Physics-Paper1-Electricity

Question 1

What is direct circuit?

Answer 1

The flow of electrons is consistently in one direction around the circuit

Question 1

List all the electric component (14)

Answer 1

https://www.bbc.co.uk/bitesize/guides/zgvq4qt/revision/1

Question 2

What is an alternating circuit?

Answer 2

The direction of electron flow continually reverses

Question 3

What is charge?

Answer 3

A property of a body which experiences a force in an electric field. Charge is measured in coulombs (C)

Question 4

What is current?

Answer 4

One amp is the current that flows when one coulomb of charge passes a point in a circuit in one second.

Question 5

What is the equation that link charge, current and time?

Answer 5

charge = current × time

Q=It

Question 6

What is used to measure current?

Answer 6

Ammeter

Question 7

What is used to measure potential difference?

Answer 7

Voltmeter

Question 8

What is potential difference?

Answer 8

The difference of electrical potential between two points

Question 9

How must a voltmeter place in a circuit?

Answer 9

In parallel

Question 10

How to calculate the voltage using energy and time?

Answer 10

Potential difference=Energy/Time

V=E/T

Question 11

What does V=E/T mean?

Answer 11

One volt is the potential difference when one coulomb of charge transfers one joule of energy.

Question 12

What is the equation that links potential difference, current and resistance?

Answer 12

potential difference = current × resistance

V=IR

Question 13

Suggest a method to investigate how changing the length of the wire affects its resistance

Answer 13

1. Connect the circuit as shown in the diagram above.
2. Connect the crocodile clips to the resistance wire, 100 centimetres (cm) apart.
3. Record the reading on the ammeter and on the voltmeter.
4. Move one of the crocodile clips closer until they are 90 cm apart.
5. Record the new readings on the ammeter and the voltmeter.
6. Repeat the previous steps reducing the length of the wire by 10 cm each time down to a minimum length of 10 cm.
7. Use the results to calculate the resistance of each length of wire by using R = V/I, where R is resistance, V is voltage and I is current.
8. Plot a graph of resistance against length for the resistance wire.

Question 14

How to calculate the current in a series circuit?

Answer 14

• All electrons in that loop form one current. An ammeter will measure the same current wherever it is placed in the circuit.
• I1=I2=I3

Question 15

How to calculate the potential difference in a series circuit?

Answer 15

• The potential difference supplied is equal to the total of the potential differences across all other components
• Vs=V1+V2

Question 16

How to calculate the resistance in a series circuit?

Answer 16

• The resistances are added together
• R total=R1+R2

Question 17

How to calculate the current in a parallel circuit?

Answer 17

• Since there are different loops, the current will split as it leaves the cell and pass through one or other of the loops.
• An ammeter placed in different parts of the circuit will show how the current splits.
• I1=I2+I4=I3

Question 18

How to calculate the potential difference in a parallel circuit?

Answer 18

• The potential difference supplied is equal to the potential differences across each of the parallel components
• Vs=V1=V2

Question 19

How to calculate the resistence in a parallel circuit?

Answer 19

If resistors are connected in parallel the supply current is divided between them. The overall resistance is reduced as the current may follow multiple paths.

Question 20

What is the equation that links power,current and potential difference?

Answer 20

power = current × potential difference
P=IV

Question 21

What is the equation that links power,current and resistence?

Answer 21

power = current2 × resistance

P=I^2R

Question 22

What is the potential difference and the frequency of the main electrical supply in the UK?

Answer 22

230V and 50Hz

Question 23

What colour is the live wire?

Answer 23

Brown

Question 24

What does the live wire do?

Answer 24

Provides the alternating potential difference from the supply

Question 25

What colour is the earth wire?

Answer 25

Green and yellow stripes

Question 26

What does the neutral wire do?

Answer 26

Complete the circuit

Question 27

What does earth wire do?

Answer 27

• The earth wire is connected to the case and is attached to a metal plate or water pipe underground.
• As the wire is made of copper, the earth wire provides a low resistance path to the ground.
• In the event of a fault, the live current passing through the case will follow this path to the ground instead of passing through a person.

Question 28

What colour is the neutral wire?

Answer 28

Blue

Question 29

What is the National Grid?

Answer 29

A system of cables and transformers linking power station to consumers

Question 30

What does the step up transformer do?

Answer 30

• A step-up transformer is used to increase the voltage, causing the current to decrease
• Less current means less energy is lost through heating the wire

Question 31

What should appear on a voltage-time graph when there is a direct circuit?

Answer 31

On a voltage-time graph this would appear as a straight horizontal line at a constant voltage

Question 32

What should appear on a voltage-time graph when there is a alternating circuit?

Answer 32

On a voltage-time graph, this would appear as a curve alternating between positive and negative voltages. The positive and negative values indicate the direction of current flow.