A sports centre uses a mobile ultraviolet lamp to kill microorganisms on the floor of an empty changing room. The illuminated band is 1.2 m long in the direction of travel. Each point on the floor must be illuminated for at least 6.0 seconds. The available speeds are 0.10 m/s, 0.20 m/s, 0.30 m/s and 0.60 m/s.
Which option gives the fastest available speed that provides the required exposure, and identifies a harmful effect of the radiation used?
0.60 m/s; damage to surface cells and DNA.
0.10 m/s; internal heating of body tissue.
0.20 m/s; damage to surface cells and DNA.
0.30 m/s; heating mainly near the skin surface.
104 exam-style questions on Edexcel GCSE Physics 5.4 Uses and dangers of EM radiation, covering 5.4.1 Dangers of electromagnetic radiation, 5.4.2 Uses of electromagnetic radiation, 5.4.3 Radio waves and oscillations in circuits, and 5.4.4 Changes in atoms and nuclei generating radiation. Each one has a worked solution and a mark scheme showing where the marks go.