# Physics (Paper 2) Flashcards

1
Q

(SP8/9)
Energy definition

A

the ability to do work or cause a change

2
Q

Work done definition

A

Energy transferred

3
Q

Equation for work done

A

Force x Distance

4
Q

Work done is measured in

A

Joules

5
Q

Time is measured in

A

Seconds

6
Q

Energy stores/transfers

A

• GPE
• EPE
• Chemical
• Kinetic
• Nuclear
• Electrostatic
• Magnetic

• Thermal
• Sound

7
Q

How is force worked out?

A

Mass x acceleration

8
Q

Contact force definition

A

A force that acts between two touching objects

9
Q

Reaction force definition

A

The force of an object at rest on a surface

10
Q

Air resistance definition

A

the force of an object moving through the air

11
Q

Upthrust definition

A

The force of an object floating on water

12
Q

Non contact force definition

A

A force acting between 2 objects that do not touch

13
Q

Examples of contact forces

A

Upthrust, friction, reaction force

14
Q

Examples of non contact forces

A

Gravity, magnetism and electrostatic force

15
Q

Scalar tells us the…

A

Magnitude (size) of a force

16
Q

Vector tells us the…

A

magnitude and direction of a force

17
Q

What is Newton’s Third Law of Motion?

A

For every action there is an equal and opposite reaction

18
Q

Equilibrium definition

A

When forces are balanced or cancel out

19
Q

Friction definition

A

Force between 2 surfaces sliding

20
Q

Resultant force

A

Overall force acting on an object
(aka net force)

21
Q

Net force definition

A

Sum of the forces applied on object (overall force)

22
Q

Moment definition

A

Turning force

23
Q

Moment equation

A

Force x Distance

24
Q

Clockwise movement is what compared to anti clockwise movement

A

Equal

25
Q

A free body diagram models the

A

Forces acting on an object

26
Q

Examples of vectors

A

• Velocity
• Weight
• Reaction force
• Friction
• (any force)

27
Q

Moment is calculated in

A

Newton metres

28
Q

Equation for Weight

A

Mass x gravitational field strength (10 N/kg)

29
Q

Examples of scalar quantities

A

• Temperature
• Energy
• Speed
• Time

30
Q

(SP10)
Electrical circuit definition

A

a closed path where electrons flow in a wire

31
Q

Series circuit

A

Only has one pathway or loop

32
Q

Parallel circuit definition

A

A circuit in which current can flow through on multiple paths

33
Q

Diode definition

A

A component that only allows current to flow in one direction

34
Q

What is the unit of charge (Q)?

A

Coulomb (C)

35
Q

What is the unit of current?

A

Amperes

36
Q

What does LDR stand for?

A

Light Dependent Resistor

37
Q

What does LDR (Light Dependent Resistor) mean?

A

Resistor that depends on light intensity. As the light intensity decreases the resistance increases and vice versa

38
Q

The direction of current flow is from..

A

the positive terminal to the negative terminal of the power supply

39
Q

Current meaning

A

Rate of the flow of charge

40
Q

Charge =

A

Current x time

41
Q

Energy transferred equations

A

Charge (Q) x voltage (V)
or
Current (I) x Voltage (V) x Time (t)
or
Power (P) x Time (t)

42
Q

Voltage meaning

A

Energy transferred per unit charge
(V = E/Q)

43
Q

What type of circuit are ammeters connected in?

A

Series

44
Q

What component can only be connected in a parallel circuit?

A

Voltmeter

45
Q

Voltage equations

A

V = Current (I) x Resistance (R)
V = Energy transferred (E) / Charge (Q)
V = Power (P) / Current (I)

46
Q

Current is directly proportional to

A

Voltage

47
Q

Unit for resistance

A

Ohms

48
Q

Resistance meaning

A

Opposition to current

49
Q

As resistance increases, what happens to current?

A

Current decreases

50
Q

How to work out the total resistance in a series circuit?

A

Adding up all the individual resistances (Rtotal = R1 + R2 + Rn)

51
Q

How to work out the total resistance in parallel circuits?

A

Reciprocal of each of the resistances added together
(1/Rtotal = 1/R1 + 1/R2 + 1/Rn)

52
Q

Thermistor

A

Resistor that responds to temperature

53
Q

Ohms law

A

Current flowing through a conductor is directly proportional to the voltage (V = IR)

54
Q

Power definition

A

The rate at which energy is transferred per second

55
Q

Unit for power

A

Watts

56
Q

Equations for power

A

P = I (Current) x V (Voltage)
P = I² (Current²) x R (Resistance)
P = E (Energy transferred) / T (Time)

57
Q

(SP8) Kinetic energy equation

A

KE = 0.5 x mass x (speed)²

58
Q

Mass is measured in

A

Kg

59
Q

Weight (and all other forces) is measured in

A

Newtons

60
Q

How does resistance affect current in filament lamps?

A

As the current increases the temperature also increases • Increase in temperature increases the resistance • Causes current to increase at slower rate • (I-V graph has S shaped curve through origin)

61
Q

What’s the relationship between voltage and current in diodes?

A

The current through a diode flows in one direction only • The diode has a very high resistance in the reverse direction so current is unable to flow • (I-V graph slopes upward with nothing shown on bottom side of graph)

62
Q

Relationship between current and voltage in fixed resistors

A

• Current is directly proportional to voltage • Temperature remains constant • Resistance remains constant • (I-V graph presented as a straight line through origin as it obeys Ohm’s law)

63
Q

AC meaning

A

Alternating current • Current that changes its direction back and forth

64
Q

DC meaning

A

Direct Current • Current that flows in the same direction (positive terminal to negative terminal)

65
Q

Characteristics of the UK domestic supply

A
• Supply is AC
• Frequency is 50 Hz
• Voltage is 230 V
66
Q

What power supplies produce direct current?

A

Cells and batteries

67
Q

Difference between AC voltage and DC voltage

A

In DC the voltage remains constant whereas in AC the voltage changes between positive and negative

68
Q

When resistors are connected in series the resistance (Increases/decreases) and why ?

A

Increases
because the sum of resistances of individual resistors is equal to the total resistance

69
Q

When resistors are connected in parallel the resistance (increases/decreases) and why?

A

Decreases
because the current has more pathways to go through therefore it’s easier for current to flow

70
Q

Frequency meaning

A

Number of cycles (number of times the current changes direction) each second

71
Q

Why do wires become hotter when an electric current passes through them?

A

As electrons flow through wires, they collide with the positive ions in the wire which causes the ions to vibrate more • This increased vibration of the ions increases the temperature and resistance of the wire • Energy has been transferred from kinetic energy into thermal energy

72
Q

Live wire

A

Copper wire coated with brown plastic • Carries alternating current at 230V

73
Q

Neutral wire

A

Copper wire coated with blue plastic • Completes the circuit and is at 0V

74
Q

Earth wire

A

Copper wire coated in green and yellow striped plastic • Used for safety and is at 0V

75
Q

Function of fuse

A

Prevents electrical circuits from excessive current • Melts if current gets too high

76
Q

What happens once the fuse melts?

A

The circuit is broken and no more current can flow through the device

77
Q

As I-V graphs curve what happens to resistance?

A

It increases

78
Q

Ways of reducing unwanted energy transfer through wires

A

Using thicker wires with a lower resistance to minimise heat produced

79
Q

A

Provides warmth for electric heaters and kettles

- Often a form of wasteful energy
- Can lead to overheating and potentially a fire

80
Q

How do LDRs increase in resistance?

A

When light intensity decreases

81
Q

What happens to the resistance of a thermistor as temperature increases?

A

It decreases

82
Q

What happens to the resistance of a filament lamp as temperature increases?

A

It increases

83
Q

Application of LDRs or Thermistors

A

Used in sensor circuits: eg thermostats which regulates the temperature in heating/cooling systems

84
Q

(SP8) GPE equation

A

GPE = mass (kg) x gravitational field strength (N/kg) x vertical height raised (m)

85
Q

Unlike charges (attract/repel)

A

Attract

86
Q

Like charges (attract/repel)

A

Repel

87
Q

The more friction that occurs…

A

The more electrons that flow

88
Q

How does an insulator become charged by friction?

A

When two insulating materials are rubbed together, electrons are transferred creating an imbalance of charge that’s built up

89
Q

Why do insulators not lose its charge?

A

Electrons can’t be conducted in an insulator

90
Q

Earthing

A

The removal of excess charge by the movement of electrons

91
Q

What happens during a spark?

A

The electrons jump between 2 charged objects creating a visible discharge of electricity

92
Q

Static electricity meaning

A

The build up of charge on insulators

93
Q

Objects normally have a neutral charge overall. Explain why.

A

Normally, the number of positive protons is equal to the number of negative electrons, so the charges balance each other making the overall charge is neutral.

94
Q

How does lightning occur?

A

• In a storm, clouds move over each other and causes them to become charged as electrons are transferred • The build up of negative charge in the clouds jump as it attracts to the positive charges on the ground • It creates a giant spark as the potential difference is large enough to overcome the resistance of the air

95
Q

Why can sparks be dangerous?

A

They can cause a fire by igniting flammable gases and liquids eg petrol

96
Q

Meaning of force

A

A push or pull acting on an object

97
Q

How does current compare in series and parallel circuits

A

Current is the same throughout a series circuit but splits in parallel

98
Q

How does voltage compare in series and parallel circuits?

A

Voltage is split across components in series but is the same throughout parallel circuits

99
Q

Electrical field

A

A region where an electric charge experiences a force

100
Q

Where are electrical fields weakest on a charged object

A

At the edges

101
Q

What direction do field lines go in positive and negative objects?

A

Positive : Outwards
Negative : Inwards

102
Q

How many watts is a MW?

A

1,000,000 W

103
Q

Charging by induction

A

When the magnetic field of a charged object induces a charge on a neutral object

104
Q

The closer together the arrows are in field lines…

A

The stronger the electric field

105
Q

Examples of items that become charged by friction

A

Polythene rod, cloth and balloons

106
Q

What subatomic particle is transferred to make an object charged?

A

Electrons, -e

107
Q

Why do materials that gain electrons become negatively charged?

A

Electrons are negatively charged particles and the imbalance of electrons creates an overall negative charge

108
Q

How do we experience shocks from everyday objects?

A

When we touch a charged object the excess charge flow through our bodies creating an electric shock

109
Q

How does earthing remove excess charge?

A

When objects are connected to the ground (through conductors) any excess charge will flow into the ground and neutralise the charge

110
Q

How do insecticide sprayers use static electricity?

A

• Insecticide is given a charge as it leaves the sprayer • The droplets then repel each other as they have the same charge • This helps it cover a large surface area

111
Q

Dangers of refuelling a vehicle

A

Flammable fuel runs through pipes at a fast rate • The friction between the fuel and the pipe causes the fuel to gain charge • Build up of charge may cause a spark and ignite the fuel creating an explosion

112
Q

How is sparking prevented during the refuelling of aeroplanes ?

A

A bonding line carries excess charge from the plane to the Earth to neutralise the charge • This is a form of earthing