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Question 20N.1A.SL.TZ0.12

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Date November 2020 Marks available [Maximum mark: 1] Reference code 20N.1A.SL.TZ0.12
Level SL Paper 1A Time zone TZ0
Command term Question number 12 Adapted from N/A
12.
[Maximum mark: 1]
20N.1A.SL.TZ0.12

Wavefronts travel from air to medium Q as shown.

What is the refractive index of Q?

A.  sin30°sin45°

B.  sin45°sin30°

C.  sin45°sin60°

D.  sin60°sin45°

[1]

Markscheme

B

Examiners report

This has a negative discrimination index and the majority of candidates chose option C which would be correct if we were considering rays but the question asks about wavefronts. It must be stressed that it is important to read the question carefully and not skim over the introductory stem. In this type of question students are advised to draw the rays on the diagram perpendicular to the wavefronts to make it easier to work out which angles to use.

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