Topic 4 - EM Radioton, EM Spectrum, Light, Reflection & Refraction

Question 1

From a graph, a student concludes that angle Y is directly proportional to angle X.
Explain what the student must do to test this conclusion in more detail. (3)

Answer 1

Repeat (1)
Different angles/more values of X (1)
For larger angles/values of X (1)

Question 2

Describe how a student could use a semicircular glass block and other apparatus to
determine the critical angle for a glass-air boundary. (4)

Answer 2

Shine a ray of light into the block (1)
Into the block through the curved surface along a radius (1)
Change angle until the angle of refraction is 90’ (1)
Measure angle of incidence when the angle of refraction is 90’ (1)
Repeat measurement of critical angle (1)

Question 3

Ultraviolet waves cover a range of frequencies.
Scientists divide this range into 3 types, UVA, UVB and UVC.
Figure 15 is a diagram about the effect that the Earth’s atmosphere has on 3 types of ultraviolet radiation.

UVA = transmitted + absorbed
UVB = transmitted + absorbed
UVC = reflected + absorbed
Describe how the effects change with wavelength. (4)

Answer 3

UVA mostly transmitted/some absorbed (1)
UVB some transmitted/mostly absorbed (1)
UVC not transmitted/mostly absorbed/some reflected (1)

Question 4

Describe an investigation to find out how the nature of a surface affects the amount of
thermal energy absorbed by the surface.
You should use: small infrared heating lamp and set of 3 cans of the same size & material but of different surfaces, and any additional items you choose.
Each can has a bung in the top with a hole in it. (6)

Answer 4

• uses a thermometer
• inserted into the can
• uses a stopwatch/timer
• uses a measuring cylinder/beaker with markings
• sets up apparatus with lamp a fixed distance from each can
• that distance is the same for each can
• the measured volume is the same for each can
• a starting temperature is measured
• (aiming) to get the same start temperature
• each, in turn, is heated for the same time
• as measured on a stopwatch
• a final (maximum) temperature is read
• OR takes a series of temperature readings with time
• and plots a graph of temperature(s) against time
• the one heating up the most is the best absorber

Question 5

White light includes all the colours in the visible spectrum.
A beam of white light is the only light that shines on a book.
The book appears green.
A red filter is placed between the source of white light and the book.
What colour does the book appear now? (1)

Answer 5

Black

Question 6

Which colour of visible light has the longest wavelength? (1)

Answer 6

Red

Question 7

Ultraviolet light has a higher frequency than infrared light.
Which of these colours of visible light has the highest frequency? (1)

A blue
B green
C orange
D yellow

Answer 7

Blue

Question 8

A student investigates how different surfaces radiate energy as they cool.
The student uses a copper container and hot water.
Describe how the student could collect data to show how the rate of cooling of the container
and water change with time. (2)

Answer 8

Use a thermometer (1)
Measure temperature at regular intervals (1)

Question 9

Give one colour of light that has a longer wavelength than yellow light. (1)

Give one colour of light that has a higher frequency than yellow light. (1)

Answer 9

Red/orange (1)
Blue/indigo/violet/green (1)

Question 10

Radio waves and gamma radiation are at opposite ends of the electromagnetic spectrum.
Compare how these two electromagnetic radiations are produced. (6)

Answer 10

• radio waves are (often) produced intentionally (by humans)
• gamma rays are (often) produced spontaneously / randomly
• radio waves are produced by (free) electrons
• radio waves are produced by oscillating (free) electrons / alternating current (ac)
• radio waves are produced in electrical circuits / aerials
• gamma rays may result from radioactive decay
• gamma rays produced in the nucleus
• gamma rays produced by energy changes / rearrangement in the nucleus
• gamma rays produced to stabilise the nucleus • gamma rays produced in annihilations (PET scanning
etc
• gamma rays may be produced as a result of (nuclear) fission or fusion

Question 11

Which EM wave matches the wave uses. (3)

To detect forged banknotes
To detect broken bones
For night vision cameras
To sterilise medical equipment

Answer 11

To detect forged banknotes - UV waves
To detect broken bones - X-ray waves
For night vision cameras - infrared waves
To sterilise medical equipment - gamma rays
(3)

Question 12

A person warms their hands in front of a hot fire (2)
The electromagnetic waves that the fire mostly emits are ……………………. waves.
These waves transfer …………………. energy to the hands.

Answer 12

Infrared (1)
Thermal (1)

Question 13

Some television remote controls use infrared radiation and other remote controls use radio
waves.
Explain why an infrared remote control may not switch on the television from behind an armchair but a radio wave remote control always will. (2)

Answer 13

Infrared is absorbed by the armchair/radio waves can go through the armchair (1)
Infrared and radio waves have different wavelengths frequencies (1)

Question 14

Which EM wave is: (1)
used in cooking
used in short-range communication
typical wavelength 900 nm

Answer 14

Infrared

Question 15

Which EM wave is: (1)
used in cooking
used in communication
typical wavelength 150 mm

Answer 15

Microwave

Question 16

Which EM wave is: (1)
used in communication
produced by oscillations in electrical circuits
typical wavelength 150 m

Answer 16

Radio wave

Question 17

Which EM wave is: (1)
used in medical scanning
is emitted by the nucleus of an atom
typical wavelength 2.0 × 10−3 nm

Answer 17

Gamma ray

Question 18

Name all the waves in the EM spectrum in order (1)

Answer 18

Gamma rays
X-rays
UV rays
Visible light
IR waves
Micro-waves
Radio waves

Question 19

All electromagnetic waves can travel in a vacuum.
Which of these is the same for all electromagnetic waves travelling in a vacuum? (1)
A amplitude
B frequency
C speed
D wavelength

Answer 19

Speed

Question 20

Some sunglasses have photochromic lenses.
Photochromic lenses are clear when the lenses are indoors but they darken in bright sunlight to reduce the effects of the sunlight.
Photochromic lenses react to ultraviolet light.
Suggest a benefit of making the lenses go dark with ultraviolet light. (1)

Answer 20

UV is the most harmful to the eyes (1)
Protects eyes from damage from UV rays (1)

Question 21

State one type of electromagnetic radiation that has a higher frequency than ultraviolet. (1)

Answer 21

X-rays (1)
Gamma rays (1)

Question 22

One star is blue and another star is red.
Explain why an astronomer expects the blue star to be hotter than the red star. (2)

Answer 22

Blue star emits light at higher energy than red star (1)
Blue has shorter wavelength/higher frequency than red (1)
So blue star has higher surface temperature than red (1)

Question 23

The Asteroid Belt is part of our Solar System.
Vesta is an asteroid in the Asteroid Belt.
The distance between Vesta and the Sun is 2.4 AU.
1 AU is the distance between the Earth and the Sun.
The intensity of the Sun’s radiation reaching the Earth is 1400 W/m2
1 W = 1 J/s
The intensity of the Sun’s radiation at a distance from the Sun = k/d^2
where K always has the same value.
State the unit of K. (1)

Calculate the intensity of the radiation from the Sun at Vesta. (3)

Answer 23

W (1)

K= 1^2 x 1400 (1)
1400/2.4^2 (1)
240 (1)

Question 24

A ray of light travels through a glass block.
P= ray of incidence Q= ray of refraction
The intensity (brightness) of the light at Q is less than the intensity of the light at P.
Explain the decrease in intensity as the light travels from P to Q. (3)

Answer 24

Some light is reflected (1)
At the top edge (1)
Some light is absorbed (1)
by the glass (1)

Question 25

The Asteroid Belt is part of our Solar System.
Vesta is an asteroid in the Asteroid Belt.
Energy is transferred from the Sun to Vesta by radiation.
Explain why the temperature on Vesta does not continue to rise, even though it is absorbing energy from the Sun. (3)

Answer 25

Vesta also radiates (energy) (1)
The same amount of energy it absorbs (1)
In the same time (1)

Question 26

Gamma radiation can be used in food processing to irradiate food.
Explain why some food is irradiated with gamma radiation. (2)

Answer 26

To preserve food (1)
By killing bacteria (1)
Gamma is very penetrating, so reaches all the food (1)
Sterilising (1)

Question 27

Explain what can happen to the body if a person has a prolonged exposure to gamma rays. (2)

Answer 27

Damage to cells (1)
Because gamma rays are ionising/high frequency/very energetic (1)
Causing mutation/cancer (1)

Question 28

X-rays can be useful and harmful to humans.
State one way that x-rays are useful to humans. (1)
State one way that x-rays are harmful to humans. (1)

Answer 28

Seeing broken bones (1)
Radiotherapy (1)
Detecting cracks in metals (1)
Airport security (1)
Observing the internal structure of objects (1)

Can cause cancer/bones (1)
Damages/harms cell & tissue (1)
Mutates DNA/cells (1)

Question 29

bee’s wings flap up and down with a frequency of 230 Hz.
This is a frequency of (1)

A infrasound
B sonar
C sound
D ultrasound

Answer 29

Sound

Question 30

A scientist wrote this sentence:
“Ultraviolet radiation is harmful to humans but useful to honey bees.”
Suggest what the scientist means by this sentence. (2)

Answer 30

harmful effect e.g. damage to {skin (cells) / cancer / mutation / eyes} (1)
bee can ‘see’ objects reflecting UV radiation (1)
allows bees to find (more) food (1)
discussion of different (intensities /) {brightnesses / amounts} (1)
discussion of time of exposure compared to life span (1)

Question 31

State which type of wave can be split into different colours. (1)
State which type of wave has the longest wavelength. (1)
State one type of wave that is ionising. (1)

Answer 31

Visible light (1)
Radio waves (1)
Gamma/X-rays/UV (1)

Question 32

The Sun emits all the waves in the electromagnetic spectrum.
Explain why all these waves take the same time to travel to Earth from the Sun. (2)

Answer 32

Travel with the same speed (1)
In a vacuum (1)

Question 33

Infrared and ultraviolet waves have different frequencies.
Both types of wave can have harmful effects on human beings.
Describe the harmful effects of infrared and UV waves, relating them to the frequencies of the waves. (6)

Answer 33

• Harmful effects include (skin) burns, eye damage, (skin) cancer, cell damage, mutation
• IR and UV are on either side of visible light (in the em spectrum)
• UV has shorter wavelength than IR
• UV has higher frequency than IR
• higher energy (associated) with UV
• IR causes (skin) burns
• UV causes damage to eyes / (skin) cancer / damage to cells (not just damage to skin) / sunburn
• (potential) danger increases with frequency

Question 34

X-rays are ionising radiation.
State one other ionising radiation in the electromagnetic spectrum. (1)

Answer 34

Gamma

Question 35

State one use of an ionising radiation. (1)

Answer 35

UV - sun beds, sterilise, detect bank notes
X-ray - viewing broken bones/internal organs, airport security
Gamma - treat/cure cancer, kill cells

Question 36

State one way in which microwave radiation can be harmful to people. (1)

Answer 36

Heating of body/internal cells/organs/tissue (1)
Heating/boiling water in the body (1)

Question 37

The microwaves used in ovens have a frequency of about 2450 MHz.
Mobile phones emit microwaves with a frequency of about 2000 MHz.
Microwave ovens have shielding to protect people from the microwave radiation.
Suggest why the same shielding is not necessary for mobile phones. (3)

Answer 37

Phones use lower frequencies (1)
Lower frequency = lower energy (1)
Lower frequency/energy, less danger (1)
Phones emit less radiation (1)
Phones are less powerful (1)

Question 38

Cobalt-60 decays by emitting gamma radiation.
Explain what happens to the mass of a cobalt-60 atom when a gamma ray is emitted. (2)

Question 39

Gamma radiation from cobalt-60 can be used to destroy tumours.
Gamma radiation is used to destroy a brain tumour.
Describe what the shield is used for. (2)

Answer 39

Protects/stops radiation escaping (1)
Affecting doctor/operater/nurse (1)

Question 40

Gamma radiation from cobalt-60 can be used to destroy tumours.
Suggest two advantages that this kind of treatment has over other forms of treatment for tumours. (2)

Answer 40

non invasive / no surgery required (1)
no radioactive substances left in the body (1)
no anaesthetic used patient does not become radioactive (1)
outpatient procedure (1)
does not affect the whole body (1)
(accurate) targeting of tumour (1)
painless (at the time) for the patient (1)
procedure (may be) quicker (1)

Question 41

Explain why several beams of gamma radiation are used instead of just one, for the treatment of a brain tumour (2)

Answer 41

Target beams concentrate/focus on tumour (1)
Avoid damage to healthy cells/tissue (1)
Reaching all parts of the tumour (1)

Question 42

Images of hands can be made using different parts of the electromagnetic spectrum.
Both images give information about a hand.
Suggest what information the infrared image gives about a hand. (2)

Answer 42

Patches/shaded area/colours (1)
Indication of temperature/heat (1)

Question 43

Explain why taking an X-ray image of a hand is more dangerous than taking an infrared image. (2)

Answer 43

X-ray mutates/damages cells/DNA (1)
Energy/frequency/wavelength is different (1)
X-rays have a higher frequency/shorter wavelength (1)

Question 44

A glass prism can be used to turn an image the right way up.
Total internal reflection occurs at Q.
Explain why total internal reflection occurs at Q. (2)

Answer 44

Angle of incidence in glass (1)
Is greater than critical angle (1)

Question 45

If light bends towards the normal (1)

A frequency decreases
B frequency increases
C speed decreases
D speed increases

Answer 45

speed decreases

Question 46

Light waves and sound waves are both used in the diagnosis and treatment of medical conditions.
A doctor uses an endoscope to look inside the body of a patient.
Explain how optical fibres are used in endoscopes. (3)

Answer 46

Optical fibres bend (1)
Some fibres carry light to the inside of a patient (1)
Some fibres transmit the reflected light (1)
Light passes up/down fibres by total internal reflection (1)
Light is reflected inside the patient (1)
Image is analysed by computer (1)

Question 47

Describe how ultrasound can be used as a medical treatment for illness or injury. (2)

Answer 47

Breaks/blasts/smashes (1)
Kidney stones (1)
OR
Energy absorbed (1)
To help repair muscle tissue (1)
OR
Use of gel (1)
To prevent loss of intensity (1)

Question 48

State two advantages of using a camera, rather than the unaided eye, for studying stars. (2)

Answer 48

Measurement can be taken (1)
Permanent record/evidence (1)
Can be magnified (1)
Can detect waves outside of visible part of spectrum (1)
Long exposure (1)

Question 49

Galileo observed the moons of Jupiter.
Explain how these observations helped to change scientists’ ideas about the Universe. (3)

Answer 49

Geocentric model was initially believed in (1)
Observation of moons orbiting Jupiter rather than earth (1)
Heliocentric model then preferred (1)

Question 50

light rays are present in a reflecting telescope.
Describe what the mirrors and the eyepiece do to the light rays to form an image of a distant star. (3)

Answer 50

Reflection of light at either mirror (1)
Curved mirror focuses on the light (1)
Mirror inverts (1)
Lens magnifies image (1)
Image is formed where the light rays cross (1)

Question 51

Explain an advantage of using a telescope instead of the naked eye to look at stars. (2)

Answer 51

Collects more light (1)
Produces a magnified/bigger image (1)
Shows more detail (1)
Shows stars the naked eye is unable to see (1)
Can observe stars day and night (1)

Question 52

When waves go from deep water to shallow water, the (1)

A frequency decreases
B wavelength decreases
C frequency increases
D wavelength increases

Answer 52

wavelength decreases

Question 53

A floating buoy is used to warn boats about shallow water.
The buoy has a lamp and a bell.
Explain the difference between transverse and longitudinal waves by referring to sound from the bell and the light from the lamp. (3)

Answer 53

Light waves are transverse/sound waves are longitudinal (1)
In transverse waves, oscillations are perpendicular to the direction the wave is travelling (1)
In longitudinal waves, oscillations are parallel to the direction the wave is travelling (1)

Question 54

A student investigates how light behaves as it leaves a clear plastic semi-circular block.
Describe how the student can make sure the light does not change direction as it enters the block. (2)

Answer 54

Shine the light along a radius (1)
By marking it on the paper before putting the block down (1)

Question 55

Describe what happens to the ray of light when the angle of incidence is increased beyond the critical angle. (2)

Answer 55

All light is reflected (1)
Back inside block (1)