DP Physics (last assessment 2024)

Question 21M.2.HL.TZ1.c.ii

Date	May 2021	Marks available	[Maximum mark: 2]	Reference code	21M.2.HL.TZ1.c.ii
Level	HL	Paper	2	Time zone	TZ1
Command term	Calculate	Question number	c.ii	Adapted from	N/A

c.ii.

[Maximum mark: 2]

21M.2.HL.TZ1.c.ii

A painting is protected behind a transparent glass sheet of refractive index n_glass. A coating of thickness w is added to the glass sheet to reduce reflection. The refractive index of the coating n_coating is such that n_glass > n_coating > 1.

The diagram illustrates rays normally incident on the coating. Incident angles on the diagram are drawn away from the normal for clarity.

The painting contains a pattern of red dots with a spacing of 3 mm. Assume the wavelength of red light is 700 nm. The average diameter of the pupil of a human eye is 4 mm. Calculate the maximum possible distance at which these red dots are distinguished.

[2]

Markscheme

$θ = « 1.22 \frac{λ}{b} = 1.22 \frac{700 \times 10^{- 9}}{4 \times 10^{- 3}} = » 2.14 \times 10^{- 4} « rad »$ ✓

$D = 14 « 0.05 m »$ ✓

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Additional higher level (AHL)

Additional higher level (AHL) » Topic 9: Wave phenomena » 9.4 – Resolution

Additional higher level (AHL) » Topic 9: Wave phenomena

Question 21M.2.HL.TZ1.c.ii

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