IGCSE · 3 · structured
Waves · Question 9
Waves · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- routine
- Marks
- 8
- Topics
- 1
- Answer
- Complete
The electromagnetic spectrum is a family of transverse waves that all travel at the same speed in a vacuum, 3.0 × 10⁸ m/s.
- (a)
State State one property, other than their speed in a vacuum, that all electromagnetic waves share.
1 mark - (b)
Identify Identify the region of the electromagnetic spectrum used for each of the following, and give one different region for each: (i) cooking food in an oven that heats from the outside; (ii) sterilising medical equipment.
2 marks - (c)
Calculate A radio station broadcasts at a frequency of 95.8 MHz. Calculate the wavelength of the waves it emits.
3 marks - (d)
Describe Describe one harmful effect of excessive exposure to ultraviolet radiation, and state one way of reducing the risk.
2 marks
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(a)
State State one property, other than their speed in a vacuum, that all electromagnetic waves share.
Answer the command word directly and use precise physical vocabulary. Include only the distinct features or facts that earn marks, without burying them in unrelated background information.
- 1
any one of: they are transverse; they transfer energy; they can travel through a vacuum; they can be reflected and refracted
(b)
Identify Identify the region of the electromagnetic spectrum used for each of the following, and give one different region for each: (i) cooking food in an oven that heats from the outside; (ii) sterilising medical equipment.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
For cooking food from the outside, the electromagnetic region is infrared radiation.
- 2
(ii) gamma rays (accept ultraviolet for surface sterilisation)
(c)
Calculate A radio station broadcasts at a frequency of 95.8 MHz. Calculate the wavelength of the waves it emits.
List the given quantities with units, identify the required quantity, write the governing relationship before substituting, and keep extra digits until the final line so rounding does not distort the result.
- 1
λ = v / f
- 2
λ = 3.0 × 10⁸ / 95.8 × 10⁶
- 3
λ = 3.1 m
(d)
Describe Describe one harmful effect of excessive exposure to ultraviolet radiation, and state one way of reducing the risk.
Answer the command word directly and use precise physical vocabulary. Include only the distinct features or facts that earn marks, without burying them in unrelated background information.
- 1
damage to surface cells / skin ageing / skin cancer / eye damage such as cataracts
- 2
wear sunscreen, sunglasses or protective clothing; limit exposure at midday
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