Practise Uses and applications of electromagnetic waves. 14 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The practical uses of each part of the electromagnetic spectrum and, at Higher tier, why each type of wave is suitable for its use. Expect 'give a use' recall questions, and 2 to 3 mark 'explain why' questions at Higher tier.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Match each EM wave to a useE.g. radio waves: television and radio; X-rays: medical imaging.
4
Give two uses of microwavesSatellite communications and cooking food.
4
Give three uses of infraredElectrical heaters, cooking food and infrared cameras.
5
Give uses of visible light and ultravioletVisible light: fibre optic communications. Ultraviolet: energy-efficient lamps and sun tanning.
7
Explain why microwaves suit satellite communications (HT)Microwaves pass through the Earth's atmosphere, so they can reach satellites in space.
7
Explain why X-rays suit imaging bones (HT)X-rays pass through soft tissue but are absorbed by bone, so bones show up on the image.
8
Explain why gamma rays treat cancer (HT)Gamma rays are ionising and carry a lot of energy, so a carefully aimed beam can kill cancer cells.
X-rays and gamma rays: medical imaging and medical treatments, such as killing cancer cells.
Why each type is suitable (Higher tier only) grade 7+
Radio waves travel long distances through the air and pass through walls, and they are easy to produce and detect with aerials in electrical circuits.
Microwaves pass through the Earth's atmosphere, so signals can travel between the ground and satellites in space. In an oven, microwaves pass a few centimetres into food and are absorbed by the water molecules in it, which heats the food.
Infrared is absorbed by the surfaces of objects and food, transferring energy to their thermal energy stores. All objects emit infrared and hotter objects emit more, so an infrared camera can show temperature differences, even in the dark.
Visible light travels along thin glass fibres by reflecting off the inside walls, and little of it is absorbed by the glass, so signals can be sent a long way.
Ultraviolet: in an energy-efficient lamp, ultraviolet produced inside the tube is absorbed by a coating on the glass, which then gives out visible light. Much less energy is wasted than in a filament lamp. Ultraviolet absorbed by skin makes it tan.
X-rays pass easily through soft tissue but are absorbed by bone, so bones show up clearly on the detector.
X-rays and gamma rays are ionising and carry a lot of energy, so a carefully aimed beam can kill cancer cells.
Explain why a type of EM wave suits a use (Higher tier only)
2 marks7
State the property of the wave: what it passes through and what absorbs it.
Link the property to the use with 'so'.
Example. Explain why X-rays are used to produce images of broken bones.
Show the model answer
X-rays pass through soft tissue such as skin and muscle but are absorbed by bone (1). So the bones show up clearly on the detector, and the break can be seen (1).
Explain how an application works (Higher tier only)
3 marks7
Say where the waves go (e.g. into the food).
Say what absorbs them.
Say what the absorbed energy does.
Example. Explain how a microwave oven heats food.
Show the model answer
The microwaves pass a few centimetres into the food (1). They are absorbed by water molecules in the food (1). This transfers energy to the food, increasing its temperature (1).
Explain a use and its risk (Higher tier only)
3 marks8
Give the property that makes the wave useful.
Give the effect on the target (e.g. cancer cells).
Give the risk to healthy tissue and how it is reduced.
Example. Gamma rays can be used to treat cancer, but they are also a hazard to healthy tissue. Explain why gamma rays can treat cancer and why the beam is carefully aimed at the tumour.
Show the model answer
Gamma rays are ionising and carry a lot of energy (1), so they can damage and kill cancer cells (1). They can also damage healthy cells and cause mutations, so the beam is aimed to keep the dose to healthy tissue as small as possible (1).
Shortcuts and memory tricks
Walk along the spectrum saying one use for each: radio for radio and TV, micro for satellites and cooking, infrared for heaters and cameras, visible for fibre optics, ultraviolet for lamps and tanning, X-rays and gamma for hospitals.
For 'why is it suitable', ask two questions: what does it pass through, and what absorbs it?
Both microwaves and infrared cook food: microwaves are absorbed by water a few centimetres into the food; infrared is absorbed at the surface.
Where marks are lost
Mixing up infrared and ultraviolet uses, e.g. saying 'ultraviolet cameras' for seeing warm objects in the dark.
Saying microwaves heat food only at the surface. They pass a few centimetres in and are absorbed by the water there.
Giving a use without any explanation when the question says 'explain why'.
Saying X-rays are reflected by bones. They are absorbed.
Exam technique
For 'give a use', one specific use is enough, e.g. 'satellite communications' for microwaves.
In Higher tier 'explain' questions, give the property and then its consequence, joined with 'so' or 'because'.
Learn the uses exactly as the specification lists them: they are the answers examiners expect.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Different types of electromagnetic wave have different uses. Give one use of infrared radiation.
Electric heaters (or cooking, or infrared cameras).
Night-vision goggles form an image of a person in the dark by detecting the radiation the person emits. Which type of electromagnetic wave do they detect?
Infrared
Give one reason why infrared, rather than visible light, is used in a TV remote control.
It is invisible (or it reflects usefully off surfaces to reach the receiver).
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Different types of electromagnetic wave have different uses.
(a) Name the type of electromagnetic wave used for each application. Fibre optic communications Satellite communications Sun tanning Producing images of broken bones[4]
Electromagnetic waves are used in many different ways.
(a) Explain why microwaves are used to communicate with satellites in orbit.[2]
(b) A security camera uses infrared radiation. It can produce images of people in complete darkness. Explain how.[2]
(c) Explain why infrared radiation is suitable for heating a room with an electric heater.[1]
(d) Radio waves are used to broadcast radio and television programmes. Give one reason why radio waves are suitable.[1]
Show the answer and mark scheme
(a)Answer: Microwaves pass through the atmosphere, so signals can travel between the ground and satellites.
microwaves pass through the Earth's atmosphere (without being absorbed or reflected)
so they can reach satellites in space and return to Earth
(b)Answer: People emit infrared radiation, which the camera detects; warmer objects emit more, so people stand out.
people / warm objects emit infrared radiation
the camera detects this infrared (and warmer objects emit more, so they show up against cooler surroundings)
(c)Answer: Infrared is absorbed by objects and people, warming them.
infrared is absorbed by objects / people and transfers energy that increases their temperature
(d)Answer: They travel long distances through the air without being absorbed.
they can travel long distances through the air (without being absorbed) / they can pass through walls / some radio waves are reflected by the upper atmosphere, so they reach receivers beyond the horizon
Question 3Hard6 marks
Ultraviolet, X-rays and gamma rays all have useful applications, but they must be used carefully.
(a) An energy-efficient lamp contains a gas that emits ultraviolet radiation when the lamp is switched on. The inside of the glass tube is coated with a special powder. Explain how the lamp produces visible light.[2]
(b) High-energy X-rays and gamma rays are both used to treat cancer. Explain why they can be used to destroy cancer cells.[2]
(c) During treatment, a beam of gamma rays is directed at a tumour from several different directions, one after another. Each beam passes through the tumour. Suggest why this is better than using a single, stronger beam from one direction.[2]
Show the answer and mark scheme
(a)Answer: The coating absorbs the ultraviolet and emits visible light.
the coating absorbs the ultraviolet radiation
and emits visible light
(b)Answer: They are ionising, so they damage the DNA of the cancer cells and kill them.
they are ionising / carry a lot of energy
so they damage / kill the (cancer) cells, e.g. by damaging their DNA
(c)Answer: The tumour receives the combined dose, but healthy tissue along each path only receives the dose of one weaker beam.
the tumour receives the dose from every beam, so it gets a large total dose
but each region of healthy tissue is crossed by only one (weaker) beam, so it receives a much smaller dose / less damage to healthy cells