Physics · May / June 2023 · Paper 41 · Question 5
0625
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The question as text
Fig. 5.1 shows a block ABCD made of glass that has a refractive index of 1.5. The block has one curved side AB and three straight sides, BC, CD and DA. glass block monochromatic light air B P θ C D A Fig. 5.1 There are right angles at C and D. The curved side AB is one quarter of the circumference of a circle that has its centre at point P. A ray of monochromatic light enters the block through the curved side AB and strikes side BC at P. Some light emerges into the air and some is reflected.
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5(a)[1]
(light / electromagnetic radiation) of a single frequency
5(b)[2]
angle of incidence / i = 0 OR incident ray along normal
OR all of wavefront enters block at same time
angle of refraction / r = 0 OR no refraction
OR whole wavefront slows down at same time
5(c)[2]
(c =) sin–1{1 /1.5} (= 42°)
OR
(c =) sin–1 {1 / n} = 41.8°
n = 1 / sin c OR (c =) sin-1 {1 / n} OR (c =) 41.8°
5(d)(i)[2]
𝜃 / angle of incidence > c / critical angle
all light is reflected
5(d)(ii)[1]
all light is reflected OR reflected ray at 90° to incident ray OR reflected ray is parallel to original ray
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