100 or so IGCSE Physics things to learn Flashcards

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1
Q

Why do different planets have different values of g (gravitational field strength)

A

Planets with more mass (e.g. Jupiter) have a higher value of g

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2
Q

What is felt when a current-carrying wire is in a magnetic field?

A

A force is felt when a wire carries a current in a magnetic field

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3
Q

What happens to the resistance of a thermistor as it is heated

A

High temperatures reduces the resistance of a thermistor

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4
Q

Give the unit and unit symbol for

Power, P

A

watt (W)

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5
Q

Give the unit and unit symbol for

Density, ρ

A

kilogram per metre cubed (kg/m3)

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6
Q

What component is this?

A

Bulb

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7
Q

What does work done = energy transferred mean?

A

If you do 10J of work on a system you transfer 10J of energy to it.

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8
Q

What materials does conduction happen best in and why?

A

Solids; particles are close together so can pass energy quickly. Works best of all in metals due to free electrons.

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9
Q

What equation links;

weight, mass and gravitational field strength

A

weight = mass x gravitational field strength

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10
Q

How would you find the volume of a small irregular object (e.g. a pebble)

A

submerge in water. The volume of water displaced = volume of pebble

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11
Q

How does a fuse work

A

When the current goes higher than the value of the fuse it melts. This breaks the circuit and stops current flowing

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12
Q

Give a use for x-rays

A

looking at the insides of things (medical imaging and other objects)

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13
Q

Give the unit and unit symbol for

Acceleration, a

A

metre per second squared (m/s/s, m/s2)

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14
Q

How would you find the volume of a regular object (e.g. a cube of metal)

A

measure each side (with ruler) and multiply together

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15
Q

What equation links;

pressure, force and area

A

pressure = force ÷ area

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16
Q

When a gas or liquid is at rest, what can you say about the pressure?

A

at a given depth, pressure in a fluid at rest acts equally in all directions

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17
Q

Describe a longitudinal wave and give an example

A

Longitudinal waves travel parallel to the oscillation which caused them. E.g. sound

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18
Q

Give a use for radio

A

Communictions and broadcast

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19
Q

What are the energy transfers involved with nuclear power

A

nuclear ⇒ thermal ⇒ kinetic ⇒ electrical

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20
Q

Give a danger and use for microwaves

A

Danger = internal heating of body tissue,

Use = cooking and satellite communications

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21
Q

What equation links;

charge, current and time

A

charge = current x time

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22
Q

Give a danger and use for ultra violet

A

Danger = blindness and damage to surface cells,

Use = flourescent lamps, security markings

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23
Q

What is a magnetic field line?

A

A magnetic field line shows the direction of a magnetic field (N to S). Where lines are close together the field is strong.

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24
Q

What happens to the current in a circuit when the resistance is decreased?

A

Current increases as resistance decreases

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25
Q

The gradient of a velocity-time graph gives

A

Acceleration

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26
Q

The gradient of a distance-time graph gives

A

Speed

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27
Q

Explain series circuits

A

Only one loop, simple, if one component fails no current flows

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28
Q

What equation links;

refractive index, angle of incidence, angle or refraction

A

n = sin i ÷ sin r

refractive index = sin (angle of incidence) ÷ sin (angle of refraction)

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29
Q

The universe is made up of….

A

Billions of galaxies

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30
Q

What equation links;

acceleration, change in velocity and time taken

A

acceleration = change in velocity ÷ time taken

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31
Q

Define the time period of a wave

A

Time period is how long it takes for a wave to pass a point

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32
Q

What equation links;

work done, force and distance moved

A

work done = force x distance moved

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33
Q

What is the order of the EM spectrum

A

Radio, Microwave, Infra-red, Visible, Ultra-violet, X-ray & Gamma

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34
Q

When a wave is refracted what two things change

A

Speed and direction change during refraction

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35
Q

What is the difference between Alternating Current (AC) and Direct Current (DC)

A

DC (direct current) only flows in one direction. AC (alternating current) constantly changes direction.

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36
Q

What equation links;

moment, force and perpendicular distance from pivot

A

moment = force x perpendicular distance from pivot

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37
Q

Give the unit and unit symbol for

Charge, Q

A

coulomb (C)

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38
Q

What materials does convection happen best in and why

A

Fluids (gases and liquids); particles must be free to move so can’t happen in a solid

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39
Q

Give the unit and unit symbol for

Potential Difference, V

A

volt (V)

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40
Q

What component is this?

A

Thermistor

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41
Q

What is the force which opposes motion

A

Friction (e.g. against a road) or drag (e.g. moving through air)

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42
Q

Give the unit and unit symbol for

Wavelength, λ

A

metre (m)

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43
Q

Factors which affect braking distance

A

Speed, weight of vehicle, quality of brakes and tryes, road surface

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44
Q

Give the unit and unit symbol for

Pressure, p

A

pascal, newton per metre (Pa, N/m2)

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45
Q

What equation links;

wave speed, frequency and wave length

A

wave speed = frequency x wave length

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46
Q

What are the energy transfers involved with water power

A

gravitational ⇒ kinetic ⇒ electric

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47
Q

Describe a transverse wave and give an example

A

Transverse waves travel at right angles to the oscillation which caused them. E.g. light, other EM waves, Mexican Waves

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48
Q

What are circuit breakers

A

Circuit breakers break the circuit when the current goes higher than a certain value. Unlike fuses, they can be reset once tripped.

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49
Q

How does convection produce wind?

A

Air is heated, expands, becomes less dense, rises, colder air rushes into the area of low pressure.

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50
Q

What is the relationship between force and extension for a spring

A

Force is directly proportional to extention (if force doubles extension doubles)

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51
Q

What do the thumb and fingers represent when using Flemming’s Left Hand Rule?

A

thumb = force (direction of movement),

First Finger = Field,

seCond finger = Current

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52
Q

What makes something an elastic material

A

Material regains original shape once stretching force is removed

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53
Q

When the angle of incidence is less than the critical angle light is…

A

When the angle is less than the critical angle, light is refracted

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54
Q

Describe how thermal energy is transferred by radiation

A

Thermal radiation is an electromagnetic wave.

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55
Q

What is the frequency range for human hearing

A

20 Hz - 20 000 Hz

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56
Q

The initial linear part of a force-extension graph is linked to what law?

A

Hooke’s Law (Force is directly proportional to extension)

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57
Q

Our local galaxy is called

A

The Milky Way

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58
Q

What component is this?

A

LDR (light dependent resistor)

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59
Q

When the angle of incidence is greater than the critical angle light is…

A

Totally internally reflected

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60
Q

What happens when current flows through a resistor

A

When current flows through a resistor it heats up (this effect is used in kettles and toasters etc.)

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61
Q

What materials does radiation happen best in and why?

A

Transparent (see through) materials; thermal radiation can be absorbed by some materials and pass through others.

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62
Q

Why does an object reach terminal velocity?

A

As the speed and drag increase, eventually weight = drag so no resultant force

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63
Q

Natural satellites (e.g. moons) and artificial satellites (e.g. Hubble) orbit what?

A

Planets

64
Q

What equation links;

energy transferred and work done

A

energy transferred = work done

65
Q

Factors which affect thinking distance

A

Speed, awareness (tired, alcohol)

66
Q

What are the energy transfers involved with fossil fuels

A

chemical ⇒ thermal ⇒ kinetic ⇒ electrical

67
Q

Give the unit and unit symbol for

Area, A

A

metre squared (m2)

68
Q

Only appliances with what sort of case need an Earth wire?

A

Appliances with metal cases; if the live wire comes loose someone could get a shock without an Earth wire.

69
Q

What equation links;

gravitational potential energy, mass, g and height

A

gravitational potential energy = mass x g x height

70
Q

What is the principle of conservation of energy

A

Energy cannot be created or destroyed; only changed from one form to another.

71
Q

Where does the ray go next in each case?

A
72
Q

Give the unit and unit symbol for

Electric current, I

A

amp (A)

73
Q

A galaxy is made up of…

A

Billions of stars

74
Q

How would you describe a uniform field (3 marks)

A

Field lines are straight, parallel and equally spaced in a uniform field

75
Q

Define frequency

A

Frequency is the number of waves going past a point per second

76
Q

List the 5 types of non stored energies

A

Light, sound, thermal, kinetic, electrical

77
Q

If a car has 20 000J of kinetic energy, how much work do the brakes have to do to stop the car?

A

20 000J

78
Q

What is double insulation

A

Appliances with plastic cases are double insulated; even if live wire comes loose inside, a user can’t be shocked

79
Q

What component is this?

A

Diode

80
Q

What happens to the current in series circuit as more bulbs are added?

A

More bulbs in series increases the resistance and decreases the current

81
Q

What are the energy transfers involved with solar cells

A

light ⇒ electrical

82
Q

The area under a velocity-time graph gives

A

Distance travelled

83
Q

What part of the EM spectrum has the highest frequency (and energy)

A

Gamma has the highest frequency

84
Q

What happens to the speed of an object as it falls?

What happens to its drag?

A

Speed increases (resultant force downwards)

drag increases

85
Q

What are the energy transfers involved with solar heating systems

A

thermal ⇒ themal

86
Q

Describe how thermal energy is transferred by conduction

A

Particles knock into each other and pass on the energy

87
Q

If an object has 100J of gravitational potential energy when on a shelf and falls off, how much kinetic energy does it have just before hitting the floor? What have you assumed?

A

100J. But we assume there is no air resistance (100% efficient)

88
Q

How can you see the shape and direction of a magnetic field

A

Use plotting compasses

89
Q

What equation links;

refractive index and critical angle

A

n = 1 ÷ sin c

refractive index = 1 ÷ sin (critical angle)

90
Q

Refraction is when a wave………………………..

A

…bends

91
Q

Name some electrical conductors (low resistance, allow current to easily flow)

A

Metal, graphite

92
Q

Comets orbit what? What shapes are their orbits?

A

Comets orbit stars (e.g. the Sun) in elliptical orbits

93
Q

What part of the EM spectrum has the longest wavelength

A

Radio has the longest wavelength

94
Q

What is the law of reflection?

A

Angle of incidence = Angle of reflection

95
Q

Define wavelength

A

Wavelength is the distance between two peaks or two troughs

96
Q

Give the unit and unit symbol for

Moment

A

newton metre (Nm)

97
Q

How can you increase the speed of a motor (or volume of a speaker)?

A

Stronger magnet, more current

98
Q

Give an example of an AC source and a DC source

A

Mains are an AC source. Batteries are DC sources

99
Q

The rate of doing work is also known as?

A

Power

100
Q

How do radiators in your house heat a room (hint, not by radiation)

A

Radiators heat air which rises and produces a convection current. Cold air is drawn into the bottom of the radiator too.

101
Q

What is produced around a conductor when electrical current flows?

A

An electromagentic field is created when current flows

102
Q

What equation links;

efficiency, useful energy output and total energy input

A

efficiency = useful energy output ÷ total energy input

(also efficiency = useful energy output ÷ total energy output)

103
Q

Give the unit and unit symbol for

Frequency, f

A

hertz (Hz)

104
Q

Describe how thermal energy is transferred by convection

A

Hotter regions of fluid expand, become less dense and float on colder regions

105
Q

Give the unit and unit symbol for

Length, l

A

metre (m)

106
Q

Where does an objects weight always act

A

Through its centre of gravity

107
Q

List the 4 types of stored (potential) energies

A

Gravitational, Elastic, Nuclear, Chemical

108
Q

Why is the image in a mirror virtual?

A

The image in a mirror can’t be projected onto a screen

109
Q

What is the nature of an electric current in a metal conductor?

A

A flow of negatively charged electrons flowing from the negative side of a battery or power supply

110
Q

What happens to the resistance of an LDR as more light is shone on it?

A

Bright light reduces the resistance of an LDR

111
Q

Name some electrical insulators (high resistance, do not allow current to flow)

A

Plastic, wood, (pure) water

112
Q

What equation links;

force, mass and acceleration

A

force = mass x acceleration

113
Q

Which way does light bend when it enters a material with a higher refractive index (e.g. air to glass)

A

Light bends towards the normal when it goes from air to glass

114
Q

What equation links;

density, mass and volume

A

density = mass ÷ volume

115
Q

What is the critical angle

A

When ligh hits the boundary at the critical angle the angle of refraction is 90°

116
Q

Forces can do what to an object?

A

Change speed, shape or direction

117
Q

What is the efficiency of this machine

A

useful output energy = 10J

total input energy = 100J

efficiency = 10/100

= 0.1 or 10%

118
Q

How can you prevent heat transfer by radiation?

A

Shiny surfaces are poor emitters. They also refelect the thermal radiation back.

119
Q

Define amplitude

A

Amplitude is the maximum displacement above the equilibrium

120
Q

Give the unit and unit symbol for

Energy, E

A

joule (J)

121
Q

Give the unit and unit symbol for

Resistance, R

A

ohm (Ω)

122
Q

What are the energy transfers involved with wind power

A

kinetic ⇒ electric

123
Q

Planets orbit what? What shape are their orbits?

A

Planets orbit stars (e.g. the Sun) in circular orbits

124
Q

One Watt is equal to what?

A

1 watt is 1 joule per second

125
Q

What happens to the average speed of gas molecules as you heat a gas?

A

Average speed of gas molecules increases as you heat a gas

126
Q

What equation links;

pressure difference, height, density and g

A

pressure difference = height x density x g

127
Q

Reflection is when a wave…………………………

A

…bounces off something

128
Q

Electrical hazards include….

A

Frayed cables, damaged sockets, water near sockets and metal objects in sockets

129
Q

Give a danger and use for infra red

A

Danger = skin burns,

Use = cooking and night vision equipment

130
Q

Give the unit and unit symbol for

Time, t

A

second (s)

131
Q

Give the unit and unit symbol for

Volume, V

A

metre cubed (m3)

132
Q

What are meters X and Y?

A

X is a voltmeter (in parallel)

Y is an ammeter (in series)

133
Q

What equation links;

voltage, current and resistance

A

voltage = current x resistance

134
Q

What equation links;

kinetic energy, mass and speed

A

kinetic energy = 1/2 x mass x speed2

135
Q

Give a danger and use for gamma

A

Danger = cancer, mutation,

Use = sterilising food and medical equipment

136
Q

How can you show current is flowing in a circuit

A

A bulb or LED will light when a current flows. Or use an ammeter (in series)

137
Q

How can you visualise the shape of a magnetic field (3 marks)

A

Place magnet under paper, sprinkle iron filings on top of paper, gently tap paper so filings line up with field lines.

138
Q

What are the energy transfers involved with geothermal power

A

(nuclear) ⇒ thermal ⇒ kinetic ⇒ electric

139
Q

How can you prevent heat transfer by convection?

A

Trap the fluids (e.g. trapping air in wool). This prevents both conduction and convection.

140
Q

What component is this?

A

Wire

141
Q

How can you produce a uniform magnetic field (3 marks)

A

Place two attracting bar magnet poles (N&S) close together, hold them in place to avoid them touching

142
Q

Give the unit and unit symbol for

Force, F

A

newton (N)

143
Q

What component is this?

A

Diode

144
Q

Explain parallel circuits

A

Several routes for current to take, allows components to be switched on individually (e.g. lights at home), components get full supply voltage

145
Q

What is another name for the rate of flow of charge?

A

Current

146
Q

Why aren’t machines 100% efficient?

A

Typically some energy is lost to the surroundings as heat.

147
Q

Give the unit and unit symbol for

Velocity (initial, final), (u,v)

A

metre per second (m/s)

148
Q

Give the unit and unit symbol for

Temperature, T

A

kelvin (K)

149
Q

What is the easiest way to reduce risk of injury from microwaves, infra red, ultra violet or gamma

A

Avoid exposure

150
Q

Give the unit and unit symbol for

Mass, m

A

kilogram (kg)

151
Q

Give a use for visible light

A

Seeing, optical fibres, photography

152
Q

What component is this?

A

Variable resistor

153
Q

What equation links;

average speed, distance and time

A

speed = distance ÷ time

average speed = total distance ÷ total time

154
Q

How can you prevent heat transfer by conduction?

A

Use insulators (such as air)

155
Q

Waves transfer ……………………………… without transferring ……………………….

A

Waves transfer energy and information without transferring matter