Electricity

Question 0

What does 50 Hz mean

Answer 0

50 cycles per second, current changes direction 50 times

Question 1

What do a.c and d.c stand for

Answer 1

Alternating current (direction of current changes)
Direct current (direction of current remains the same)

Question 2

Equations for frequency/time period

Answer 2

T= 1/F
TF=1
F= 1/T

Question 3

Name the three wires in a plug and there colours

Answer 3

Earth wire- brown
Live wire- blue
Neutral wire- green/yellow

Question 4

What’s does the earth wire do

Answer 4

Prevents the plug short circuiting and melting

Question 5

Mains cable

Answer 5

Connects the plug to the mains and supplies electricity

Question 6

Live wire

Answer 6

Active write connects fuse to mains

Question 7

Fuse

Answer 7

Supplies a current

Question 8

What are the three fuse sizes

Answer 8

3A, 5A and 13A

Question 9

What wire attaches to the fuse

Answer 9

The live wire

Question 10

What sort of the appliance is attached to the earth wire

Answer 10

The outer metal casing

Question 11

What are the voltages of the wires

Answer 11

Live- 240 V

Neutral and earth- 0V

Question 12

Where would the current travel if there was a fault with the live wire

Answer 12

Outer metal casing

Question 13

What happens when too high a current flows through a wire and why

Answer 13

It would heat up and melt because the wire is not thick enough so the electrons collide a lot which converts kinetic energy into thermal energy

Question 14

What equation links power, voltage and current

Answer 14

Current= power/voltage

Question 15

Why does the Heating Element heat up when current flows through it

Answer 15

It has a high resistance so electrons struggle to through it at a high current because high resistance= low creepy so there are too many collisions and wire overheats and melts

Question 16

What is 1kwh equal to

Answer 16

Energy used by 1000 W appliance in an hour

Question 17

What’s the problem with a fuse which is too big

Answer 17

If the current increases due to a fault then this wouldn’t be detected until very high increase so could damage appliance

Question 18

Circuit breaker

Answer 18

The break the circuit in the presence of a large current

Question 20

Describe what how a circuit breaker works

Answer 20

Electromagnet gets stronger as the current increases so when it gets too strong the iron bolt is pulled out and the circuit is broken

Question 21

How is a circuit breaker reset

Answer 21

The button is pressed which pushes the iron bolt back into place and always the iron bolt to fit back into it