Practise Uses and applications of EM 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.
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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