Physics · Oct / Nov 2022 · Paper 41 · Question 6
0625
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The question as text
The red light produced by a laser is monochromatic.
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6(a)[1]
(light of a) single frequency
6(b)(i)[2]
angle of incidence is 0°
(hence) angle of refraction is 0°
or
all the wavefront hits the plastic at the same time
all slows down at the same time
6(b)(ii)[4]
1.8 × 108 m / s
n = 1 / sin c in any form or n = 1 / sin 37°
(n =) 1.7
vpl = v0 / n in any form or 3.0 × 108 / 1.7 or 3.0 × 108 × sin 37°
6(b)(iii)[3]
critical angle (for blue light) < 37° or critical angle for red (light) is 37°
angle of incidence (of blue light) greater than its critical angle (in plastic)
total internal reflection or all the (blue) light reflects or no (blue) light
leaves the glass / refracts / travels in air along the straight edge
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