Two transparent prisms A and B of different refractive indices are placed in contact to produce a rectangular block - AQA - A-Level Physics - Question 6 - 2022 - Paper 1
Question 6
Two transparent prisms A and B of different refractive indices are placed in contact to produce a rectangular block.
Figure 12 shows the path of a ray, incident nor... show full transcript
Worked Solution & Example Answer:Two transparent prisms A and B of different refractive indices are placed in contact to produce a rectangular block - AQA - A-Level Physics - Question 6 - 2022 - Paper 1
Step 1
06.1 Explain how the path of the ray shows that the refractive index of A is greater than the refractive index of B.
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Answer
The path of the ray indicates that as it travels from air into prism A, the ray bends towards the normal due to a higher refractive index (1.62) compared to air. When the ray reaches prism B, it bends away from the normal, indicating a lower refractive index (1.35). This behavior aligns with Snell's law, where a greater refractive index causes light to bend towards the normal.
Step 2
06.2 Show that the angle of refraction of the ray in B is about 60°.
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Answer
To find the angle of refraction in prism B, we apply Snell's Law:
n1imesextsin(heta1)=n2imesextsin(heta2)
Here,
n1=1.62 (for prism A)
heta1=43° (the angle of incidence)
n2=1.35 (for prism B)
Setting the values in the equation:
1.62imesextsin(43°)=1.35imesextsin(heta2)
After calculating, we find:
heta2=extabout60°
Step 3
06.3 Draw, on Figure 12, the path of the ray immediately after it reaches P. Justify your answer with calculations.
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Answer
After the ray reaches point P, it again encounters the boundary going from prism B to air. We can continue using Snell's Law:
Setting:
n2=1.35 (for prism B)
n3=1.00 (for air)
heta2=60° (angle of refraction from previous calculation)
Using Snell's Law again:
1.35imesextsin(60°)=1.00imesextsin(heta3)
Calculating for heta3 gives:
heta3=75°
Thus, the ray exits into the air at approximately 75° with the normal line.