DP Physics (last assessment 2024)

Question 20N.3.HL.TZ0.a

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.3.HL.TZ0.a
Level	HL	Paper	3	Time zone	TZ0
Command term	Calculate	Question number	a	Adapted from	N/A

[Maximum mark: 1]

20N.3.HL.TZ0.a

The light from a distant galaxy shows that $z = 0.11$ .

Calculate the ratio $\frac{size of the universe when the light was emitted}{size of the universe at present}$ .

[1]

Markscheme

« $\frac{R_{0}}{R} =$ »

$\frac{1}{1.11}$ OR $0.90$ OR $90 %$ ✓

Examiners report

Many candidates got the ratio upside down and ended up with R/R₀ as 1.11.

This was not accepted as it would have required an identification of the variables. Perhaps candidates need to look more carefully at which R is which here. R is the current value of the scale factor in the data book, so R₀/R = 0.9 was required.

Syllabus sections

Option D: Astrophysics

Option D: Astrophysics » Option D: Astrophysics (Core topics) » D.3 – Cosmology

Option D: Astrophysics » Option D: Astrophysics (Core topics)

Question 20N.3.HL.TZ0.a

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