The diagram shows a ray of light incident on a boundary between air and glass - Edexcel - GCSE Physics - Question 2 - 2014 - Paper 1
Question 2
The diagram shows a ray of light incident on a boundary between air and glass.
The critical angle for glass in air is 42°.
Which of these diagrams shows the ray of... show full transcript
Worked Solution & Example Answer:The diagram shows a ray of light incident on a boundary between air and glass - Edexcel - GCSE Physics - Question 2 - 2014 - Paper 1
Step 1
Identify the Critical Angle
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Answer
The critical angle for glass in air is given as 42°. This means that any angle of incidence greater than 42° within the glass will result in total internal reflection.
Step 2
Analyze the Incident Angle
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Answer
In the diagram, the incident angle is given as 30°. This angle is less than the critical angle (42°), indicating that refraction will occur rather than total internal reflection.
Step 3
Determine the Ray Direction
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Answer
Since the incident angle (30°) is less than the critical angle (42°), the ray of light will exit towards the air at a refracted angle that will be greater than 30° but less than 42°. Thus, it cannot be reflected back into the glass.
Step 4
Select the Correct Diagram
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Answer
Among the shown diagrams (A, B, C, D), the correct response, indicating the direction of the ray after it meets the boundary, must demonstrate the ray bending away from the normal as it enters the air. This is consistent with the conditions of refraction.
