The list shows the electromagnetic spectrum in order of increasing frequency, with two groups missing.
radio waves A infrared visible light B X-rays gamma rays
(a) Name the groups A and B. [2]
(b) Give one use of infrared radiation. [1]
(c) State one harmful effect of excessive exposure to ultraviolet radiation. [1]
- (a) A = microwaves(1)
- (a) B = ultraviolet(1)
- (b) any one from: heaters / grills / toasters / cooking; night-vision equipment / thermal imaging cameras; remote controls; optical fibre communication; security (intruder) alarms; accept any other valid use(1)
- (c) damage to surface cells / skin cancer / sunburn / premature ageing of the skin allow damage to eyes / blindness / cataracts; ignore 'cancer' unqualified(1)
- Answer: (a) A microwaves, B ultraviolet (b) e.g. TV remote controls (c) e.g. skin cancer
- Examiner tip: Learn the order with frequencies increasing from radio to gamma; wavelength decreases in the same direction.