DP Physics (last assessment 2024)

Question 20N.3.SL.TZ0.c

Date	November 2020	Marks available	[Maximum mark: 3]	Reference code	20N.3.SL.TZ0.c
Level	SL	Paper	3	Time zone	TZ0
Command term	Calculate	Question number	c	Adapted from	N/A

[Maximum mark: 3]

20N.3.SL.TZ0.c

A beam of monochromatic light from infinity is incident on a converging lens A. The diagram shows three wavefronts of the light and the focal point $f$ of the lens.

The screen is removed and the image is used as the object for a second diverging lens B, to form a final image. Lens B has a focal length of $2.00 cm$ and the final real image is $8.00 cm$ from the lens. Calculate the distance between lens A and lens B.

[3]

Markscheme

$A : \frac{1}{- 2.0} = \frac{1}{8} + \frac{1}{u}$ ✓

$u = - 1.6 « cm »$ ✓

distance necessary = $« 36.0 - 1.6 = » 34.4 « cm »$ ✓

Allow [2 max] for ECF for no negative in MP1. Gives $u = 2.7$ and distance of $38.7 « cm »$

Allow ECF from (b) in MP3.EG use of $0.4 m / 40 c m$ .

Syllabus sections

Option C: Imaging

Option C: Imaging » Option C: Imaging (Core topics) » C.1 – Introduction to imaging

Option C: Imaging » Option C: Imaging (Core topics)

Question 20N.3.SL.TZ0.c

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