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GCSEs > Physics (paper 1) 📍 > Flashcards

Physics (paper 1) 📍 Flashcards

1
Q

What are the function of waves?

A

They transfer energy and information without transferring matter

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2
Q

Wavelength (λ)

A

Minimum distance in which a wave repeats itself

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3
Q

What is a wavelength measured in?

A

Metres

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4
Q

Amplitude (A)

A

Distance between the origin and the crest/trough

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5
Q

Frequency (f)

A

Number of waves that pass a point in a second

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6
Q

Frequency and wavelength are

A

inversely proportional
• High frequency = short wavelengths
• Low frequency = long wavelengths

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7
Q

How is the wavelength measured in transverse and longitudinal waves?

A

Transverse waves:
From one peak/crest to the next

Longitudinal waves:
From the centre of one compression to the next centre of compression

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8
Q

Time period (T)

A

The time taken for a single wave to pass a point

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9
Q

Wave velocity (speed)

A

The distance travelled by a wave each second

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10
Q

Transverse wave

A

Waves where the particles move perpendicular to the direction of energy transfer (oscillating motion)

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11
Q

Examples of transverse waves

A

• Ripples on the surface of water
• S - waves
• Electromagnetic waves (eg radio, light, x rays)

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12
Q

Longitudinal wave

A

Wave where the particles vibrate parallel to the direction of energy transfer (side to side motion)

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13
Q

What type of wave can travel through a vacuum?

A

Electromagnetic waves

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14
Q

When the points are close together in a longitudinal wave

A

Compression

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15
Q

When the points are spaced apart in a longitudinal wave

A

Rarefaction

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16
Q

Examples of longitudinal waves

A

• Sound waves
• P - waves
• Ultrasound
• Infrasound

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17
Q

Equations for wave speed (m/s)

A

• v = x/t
(Wave speed = distance/time)

• v = f x λ
(Wave speed = frequency x wavelength)

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18
Q

How do you work out wavelength? (λ)

A

Length x 2

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19
Q

Seismic wave

A

Wave produced by earthquakes

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20
Q

Types of wave interactions through an interface

A

• Reflection
• Refraction
• Transmission
• Absorption

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21
Q

Materials interact differently with waves depending on the wave’s ______

A

wavelength

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22
Q

Reflection definition

A

The bouncing back of a wave at a boundary

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23
Q

Refraction definition

A

When a wave changes speed at the boundary between materials of different densities

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24
Q

Transmission definition

A

When a wave passes through a substance

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25
Q

Absorption definition

A

When energy is transferred from the wave to the particles of a substance

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26
Q

What’s an echo?

A

Sound waves being reflected off a surface

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27
Q

How do waves get reflected?
(effect)

A

• Flat surfaces are the most reflective
(The smoother the surface, the stronger the reflected wave)
• Light will reflect if the object is opaque
• Electrons absorb the light energy and re emit it as a reflected wave

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28
Q

What does it mean if an object appears yellow?

A

• Only yellow light has been reflected
• All other wavelengths of visible light have been absorbed

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29
Q

What happens when waves speed up?

A

• The frequency stays the same
• The wavelength increases (gets longer)
• The waves travel away from the normal

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30
Q

What happens when waves slow down?

A

• The frequency stays the same
• The wavelength decreases
• The waves travel toward the normal

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31
Q

What is a normal

A

A line drawn perpendicular to an interface

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32
Q

Sound waves definition

A

The vibrations of molecules

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33
Q

Regions of higher and lower density in a longitudinal wave

A

Higher density: Compression
Lower density: Rarefaction

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34
Q

Range of frequencies humans can hear

A

20 Hz to 20,000 Hz

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35
Q

Ultrasound

A

Sound waves with a frequency above the human hearing range of 20000 Hz

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36
Q

Infrasound

A

Sound waves with a frequency below the human hearing range of 20 Hz

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37
Q

Explain the way the human ear works

A

• Vibrations in the air travels down the auditory canal causing the eardrum to vibrate
• Vibrations are passed onto the three small bones
• These bones amplify vibrations and transmit them to the liquid in the cochlea
• Tiny hairs in the cochlea detect vibrations and create electrical impulses
• They travel along neurones in the auditory nerve to the brain

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38
Q

Incident angle

A

Angle of the entering ray

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39
Q

What is the angle of reflection?

A

The angle of the exiting ray

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40
Q

Can sound waves travel through a vacuum? Explain.

A

• No. Longitudinal waves rely on vibrating particles to travel
• In a vacuum there are no particles to vibrate, and so sound waves can’t be transmitted.

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41
Q

How is ultrasound used in sonar?

A

• Ultrasound is emitted from a boat and travels towards the sea bed
• Ultrasound reflects off the sea bed and is detected by the boat
• The time between emission and detection is recorded
• This can be used to find out the depth of seabed

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42
Q

Ultrasound uses

A

• Foetal scanning
• Sonar
• echo location

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43
Q

Infrasound uses

A

• Exploration of the Earth’s core
• Detecting seismic activity

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44
Q

How is ultrasound used for foetal scanning?

A

• A transducer produces and detects a beam of ultrasound waves in body
• Ultrasound waves are bounced back to the transducer by different boundaries
• The echo reaches the transducer causing it to generate electrical signals to send to the scanner
• The detector calculates the tissue’s distance from transducer using speed and time
• Time measurements are used to build up an image

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45
Q

Why is ultrasound a safe method for foetal scanning compared to eg X rays?

A

• x rays are ionising whereas ultrasound isn’t
• Therefore x rays could damage tissue and mutate cells

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46
Q

What is applied during foetal scanning and why?

A

Gel is applied to ensure ultrasound is absorbed not reflected off your body

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47
Q

How is infrasound used in the exploration of the earths core?

A

• Earthquakes produce P-waves and S-waves
• These pass through the Earth’s centre and can be detected using seismometers
• The location and magnitude can be identified after carefully timing the arrival of its waves

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48
Q

Characteristics of P-waves

A

Primary waves

• Longitudinal waves

• Faster than S-waves so are felt first during an earthquake

• Produce a forward and back motion

• Can pass through solids and liquids

• Are very low frequency sound waves (infrasound)

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49
Q

Characteristics of S-waves

A

Secondary waves

• Transverse waves

• Slower than P-waves so are felt after them during an earthquake

• Produces a side to side motion

• Can only travel through solids

• Unable to travel through the Earth’s molten outer core

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50
Q

Method to calculate wave speed by measuring the frequency

A

• Measure the frequency by counting the number of waves that pass a ping on the harbour each second

• Measure the wavelength by counting the number of waves between two point on the harbour and dividing the distance by the number of waves

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51
Q

[][Topic5][]
Concave meaning

A

Curving inwards

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52
Q

Convex meaning

A

Curving outwards

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53
Q

Focal length

A

The distance between the centre of the lens and the focal point

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54
Q

Real image

A

An image that is formed where the rays of light are focused and come together

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55
Q

Virtual image

A

An image where rays of light appear to come but don’t in reality

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56
Q

Incident ray

A

Light ray moving towards a boundary

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57
Q

Law of reflection

A

Angle of incidence is equal to the angle of reflection

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58
Q

Why might the angle of reflection have a range of values when being measured in a practical?

A

The light beam may have been wide

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59
Q

Properties of red light in terms of waves

A

• Has the longest wavelength
• Has the lowest frequency

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60
Q

Properties of violet light in terms of waves

A

• Has the shortest wavelength
• Has the highest frequency

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61
Q

White light is

A

a combination of all the wavelengths of light

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62
Q

Black is

A

the absence/ absorption of light

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63
Q

What colour would a blue object appear through a green filter and why?

A

• Black
• Blue light is being absorbed so no light is being transmitted making it appear black

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64
Q

What is the critical angle?

A

The angle of incidence that gives an angle of refraction of 90°

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65
Q

What is Total Internal Reflection?

A

• When all the light is reflected back into the denser medium
• No refraction occurs

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66
Q

Criteria for Total Internal Reflection to occur

A

• The rays of light must travel from a more dense to less dense medium

• The angle of incidence must be greater than the critical angle

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67
Q

If the angle of incidence is less than the critical angle…

A

The light ray is refracted (away from the normal)

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68
Q

If the angle of incidence is equal to the critical angle…

A

• The light ray is refracted at 90° to the normal
• Therefore it’ll travel along the surface of the denser medium

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69
Q

Converging lens is another name for

A

Convex lens

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70
Q

What do convex lens do to light?

A

They refract parallel rays of light inwards into a single point (aka focal point)

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71
Q

What do concave lens do to light?

A

They refract parallel rays outwards

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72
Q

The shorter the focal length…

A

The more powerful the lens are

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73
Q

How do you make a lens more powerful without changing the focal length?

A

Make the lens more curved

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74
Q

How is an image formed?

A

When all the light rays from a point on an object come together

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75
Q

Inverted images are always

A

Real

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76
Q

Virtual images are always

A

Upright

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77
Q

Convex lens can produce

A

Real or virtual images

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78
Q

Concave lens always produce

A

Virtual images

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79
Q

Magnification equation

A

Image height / Object height

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80
Q

What happens when a ray of light travels perpendicular to a boundary?

A

The direction doesn’t change since it’s travelling along the normal

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81
Q

What is the critical angle of glass?

A

42°

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82
Q

What do all electromagnetic (EM) waves have in common?

A

• They are transverse waves
• They travel at the speed of light

83
Q

What are the 7 waves on the EM spectrum?

A

• Radiowaves
• Microwaves
• Infra red rays
• Visible light waves
• Ultraviolet rays
• X-rays
• Gamma rays

84
Q

What EM wave has the longest wavelength?

A

Radiowaves

85
Q

What EM wave has the highest frequency and energy?

A

Gamma rays

86
Q

How are gamma rays produced?

A

By changes in the nucleus of an atom

87
Q

What are the 3 ionising EM waves?

A

• UV rays
• X-rays
• Gamma rays

88
Q

What is the impact of ionising waves?

A

They can damage/mutate cells and therefore cause cancer

89
Q

Uses of radiowaves

A

• Communications
• Satellite transmissions
• TV broadcasting

90
Q

Uses of microwaves

A

• Heating food
• Mobile phone and satellite communication

91
Q

Uses of infrared

A

• Remote control
• Night vision
• Electrical heaters
• Cooking

92
Q

Uses of visible light waves

A

• Helps us see
• Photography

93
Q

Uses of ultraviolet

A

• Fluorescent bulbs
• Getting a suntan

94
Q

Uses of x-rays

A

• Used to image luggage and broken bones

95
Q

Uses of gamma rays

A

• Sterilising medical equipment
• Treating cancer

96
Q

Danger of microwaves

A

They heat up cells

97
Q

Danger of infrared

A

It can cause skin burns

98
Q

Dangers of ultraviolet

A

• Causes damage to skin cells (leading to cancer like X-rays and gamma rays)
• Can cause blindness

99
Q

What is diffuse reflection?

A

• When light is reflected off a surface and is scattered in different directions
• Common in rough surfaces

100
Q

What is specular reflection?

A

• When light rays reflect at the same angle they hit the surface
• Common in smooth surfaces like mirrors

101
Q

Radiowaves can be created using what type of current?

A

Alternating current

102
Q

What is an oscilloscope?

A

• A device that allows us to see the frequency of the alternating current
• This helps us determine the frequency of the radio wave

103
Q

What would happen to an object if it emits more energy than it absorbs?

A

It would lose energy and cool down

104
Q

What would happen if an object emits and absorbs the same amount of energy?

A

It would stay the same temperature

105
Q

Intensity meaning

A

The power of radiation per unit area

106
Q

What type of EM waves are included in a diagram of emitted radiation?

A

• UV radiation
• Visible light
• Infrared radiation
(in order of increasing wavelength)

107
Q

What effect does the temperature of an object have on intensity?

A

• As the temperature increases, the intensity of every emitted wavelength increases
• With the shorter wavelengths increasing at a higher rate

108
Q

Why does the colour of a Bunsen burner flame change as it gets hotter?

A

• The hotter the flame, the shorter the wavelength of light emitted
• Colour changes from orange to blue

109
Q

What is the emitted radiation for an object at room temperature?

A

• Infra red radiation
• Not also visible light because we can’t see the emitted radiation

110
Q

First atom model

A

• Dalton’s billiard ball model
• Tiny sphere that couldn’t be broken up

111
Q

What atom model did JJ Thompson propose?

A

• The plum pudding model
• A dough of positive charge with negative electrons in it

112
Q

What atom model did Rutherford propose?

A

• Nuclear model
• Positively charged nucleus surrounded by a cloud of negative electrons

113
Q

What atom model did Bohr propose?

A

• The Bohr model
• Electrons orbit the nucleus at fixed distances called energy levels or shells

114
Q

[] What is the equation for calculating speed?

A

• v (m/s) = x (m) / t (s)
• Average speed = total distance / time taken

115
Q

Equation for calculating acceleration

A

• a (m/s²) = /\ v (m/s) / t (s)

• a = v - u
———
t

• change in velocity / time taken
• final velocity - initial / time

116
Q

Equation for calculating uniform (constant) acceleration

A

• a = v² - u² / 2x
• (final speed)² - (initial speed)² / 2 x distance travelled

117
Q

When the resultant force is 0N, what does it indicate about an object?

A

The object is either moving at constant speed or is stationary

118
Q

Newton’s first law for a stationary object

A

If the resultant force on a stationary object is zero, the object will remain at rest

119
Q

Newton’s first law for a moving object

A

If the resultant force on a moving object is zero, the object will remain at constant velocity (same speed in same direction)

120
Q

What is the equation for force?

A

Mass x Acceleration

121
Q

Newton’s second law of motion

A

The acceleration of an object is directly proportional to the net force and inversely proportional to its mass (f= ma)

122
Q

Weight meaning

A

Force acting on an object due to gravitational attraction

123
Q

Newton’s third law

A

Whenever two bodies interact, the force they exert on each other are equal and opposite

124
Q

How do you calculate momentum?

A

Mass x Velocity
p (kg m/s) = m (kg) v (m/s)
(p = mv)

125
Q

Conservation of momentum

A

Total momentum before a collision = total momentum after a collision

126
Q

Other ways of calculating force

A

(mv - mu) / t
=
(m △v) / t
=
△p /t

127
Q

Is momentum a scalar or vector quantity?

A

Vector

128
Q

How is momentum conserved in a collision?

A

• P = mv
• The forces exerted by both objects are equal and opposite (3rd law)
• Force of X on Y = -force of Y on X
• So change in momentum of X = -change in momentum of Y
• Y accelerates because of force from X
• So total momentum before collision = total momentum after collision

129
Q

When does the momentum of an object change?

A

• If an object accelerates / decelerates
• If it changes direction
• If its mass changes

130
Q

Equation for weight

A

W = mg
(mass x gravitational field strength)

131
Q

Closed system meaning

A

When the energy within an object/ objects is constant and there is absence of external forces (eg friction)

132
Q

Force definition

A

Rate of the change in momentum
• /\ p / /\ t
• (change in momentum / change in time)

133
Q

Stopping distance meaning

A

The total distance travelled during the time it takes for a car to stop in response to emergency

134
Q

Equation for stopping distance

A

SD = Thinking distance + Braking distance

135
Q

Thinking distance meaning

A

The distance travelled during the driver’s reaction time
(in metres)

136
Q

Braking distance meaning

A

The distance travelled under the braking force
(metres)

137
Q

Factors that affect thinking distance

A

• Tiredness
• Excessive drug/ alcohol intake
• Poor visibility
• Speed

138
Q

Factors that affect braking distance

A

• Icy/wet roads
• Speed
• Mass of car
• Condition of tyres/brakes

139
Q

Equations for braking distance

A

• Ek / f
• = 1/2mv² /ma

140
Q

How is energy transferred as a car brakes?

A

Energy is transferred from kinetic energy to sound and thermal energy

141
Q

Work done by brakes is equal to

A

The kinetic energy of the car

142
Q

Equation that shows that the work done is the transfer of kinetic energy

A

Braking force x Braking distance = 1/2 x mass x velocity² (kinetic force)

143
Q

In elastic collisions, what happens to kinetic energy?

A

Kinetic energy is conserved

144
Q

In inelastic collisions, what happens to kinetic energy?

A

Kinetic energy changes (usually decreases)

145
Q

Why does an object accelerate during circular motion?

A

• The direction of the object is constantly changing
• Therefore the velocity is changing as it’s a vector
• Because acceleration is the rate of change of velocity it would also change

146
Q

What does M mean eg in or MHz or MW?

A

• Mega
• 10^6

147
Q

What does G mean eg in GHz or GW?

A

• Giga
• 10^9

148
Q

Centripetal force meaning

A

The perpendicular force acting towards the circle’s centre that keeps an object in uniform circular motion

149
Q

What factors affect the size of a centripetal force?

A

• Mass
• Acceleration

150
Q

Typical walking speed

A

1.5 m/s

151
Q

Typical running speed

A

3 m/s

152
Q

Typical cycling speed

A

6 m/s

153
Q

Speed of sound

A

330 m/s

154
Q

Typical person’s reaction time

A

0.2s - 0.9s

155
Q

Describe Rutherford’s Alpha Particle Experiment

A

• A beam of alpha particles (He 2+ ions) was directed at a thin gold foil

• He discovered that:
• Most of the particles passed straight through the metal (showing atoms are mostly empty space)

• Some alpha particles were deflected as they repelled (showing how the nucleus of atoms have strong positive charge)

• Very few of the particles bounced back (showing that atoms contain a small, heavy nucleus)

156
Q

What conditions were required for Rutherford’s experiment?

A

• Thin gold foil was used rather than thick
• So particles were able to pass through it

• The chamber was evacuated
• The air was removed so none of the alpha particles would collide with anything before reaching the foil

157
Q

What is radioactivity?

A

When an unstable nucleus loses energy as it emits radiation

158
Q

What are the 3 types of radiation?

A

• Alpha particles
• Beta particles
• Gamma radiation

159
Q

Ionising radiation meaning

A

• When radiation has enough energy to remove an electron from the shell of an atom
• Dangerous as it causes DNA damage and cancer

160
Q

How do we measure/detect radiation?

A

• We use a GM tube (Geiger Muller) and counter
• We place the source in front of the GM tube and every time it clicks it measures the number of radiations per second

161
Q

Radiation meaning

A

The giving off of excess energy

162
Q

Unit for radiation

A

Becquerel (Bq)

163
Q

Alpha particles characteristics

A

• 2+ charge (Helium nucleus)
• Mass of 4 (2 protons and neutrons)
• Stopped by skin or a sheet of paper
• Most ionising power
• Only travels a few cm

164
Q

Beta particle characteristics

A

• Charge of -1
• (fast moving electron)
• Mass of 0
• Stopped by a sheet of aluminium
• Moderate ionising power
• Can travel up to a metre

165
Q

Gamma radiation characteristics

A

• Type of wave
• Charge and mass of 0
• Stopped by thick sheets of lead/concrete
• Weak ionising power
• Most penetrating
• Can travel long distances
• Travels at speed of light

166
Q

Irradiation meaning

A

When someone is exposed to ionising radiation but doesn’t come into contact with it

167
Q

Contamination meaning

A

When someone comes into contact with radioactive isotopes

168
Q

Protective measures to reduce exposure to sources

A

• Long tongs to handle source
• Lead aprons/ protective masks
• Stand behind barriers
• Personal radiation monitor

169
Q

Background radiation

A

Exposure to ionising radiation at low levels form naturally radioactive substances

170
Q

Sources of background radiation

A

• Radon gas from rocks (50%) (trapped in earth)
• Cosmic rays
• Gamma rays from ground and buildings

171
Q

Approximate size of an atom

A

1 x 10^-10 m

172
Q

What is alpha radiation used for?

A

• Fire alarms
• Alpha source in fire alarm causes ionisation and current
• Smoke particles stop the current causing the alarm to sound

173
Q

What is beta radiation used for?

A

• Thickness control for paper/aluminium as they partially absorb it
• If the amount of detected radiation changes, thickness has changed so rollers are adjusted

174
Q

What is gamma radiation used for?

A

• Detecting leaks in underground pipes
• Sterilise medical equipment as it kills microbes
• Detecting cancer

175
Q

Radioactive decay is…

A

random

176
Q

Equation linking acceleration, distance and velocity

A

v² - u² = 2ax

177
Q

Nanometres to metres

A

1 x 10 ^ -9

178
Q

Possible reasons to why there are limits to the frequencies the human ear can detect

A

• Eardrum not sensitive enough to detect low/high frequencies
• Brain cannot interpret low/high frequencies

179
Q

What happens in a nuclear decay?

A

The mass (nucleon) number, atomic number and charge is conserved

180
Q

What happens in an alpha/beta decay?

A

The nucleus transmutes into another element and both the atomic & mass number changes

181
Q

What takes place during beta - decay?

A

• A neutron in the nucleus of an atom turns into a proton and electron
• The electron leaves the nucleus
• The atomic number increases by 1 as there’s one more protein

182
Q

What takes place during beta + decay?

A

• A proton in the nucleus turns into a neutron and positron
• The positron leaves the nucleus
• The atomic number decreases by 1 as there’s one less proton than before

183
Q

Equation for beta - decay

A

1 1 0
n —-> p + β
0 1 -1

184
Q

Equation for beta + decay

A

1 1 0
p —-> n + β
1 0 +1

185
Q

Half-life definition

A

The time it takes for half of the radioactive nuclei in a source to decay

186
Q

Formula for activity rate

A

A = Ao (original activity)
——-
2^n (number of half lives)

187
Q

What happens during gamma radiation?

A

• Gamma is a wave that carries energy away from the nucleus
• Therefore proton and mass number stay the same

188
Q

Medical tracer meaning

A

A radioactive isotope that can be used to track the movement of substances in the body eg blood

189
Q

Why are gamma emitters used as a tracer?

A

• They’re highly penetrating and are able to pass through body whilst still being detected outside body
• They have low ionising levels so any harm to the patient is minimal

190
Q

Why is it beneficial for isotopes to have short half lives when being used as a tracer?

A

• So its unlikely to cause long term damage to the patient
• Whilst still being able to take an image before radioactivity decreases

191
Q

What is PET (Positron Emission Tomography)?

A

• Positrons are emitted as the tracer decays
• They travel a small distance and annihilate (get converted) when they interact with electrons in the tissue
• A pair of gamma rays are produced and can be detected outside the body

192
Q

Nuclear fission meaning

A

The splitting of a large, unstable nucleus into 2 smaller nuclei (usually uranium-235)

193
Q

What happens during nuclear fission?

A

• A slow moving neutron is fired at a nucleus
• The nucleus absorbs the neutron and becomes unstable
• The nucleus splits into 2 smaller (daughter) nuclei
• 2/3 rapid neutrons and a lot of energy are released

194
Q

Purpose of nuclear reactor

A

• Converts energy from nuclear fission into electricity
• They produce energy at the correct rate if the number of neutrons in the reactor is constant

195
Q

How does chain reactions occur?

A

• The new neutrons from previous fission can be absorbed by another nucleus and start another fission reaction which creates excess neutrons

196
Q

Purpose of chain reactions

A

They keep nuclear reactors running

197
Q

Purpose of control rods in nuclear reactor

A

• Control chain reactions
• They absorb neutrons without becoming unstable themselves
• Made of boron material

198
Q

Purpose of moderator in nuclear reactors

A

• Slow neutrons produced by fission down to maintain chain reaction
• Made of water/graphite

199
Q

Nuclear fusion meaning

A

When 2 light nuclei join to form a heavier

200
Q

Nuclear fusion characteristics

A

• Light nuclei are both positively charged so they repel
• Requires extremely high temperatures to overcome repulsion
• Stars use nuclear fusion to produce energy

201
Q

Comparing nuclear fusion and nuclear fission

A

• Both produce large amounts of energy
• Nuclear fission requires a neutron

202
Q

Why does light intensity decrease as it travels between different boundaries?

A

Light is always reflected when it passes through a boundary so some energy gets lost

203
Q

Practical for measuring the critical angle using a semi circular glass

A

• Shine a ray of light into the block through curved face
• Change angle until angle of refraction = 90°
• Measure angle of incidence when refracted angle is 90° using a protractor
• Repeat measurement of critical angle

204
Q

Comparing radiowaves and gamma rays

A

• Radiowaves are created by oscillations of moving electrons
• Are produced by humans
• Are produced in electrical currents

• Gamma rays may result from radioactive decay
• Gamma rays are produced to stabilise nucleus
• Produced by annihilation in PET

GCSEs (21 decks)

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