Physics · Oct / Nov 2020 · Paper 42 · Question 7
0625
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The question as text
Fig. 7.1 shows a ray of light passing through an optical fibre. Q P i Fig. 7.1 The optical fibre is made of glass that has a refractive index of 1.4.
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7(a)(i)[1]
total internal reflection OR T.I.R.
7(a)(ii)[2]
sin C = 1 ÷ n in any form OR (C =) sin–1 {1 ÷ 1.4}
(C = sin–1 {1 ÷ 1.4} = sin–1 0.714 =) 46°
7(b)[3]
description of fibre passing to site to be examined / treated
light passes down fibre (to site) AND (image) returns (to sensor / observer)
OR alternative use to endoscopy
extra detail, e.g. laser light source, illuminated organ, image, camera / type of sensor
7(c)[2]
any mention of frequency
(all of light) same / single / one frequency
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