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GCSE Physics*** > Mains Electricity > Flashcards

Flashcards in Mains Electricity Deck (20):
1

What danger can frayed cables cause ?

The insulation has warn down exposing live wires, and therefore electricity can be conducted from them

2

What danger can longer cables cause ?

There is a higher resistance with longer wires, making it a higher risk of them over heating

3

What danger can damaged plugs cause ?

Create a risk that some of the safety features may be broken

4

What danger can water around appliances cause ?

Water conducts electricity, therefore the electricity/current can flow through the water, electrocuting someone or creating a fire

5

What danger can metal objects in plugs cause ?

Metal conducts electricity, therefore the current can flow through the metal and electrocute someone

6

How does insulation protect a user ?

It protects the user from electrocution by surrounding electrical conductors with insulators

7

What is double insulation ?

The live wire is surrounded by two casings, so the wire cannot touch the outer casing therefore no charge can be passed onto the user if touched

8

What are fuses ?

They are sections of wire in the circuit that melts if the current gets too high.

• when the wire melts, no current can flow through the circuit. This protects an electrical circuit from damage due to excess current

9

What are circuit breakers ?

They have an electromagnet that is activated when the current goes above a certain limit. The electromagnet pulls an iron switch towards it, this opens the switch and breaks the circuit.

10

What does an earthing wire do ?

It creates a safe route for the current to flow through if the live wire touches the casing

11

What is an earthing wire ?

A low-resistance path for electricity to flow

12

What does a resistor do ?

Slows down the movement of electrons

13

Is current a resistor ?

Yes

14

What energies are converted in a resistor ?

The Kinetic energy that was moving them, is converted into heat energy

• this is what causes heating of the wires

15

What is joule heating ?

Joule heating is due to electrical resistance, this can be used in heating and lighting

16

Equation for power, energy and time

Power = current x voltage

17

Equation for energy transfer



Energy = current x voltage x time
Transfer

18

Equation for power current and voltage

Power = current x voltage

19

Describe AC

• alternating current
• it is normally high-voltage
• it comes from generators and is the electricity supplied to the home

20

Describe DC

• direct current
• it is normally low-voltage
• it comes from batteries and is used in most electrical devices