Electricity

Question 1

What is the function of fuses?

Answer 1

It prevents the risk of fires and electric shocks

Question 2

How to fuses work?

Answer 2

1. If live touches metal case, then because the case is earthed, a big current flows thru LIVE WIRE, the CASE and EARTH WURE
2. Surge in current MELTS fuse which cuts off LIVE SUPPLY
3. this ISOLATES the whole appliance making it impossible to get electric shock from Case and prevents FIRE caused by heating effect of large current

Question 3

How does earthing protect the device or user?

Answer 3

The case is attached to an Earth wire to reduce danger of electric shock.
An earthed conductor can never be live

Question 4

How does double insulation protect the device or user?

Answer 4

• When appliance has plastic casing and no metal parts showing
• Plastic is insulator, so stops current flowing so you can’t get a shock.
• Anything with double insulation doesn’t need an Earth wire

Question 5

Why are circuit breakers better than fuses?

Answer 5

1. Easily reset by flicking a switch or pushing a button so they don’t need to be replaced
2. Are able to react much faster

Question 6

What’s the function and colour of the LIVE wire

Answer 6

BROWN
carries current to appliance at high voltage (around 230V)

Question 7

What’s the colour and function of NEUTRAL wire

Answer 7

BLUE
completes circuit and carries current away from appliance
Nearly 0V

Question 8

What’s the colour and function of the EARTH wire?

Answer 8

GREEN & YELLOW
Safety wire & connects metal case of appliance to Earth
Stops a fault making case live

Question 9

What’s the difference between an AC and DC?

Answer 9

AC constantly switches direction in the circuit, but DC remains in 1 direction

Question 10

Define CURRENT

Answer 10

RATE of flow of charge

Question 11

What is the formula for charge?

Answer 11

Q = IT

Question 12

Define potential difference

Answer 12

The amount of energy transferred per unit of charge passing through the terminals

Question 13

what is the equation linking potential difference, energy transferred and charge?

Answer 13

V = E/Q

Question 14

Define resistance

Answer 14

the opposition to current

Question 15

Describe current in series

Answer 15

the same value at any point
- number of electrons per second that passes through one part of the circuit is the same number that passes through any other part

Question 16

What does the amount of current in a circuit depend on?

Answer 16

1. The voltage of the power source
2. The number (and type) of components in the circuit

Question 17

current in parallel

Answer 17

the current is conserved

Question 18

In what direction does convectional current flow?

Answer 18

Positive to Negative

Question 19

voltage in series

Answer 19

shared between the components

Question 20

voltage in parallel

Answer 20

The potential difference across each component is the same

Question 21

what are some advantages of a series circuit

Answer 21

1. All of the components can be controlled by a single switch

2.Fewer wires are required

Question 22

The disadvantages of a series circuit are…

Answer 22

1.The components cannot be controlled separately

2. If one component breaks, they will all stop working as well

Question 23

Advantages of parallel circuits

Answer 23

1. The components can be individually controlled, using their own switches
2. If one component breaks, then the others will continue to function

Question 24

Disadvantages of parallel circuits

Answer 24

1. Many more wires involved so much more complicated to set up
2. All components have the same voltage as the supply, so harder to control if components need to have different voltages

Question 25

Resistors in Series

Answer 25

the total (or combined) resistance is equal to the sum of their individual resistances