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Date November 2017 Marks available 1 Reference code 17N.3.SL.TZ0.13
Level Standard level Paper Paper 3 Time zone Time zone 0
Command term Outline Question number 13 Adapted from N/A

Question

The collision of two galaxies is being studied. The wavelength of a particular spectral line from the galaxy measured from Earth is 116.04 nm. The spectral line when measured from a source on Earth is 115.00 nm.

Outline one reason for the difference in wavelength.

[1]
a.

Determine the velocity of the galaxy relative to Earth.

[2]
b.

Markscheme

galaxies are moving away

OR

space «between galaxies» is expanding

Do not accept just red-shift

a.

«\(\frac{{\Delta \lambda }}{\lambda } = \)» \(\frac{{1.04}}{{115}} = \frac{v}{c}\)

0.009c

Accept 2.7×106 «m s–1»

Award [0] if 116 is used for \(\lambda \)

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

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