The diagram shows light incident on the centre of a semi circular glass block - Edexcel - GCSE Physics - Question 6 - 2016 - Paper 1
Question 6
The diagram shows light incident on the centre of a semi circular glass block. Angle X is less than the critical angle.
Complete the sentence by putting a cross (X)... show full transcript
Worked Solution & Example Answer:The diagram shows light incident on the centre of a semi circular glass block - Edexcel - GCSE Physics - Question 6 - 2016 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The ray of light emerges from the glass block along the path towards C.
Step 2
In the diagram, the angle Y is greater than the critical angle.
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Answer
Since angle Y is greater than the critical angle, the light will undergo total internal reflection. Draw the reflected ray at point P, demonstrating that it does not enter the semicircular glass block.
Step 3
Explain why the light changes direction when it passes from air into the glass lens.
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Answer
When light travels from air into glass, it slows down due to the higher refractive index of the glass compared to air. This change in speed causes the light to change direction, bending towards the normal line, which is a result of Snell's Law.
Step 4
Calculate the power of this lens.
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Answer
The power of a lens (P) is given by the formula:
P = rac{1}{f}
where f is the focal length in meters. Substituting the focal length,
P = rac{1}{0.25} = 4.0 ext{ diopters}
Step 5
Discuss what is happening to the light in each example.
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Answer
In the Fibre optic lamp, light travels through the optical fiber by multiple internal reflections, allowing it to be transmitted over long distances without significant loss. The light rays are guided along the fiber due to the principle of total internal reflection.
In the Plane mirror, the light rays striking the mirror reflect at the same angle they arrived, adhering to the law of reflection, which states that the angle of incidence is equal to the angle of reflection. This creates a clear and inverted image of the object in front of the mirror.
