DP Physics (last assessment 2024)

Question 20N.3.SL.TZ0.a

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

[Maximum mark: 1]

20N.3.SL.TZ0.a

Show that the apparent brightness $b \propto \frac{A T^{4}}{d^{2}}$ , where $d$ is the distance of the object from Earth, $T$ is the surface temperature of the object and $A$ is the surface area of the object.

[1]

Markscheme

substitution of $L = σ A T^{4}$ into $b = \frac{L}{4 {πd}^{2}}$ giving $b = \frac{σ A T^{4}}{4 {πd}^{2}}$

Removal of constants $σ$ and $4 π$ is optional

Syllabus sections

Option D: Astrophysics

Option D: Astrophysics » Option D: Astrophysics (Core topics) » D.1 – Stellar quantities

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

Question 20N.3.SL.TZ0.a

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