer is a device to change voltage in a circuit.

24

Current is measured in.....

.......Amps (short for Amperes).

25

Electrical charge is measured in.....

Coulombs

26

What is the rule for current in parallel circuits?

The current is shared between all the components in a parallel circuit because there are different routes that the current can take .

27

What equation would you use to calculate voltage?

voltage = current x resistance

28

Give an example of a source of a.c. and a source of d.c.

Direct current is produced by cells and batteries. Alternating current is produced by most generators and is used in mains electricity

29

What is the rule for voltage in parallel circuits?

The voltage from a battery is identical for all the components in a parallel circuit.

30

Give 2 equations to calculate electrical energy?

electrical energy = power x timeelectrical energy = charge x voltage