DP Physics (first assessment 2025)

Question 21M.2.HL.TZ2.b

Date	May 2021	Marks available	[Maximum mark: 4]	Reference code	21M.2.HL.TZ2.b
Level	HL	Paper	2	Time zone	TZ2
Command term	Determine	Question number	b	Adapted from	N/A

[Maximum mark: 4]

21M.2.HL.TZ2.b

Monochromatic light of wavelength 633 nm is normally incident on a diffraction grating. The diffraction maxima incident on a screen are detected and their angle θ to the central beam is determined. The graph shows the variation of sinθ with the order n of the maximum. The central order corresponds to n = 0.

Determine a mean value for the number of slits per millimetre of the grating.

[4]

Markscheme

identifies gradient with $\frac{λ}{d}$ OR use of $d \sin θ = n λ$ ✓

gradient = 0.08 OR correct replacement in equation with coordinates of a point ✓

$d = \frac{633 \times 10^{- 9}}{0.080} = « 7.91 \times 10^{- 6} m »$ ✓

$1.26 \times 10^{2} OR 1.27 \times 102 « {mm}^{- 1} »$ ✓

Allow ECF from MP3

Syllabus sections

C. Wave behaviour » C.3 Wave phenomena

Question 21M.2.HL.TZ2.b

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