OCR · GCSE · Physics
Course version: J249 · Version from Sept 2018
Describe how ultraviolet waves, X-rays and gamma rays can have hazardous…
Full specification wording
The electromagnetic spectrum: describe how ultraviolet waves, X-rays and gamma rays can have hazardous effects, notably on human bodily tissues
Ultraviolet, X-rays and gamma rays sit at the high-frequency, short-wavelength end of the electromagnetic spectrum, so each photon carries a relatively large amount of energy.
Checked against the OCR J249 specification (opens in a new tab) on .
- Point 8 of 9
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Ultraviolet, X-rays and gamma rays sit at the high-frequency, short-wavelength end of the electromagnetic spectrum, so each photon carries a relatively large amount of energy. That energy can be transferred to atoms and molecules in living tissue, ionising them or breaking chemical bonds. Ultraviolet is mostly absorbed by the skin and eyes, so overexposure can burn the skin, damage the eyes and raise the long-term risk of skin cancer. X-rays penetrate further and are absorbed by denser tissue such as bone; a large dose can damage cells and increase cancer risk, which is why radiographers limit exposure and shield patients. Gamma rays penetrate deeply and can damage cells throughout the body, so sources are heavily shielded and handled remotely.
What earns the marks
- Identifies ultraviolet, X-rays and gamma rays as the high-frequency, high-energy end of the electromagnetic spectrum.
- States that these waves can ionise atoms or break chemical bonds in living cells.
- Links ultraviolet exposure to skin burns, eye damage or increased skin-cancer risk.
- Explains that X-rays and gamma rays penetrate tissue and can damage cells, raising cancer risk at high dose.
- Recognises that the hazard depends on the energy of the radiation and the dose received.
Common mistakes and how to put them right
Confuses the order of the spectrum and places ultraviolet below visible light.
Put it right: Ultraviolet lies just beyond violet, with X-rays and gamma rays at higher frequency still.
Assumes all three waves are stopped by skin.
Put it right: Note that X-rays and gamma rays penetrate deeply while ultraviolet is largely absorbed near the surface.
Treats the hazard as harmless at any dose.
Put it right: Recognise that risk rises with energy and with the amount of exposure received.
Exam tips
- Read the question stem for the word 'hazardous' and choose the option that names damage to living tissue, not merely a property of the wave.
- Eliminate options that describe low-energy waves such as radio or microwaves as ionising.
- Check whether the option links the wave to a specific effect such as skin burn, cell damage or cancer risk rather than a vague statement.
Try the lesson
The start of the The electromagnetic spectrum: describe how ultraviolet waves, X-rays and gamma rays can have hazardous effects, notably on human bodily tissues lesson, made from checked teaching notes for this specification point.
Have a go first
Why can ultraviolet radiation from the Sun damage human skin?
Listen
Ultraviolet, X-rays and gamma rays sit at the high-frequency, short-wavelength end of the electromagnetic spectrum, so each photon carries a relatively large amount of energy. That energy can be transferred to atoms and molecules in living tissue, ionising them or breaking chemical bonds. Ultraviolet is mostly absorbed by the skin and eyes, so overexposure can burn the skin, damage the eyes and raise the long-term risk of skin cancer. X-rays penetrate further and are absorbed by denser tissue such as bone; a large dose can damage cells and increase cancer risk, which is why radiographers limit exposure and shield patients. Gamma rays penetrate deeply and can damage cells throughout the body, so sources are heavily shielded and handled remotely. A strong answer earns marks for these points. Identifies ultraviolet, X-rays and gamma rays as the high-frequency, high-energy end of the electromagnetic spectrum. States that these waves can ionise atoms or break chemical bonds in living cells. Links ultraviolet exposure to skin burns, eye damage or increased skin-cancer risk. Explains that X-rays and gamma rays penetrate tissue and can damage cells, raising cancer risk at high dose. Exam tip: Read the question stem for the word 'hazardous' and choose the option that names damage to living tissue, not merely a property of the wave.
Key words
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High-energy end of the electromagnetic spectrum
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Ionisation and cell damage
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Ultraviolet effects on skin and eyes
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Penetration and dose of X-rays and gamma rays
Try answering aloud or in your head before turning the card.
See every definition
- High-energy end of the electromagnetic spectrum
- Ultraviolet, X-rays and gamma rays sit at the high-frequency, short-wavelength end, so each photon carries a relatively large amount of energy.
- Ionisation and cell damage
- Energy can be transferred to atoms and molecules in living tissue, ionising them or breaking chemical bonds.
- Ultraviolet effects on skin and eyes
- Mostly absorbed by the skin and eyes, so overexposure can burn the skin, damage the eyes and raise the long-term risk of skin cancer.
- Penetration and dose of X-rays and gamma rays
- X-rays penetrate further and are absorbed by denser tissue such as bone, while gamma rays penetrate deeply and can damage cells throughout the body; a large dose can damage cells and increase cancer risk.
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