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physics GCSE > electricity test revision > Flashcards

electricity test revision Flashcards

topics: - Direct and alternating potential difference - Mains electricity and the national grid - Power and energy transfers - Different energy sources - Circuit diagrams - Electric components

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1
Q

The role of an oscilloscope is to what?

A

Display how voltage changes with time

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2
Q

what’s an oscilloscope?

A

it’s a device that produces and displays potential difference first time graphs on the monitor, showing the change of voltage with time

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3
Q

what is an Alternating current is caused by?

A

this is caused whenever we use an alternating potential difference which causes the current to periodically change direction.

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4
Q

what is an Direct current is caused by?

A

caused by a constant flow of electrons in one direction, typically produced by sources like batteries or cells.

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5
Q

All countries use alternating current as their mains supply.
In the UK, the mains supply has a frequency and voltage of what

A

Frequency = 50Hz

Voltage = 230 V - 240 V

this means that the potential difference fluctuates from
240v to -240v 50 times per second

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6
Q

what an Alternating current?

A

it’s a current that changes direction repeatedly
(constantly swapping back and fourth)

meaning it fluctuates between positive and negative

It is supplied by mains electricity.
e.g. plug sockets , powers computers/ kettles etc…

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7
Q

what a Direct current?

A

it’s a current that is always flowing in one/same direction only.

meaning it’s either negative or positive (only one)

It is supplied by cells or batteries.

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8
Q

Electricity demand varies during the day and generally peaks when?

A

the afternoon
as that’s when people come back from school/work.
time where people would cook food or watch tv and play games

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9
Q

The formula for electric power is?

A

power = voltage × current

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10
Q

what is the symbol formula for electric power?

A

P = IV

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11
Q

what does High currents effect the wire?

A

High currents cause the wire to heat up, meaning that energy is lost as heat to the surroundings.

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12
Q

Step-up transformers are used for what?

A

Increase the voltage and decrease the current

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13
Q

Step-down transformers are used for what?

A

Decrease the voltage and increase the current

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14
Q

How electric power gets to our homes (simple 5 points)

A

Electric power is generated at a power station.

Step up transformers increase the voltage and decrease the current.

The electric power is transmitted via the national grid at low current which minimises power loss.

Step down transformers decrease the voltage and increase the current near our homes.

Electric power is wired into our homes at a voltage that is relatively safe to use.

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15
Q

where does most of our electricity come from and how?

A

power stations.

They generate loads of heat through:
- Burning fuels: Fossil fuels like coal, oil, or gas.
- Nuclear reactions: Using nuclear fission to release energy.
- Geothermal energy: Heat from the Earth’s interior.

This heat is used to produce steam, which drives turbines. The turbines then spin generators, converting thermal energy into electrical energy.

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16
Q

How do power stations handle surges in electricity demand?

A

Power stations usually operate with spare capacity, meaning they run below their maximum power output. This allows them to quickly increase electricity production to meet surges in demand.

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17
Q

A power source for an electric circuit could be a…

A

Cell
Battery

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18
Q

Current

A

‘I’
a measure of the flow of electrons around a circuit

similar like the flow of water

Amps (A)

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19
Q

Potential difference

A

‘v’
Potential difference is the force driving the flow of electrons around a circuit

like the pump that forces the water along the pipe

also known as ‘Voltage’
MEASURED IN ‘V’

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20
Q

In ‘conventional current’, we say that the electrons flow from

A

Positive terminal ➔ negative terminal

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21
Q

Resistance

A

‘R’

Resistance is everything that resists or opposes the flow of electrons in a circuit

similar to a plug blocking the water flow

measure in Ohms (Ω)

22
Q

For wires and resistors, increasing the temperature will __________ the resistance.

A

increase

As temperature increases, all of the ions in the metal vibrate faster, which makes it harder for electrons to pass along the wire (or in other words, the resistance increases).

23
Q

Diodes

A

Only allow current to flow one way around a circuit

24
Q

charge

A

‘Q’

a measure of the total currents that flowed within a certain period of time

measured in coulombs (C)

25
Q

charge in an water analogy

A

charge could be the total amount of water that has flowed down the hill within a certain time

26
Q

formula for charge

A

charge = current × time

27
Q

The units for charge are

A

Coulombs (C)

28
Q

The symbol formula for charge

A

Q= It

29
Q

A light emitting diode will…

A

Only allow current to flow in one direction

Emit light when current flows through it

30
Q

ammeters

A
  • They are added to a circuit in series
  • They measure current
30
Q

A resistor whose resistance decreases when temperature increases is a…

A

Thermistor

31
Q

Which of the following statements about voltmeters are true?

A

They measure potential difference

They are added to a circuit in parallel

32
Q

Which type of resistor allows us to easily adjust its resistance?

A

Variable resistor

33
Q

A resistor which cannot vary the amount of resistance it provides is a…

A

Fixed resistor

34
Q

In which type of resistor does the resistance vary with light intensity?

A

Light dependent resistor (LDR)

35
Q

The resistance of a thermistor decreases when the temperature _______.

A

increases

36
Q

Name the three wires that are normally present in UK plugs.

A

Live wire
Neutral wire
Earth wire

37
Q

Wires are made of…

A

copper and coated in a layer of insulating plastic

38
Q

Which wire prevents the electrical casing from becoming live?

A

Earth wire

39
Q

Which wire supplies the current to the appliance?

A

live wire

40
Q

Which wire completes the circuit, allowing current to flow?

A

Neutral wire

41
Q

What is the voltage of the neutral wire?

A

0 V

42
Q

Which two wires have the same voltage?

A

The earth wire and neutral wire are both at 0 V, whereas the live wire is at 230 V.

43
Q

In a series circuit, the potential difference of the battery is…

A

…Shared across all of the components

44
Q

Series circuits L

A

Series circuits only have a single loop.

45
Q

Parallel circuits L

A

Parallel circuits have more than one loop.

46
Q

In a series circuit, the current is

A

The same everywhere in the circuit

47
Q

In a series circuit, the total resistance is ________ the sum of the individual resistances of each component.

A

equal to

48
Q

Ohm’s law, which describes the relationship between voltage, current, and resistance is:

A

V=IR

49
Q

In a series circuit, components with a greater resistance will always have a ________ share of the voltage.

A

greater

50
Q

notes

A

The total current is shared between all of the parallel loops.

The sum of the current in each loop is equal to the total current.

51
Q
A

physics GCSE (6 decks)

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