DP Physics (last assessment 2024)

Question 20N.3.HL.TZ0.21b

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.3.HL.TZ0.21b
Level	HL	Paper	3	Time zone	TZ0
Command term	Outline	Question number	b	Adapted from	N/A

[Maximum mark: 1]

20N.3.HL.TZ0.21b

(b)

Outline how Hubble’s law is related to $z$ .

[1]

Markscheme

«Hubble’s » measure of v/recessional speed uses redshift which is $z$
OR
redshift ( $z$ ) of galaxies is proportional to distance «from earth»
OR
combines $v = H d$ AND $z = \frac{v}{c}$ into one expression, e.g. $z = \frac{H d}{c}$ ✓

OWTTE

Examiners report

To show the link between z and Hubble's law many rearranged formulae to obtain zc = Hd or similar. Others stated that Hubble used redshift z to determine that v was proportional to distance. Either approach was allowed.

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.TZ0.21b

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