All EM waves can transfer energy, from a source to an absorber.
Only UV, X-ray and gamma frequencies of EM wave cause ionisation. The higher the frequency, the more ionising.
Ionising radiation can damage cells, cause genes to mutate and increase the risk of cancer.
UV is used in lighting and to disinfect water. It causes tanning/sunburn. It increases the risk of skin cancer.
X- and gamma rays are used in medical imaging. Gamma rays are used to kill cancer cells and to sterilise food/equipment.

Keywords

Energy transfer - Electromagnetic waves transfer energy because stores of energy decrease when they are emitted and increase when they are absorbed.
Ionisation - Ionisation is the process of an atom losing or gaining electrons so become charged/becoming an ion.
Ultraviolet - Ultraviolet means EM radiation with frequencies greater than visible light but lower than X–rays.
X-rays - X-rays are EM radiation with frequencies greater than ultraviolet but lower than gamma rays.
Gamma rays - Gamma rays are the highest frequency electromagnetic waves.

Common misconception

Gamma rays are always higher energy (or power), or more dangerous, than other frequencies of EM radiation.

EM waves transfer their energy in 'chunks' or 'packets'. The energy transferred by one 'packet' of radiation (and so its ionising ability) does depend on frequency. But the power of a beam of radiation depends on the intensity of the radiation too.

Students need to understand in what sense gamma rays transfer most energy (since more intense lower freq. radiation can have greater power). This lesson describes gamma as transferring more energy per 'chunk' or 'packet' of radiation rather than per each 'ray' or 'wave' which is less accurate/clear.

Teacher tip

Content guidance

Depiction or discussion of sensitive content

Supervision

Adult supervision recommended

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.

Electromagnetic radiation that has longer wavelengths than X–rays and shorter wavelengths than light is called radiation.

Correct Answer: ultraviolet, utra-violet, ultra violet, UV, U V

Q2.

Match the following types of electromagetic radiation to the correct description.

Correct Answer:Radio waves ...,have the lowest frequencies of any EM radiation.

have the lowest frequencies of any EM radiation.

Correct Answer:Gamma rays ...,have the highest frequencies of any EM radiation.

have the highest frequencies of any EM radiation.

Correct Answer:Infrared waves ...,have frequencies higher than microwaves and lower than visible light.

have frequencies higher than microwaves and lower than visible light.

Q3.

Which of the following statements about electromagnetic waves are correct?

All electromagnetic waves have the same frequency in a vacuum.

All electromagnetic waves have the same wavelength in a vacuum.

Correct answer: All electromagnetic waves transfer energy.

Correct answer: All electromagnetic waves have the same speed in a vacuum.

Q4.

Which of the following types of particle is found outside the nucleus of an atom?

Correct answer: electron

neutron

proton

Q5.

Match each of the following types of particle with its type of electric charge.

Correct Answer:electron,negative

negative

Correct Answer:neutron,neutral

neutral

Correct Answer:proton,positive

positive

Q6.

An atom contains 6 protons, 5 neutrons and 6 electrons. What is the overall electric charge on the atom?

6–

1–

Correct answer: 0

Exit quiz

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6 Questions

Q1.

Electromagnetic (EM) radiation can transfer energy to objects. Match each of the following types of EM radiation with an effect that can occur when it transfers energy.

Correct Answer:ultraviolet,sunburn

sunburn

Correct Answer:gamma,destruction of cancer cells

destruction of cancer cells

Correct Answer:infrared,heating of an object’s surface

heating of an object’s surface

Correct Answer:microwaves,heating of the water inside food

heating of the water inside food

Correct Answer:light,generation of electricity by a solar panel

generation of electricity by a solar panel

Q2.

Some types of electromagnetic radiation can make an atom gain or lose one or more electrons and become charged. A charged atom is called an ...

Correct Answer: ion

Q3.

Which of the following is the most strongly ionising type of electromagnetic radiation?

Correct answer: gamma rays

infrared waves

microwaves

ultraviolet waves

X–rays

Q4.

Which of the following increases the potential harm when electromagnetic radiation hits a living organism?

Correct answer: increasing the intensity of the radiation

Correct answer: increasing the frequency of the radiation

increasing the wavelength of the radiation

Correct answer: increasing how long exposure to the radiation lasts

Q5.

Which of the following can happen when an atom absorbs radiation?

Correct answer: An electron becomes ‘excited’.

Correct answer: An electron is ejected from the atom.

An electron moves to a lower energy level.

Correct answer: An electron moves to a higher energy.

Q6.

Match each of the following types of electromagnetic radiation to one of its uses.

Correct Answer:ultraviolet,detecting fake bank notes

detecting fake bank notes

Correct Answer:X–rays,scanning bags at security checks

scanning bags at security checks

Correct Answer:gamma rays,sterilising medical equipment

sterilising medical equipment