Mark Scheme (Results) January 2021 Pearson Edexcel International GCSE In Physics (4PH1) Paper 2P

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Question number Answer Notes Marks 1 (a) any two from: ignore references to frequency and wavelength 2 MP1. light waves are transverse and sound waves are longitudinal; MP2. light travels fast... er than sound; condone ‘different speeds’ MP3. light can travel through vacuum but sound waves can’t; (b) (i) B (microwaves); 1 A is incorrect because gamma rays have a shorter wavelength than infrared C is incorrect because ultraviolet rays have a shorter wavelength than infrared D is incorrect because visible light waves have a shorter wavelength than infrared (ii) B (heating lamps); 1 A is incorrect because ultraviolet rays are used in fluorescent lamps C is incorrect because there is too much interference from the Earth for infrared to be used for satellite transmissions D is incorrect because gamma rays are used to sterilise medical equipment (iii) D (skin burns); 1 A is incorrect because infrared is not absorbed by the retina B is incorrect because infrared is non-ionising C is incorrect because infrared cannot penetrate into the body to cause internal heatingTotal for Question 1 = 7 marks (c) trace drawn with higher amplitude throughout; allow variable amplitude 2 trace drawn with higher frequency throughout; allow variable amplitude e.g.Question number Answer Notes Marks 2 (a) 2; 1 (b) all rows correct;; 2 any 2 rows correct; e.g. (c) any two from: do not penalize use of atom for nucleus for more than one mark 2 MP1. neutrons absorbed by another nucleus; MP2. uranium-235 named; MP3. nucleus splits, releasing more neutrons (and process repeats); Total for question 2 = 5 marks [Show More]

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