P2-Electricity

Question 1

What is current

Answer 1

The flow of electrical charge

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Question 2

What is the ammeter

Answer 2

It measures the current flowing through the test wires

– the meter must always be placed in a series with whatever you’re investigating

Question 3

What is a volt meter

Answer 3

Measures the potential difference across the test wire

– must always be placed in parallel around What ever you’re investigating

Question 4

What is the relationship between current and resistance in an ohmic conductor

Answer 4

The current is directly proportional to the potential difference

Question 5

What is the relationship between current and potential difference in a filament lamp

Answer 5

As the current increases the temperature of the filament increases , So the resistance increases
– this means that less current can flow per unit of potential difference

Question 6

What is the relationship between current and potential difference in a diode

Answer 6

Current will only flow through diet One Direction however the diet has a very high resistance in the reverse direction

Question 7

What is a light dependent resistor

Answer 7

There is it that is dependent on the intensity of light
– in bright light the resistance falls
– in darkness the resistance is highest

Question 8

What is a thermistor

Answer 8

I thermostat is a temperature dependent resistor
– in hot conditions their resistance drops
– in cool conditions the resistance goes up

Question 9

How is the potential difference distributed in a series circuit

Answer 9

The potential difference is shared between various components and therefore it always adds up

Question 10

How is the current distributed in a series circuit

Answer 10

It is the same everywhere

– the size the current in each component is the same

Question 11

How is the resistance distributed in a series circuit

Answer 11

Resistance adds up

Question 12

How is potential difference distributed in a parallel circuit

Answer 12

Potential difference is the same across all components

– it’s equal

Question 13

How is currently distributed in a parallel circuit

Answer 13

Current is shared between branches

– it adds up

Question 14

What happens when you add a resistor in a parallel circuit

Answer 14

The total resistance decreases
–Because the potential difference is the same across all components and therefore by adding another loop the car in a small direction to go in and by increasing the current it needs a decrease in resistance

Question 15

Happens when you add a resistor in a series circuit

Answer 15

The resistance increases
– this because by adding a resistor in series, but he resists have to share the potential difference
– the potential difference across a resistor is lower so the current through each resistor it’s also our
– in a series circuit the current is the same everywhere so the total current in the circuit is reduced when a resistor is added
-This means the total resistance of the circuit increases

Question 16

What is DC

Answer 16

Direct current – it is a current that always flows in the same direction

Question 17

What is AC

Answer 17

Alternating-current

– produced by alternating voltages which change direction

Question 18

What is the colour of the live wire and what is its potential difference

• What does it do

Answer 18

Brown – 230

*It provides the alternating potential difference

Question 19

What colour is the neutral wire ,what does it do And what is its potential difference

Answer 19

Blue – the neutral wire completes the circuit and carries away current
– it has a potential difference of 0 V

Question 20

What colour is the Earth wire, what does it do and what is its potential difference

Answer 20

Green and yellow – it is used for protecting the wiring, and for safety – it stops appliance causing from becoming live
– It has a potential difference of 0V

Question 21

Why can’t I live fire give you a potential shock

Answer 21

Your body is at 0 V – This means that if you touch the livewire a large potential difference is produced it across your body and a current flows through
– this causes a large electric shock
– your body provides a link between the supply of the Earth
– even if I plug socket or light switch is turned off there is still a danger and electric shock, I can’t as I’m flying with a still a potential difference in the live wire

Question 22

Voltage is the UK mains supply

Answer 22

230 V

Question 23

What is a power rating

Answer 23

They are labelled with the maximum safe power that they can operate at
-It was a toast to the maximum out of energy transferred between stores per second when applied is in use

Question 24

What is the National Grid

Answer 24

Giant system of cables and Transformers that cover the UK and connect power stations to consumers

Question 25

Why are step up stepdown transformers used

Answer 25

By having a high voltage and low current – less current means less energy is lost through heating to the wire
- It is therefore much cheaper

Question 26

What is the function of step up and stepdown Transformers

Answer 26

The potential difference is increased and decreased for safe levels to the houses