IB Questionbank

Updates to Questionbank

User interface language: English | Español

Date	November 2019	Marks available	2	Reference code	19N.3.SL.TZ0.11
Level	Standard level	Paper	Paper 3	Time zone	0 - no time zone
Command term	Determine	Question number	11	Adapted from	N/A

Question

Outline how the light spectra of distant galaxies are used to confirm hypotheses about the expansion of the universe.

[2]

a(i).

Light from a hydrogen source in a laboratory on Earth contains a spectral line of wavelength 122 nm. Light from the same spectral line reaching Earth from a distant galaxy has a wavelength of 392 nm. Determine the ratio of the present size of the universe to the size of the universe when the light was emitted by the galaxy.

[2]

a(ii).

Estimate the age of the universe in seconds using the Hubble constant H₀ = 70 km s^–1Mpc^–1.

[2]

b(i).

Outline why the estimate made in (b)(i) is unlikely to be the actual age of the universe.

[1]

b(ii).

Markscheme

spectra of galaxies are redshifted «compared to spectra on Earth» ✔

redshift/longer wavelength implies galaxies recede/ move away from us
OR
redshift is interpreted as cosmological expansion of space ✔

«hence universe expands»

NOTE: Universe expansion is given, so no mark for repeating this.
Do not accept answers based on CMB radiation.

a(i).

ALTERNATIVE 1

$z = \frac{392 - 122}{122} = 2.21$ ✔

$\frac{R}{R_{0}} = « 2.21 + 1 = » 3.21$ ✔

ALTERNATIVE 2

$\frac{R}{R_{0}} = \frac{392}{122}$ ✔

=3.21 ✔

a(ii).

$H = « \frac{70 \times 10^{3}}{(10^{6} \times 3.26 \times 9.46 \times 10^{15})} = » 2.27 \times 10^{- 18} « s^{- 1} »$ ✔

$T = « \frac{1}{2.27 \times 10^{- 18}} = » 4.4 \times 10^{17} s$ ✔

b(i).

because estimate assumes the «present» constant rate of expansion ✔
it is unlikely that the expansion rate of the universe was ever constant ✔
there is uncertainty in the value of H₀ ✔

NOTE: OWTTE

b(ii).

Examiners report

[N/A]

a(i).

[N/A]

a(ii).

[N/A]

b(i).

[N/A]

b(ii).

Syllabus sections

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

Show 34 related questions

17N.3.SL.TZ0.13a: Outline one reason for the difference in wavelength.
16N.3.SL.TZ0.17b: A spectral line in the hydrogen spectrum measured in the laboratory today has a wavelength of...
17M.3.SL.TZ1.10a.i:
State two characteristics of the cosmic microwave background (CMB) radiation.
18N.3.SL.TZ0.13a:
Outline how Hubble measured the recessional velocities of galaxies.
19N.3.SL.TZ0.11b(i):
Estimate the age of the universe in seconds using the Hubble constant H₀ = 70 km s^–1Mpc^–1.
16N.3.SL.TZ0.17a: Identify two other characteristics of the CMB radiation that are predicted from the Hot Big...
17N.3.SL.TZ0.13b:
Determine the velocity of the galaxy relative to Earth.
19M.3.SL.TZ2.14b: Outline how observations of spectra from distant galaxies provide evidence that the universe...
17M.3.SL.TZ1.10b:
Describe how the CMB provides evidence for the Hot Big Bang model of the universe.
17M.3.SL.TZ2.12a:
Describe what is meant by the Big Bang model of the universe.
18M.3.SL.TZ1.12a:
Explain how international collaboration has helped to refine this value.
18M.3.SL.TZ2.12c:
On the graph, one galaxy is labelled A. Determine the size of the universe, relative to its present size, when light from the galaxy labelled A was emitted.
19N.3.SL.TZ0.11a(i): Outline how the light spectra of distant galaxies are used to confirm hypotheses about the...
19N.3.SL.TZ0.11b(ii):
Outline why the estimate made in (b)(i) is unlikely to be the actual age of the universe.
17M.3.SL.TZ2.12b:
State two features of the cosmic microwave background (CMB) radiation which are consistent with the Big Bang model.
19N.3.HL.TZ0.16a(i): Outline how the light spectra of distant galaxies are used to confirm hypotheses about the...
18N.3.HL.TZ0.19a:
Outline how Hubble measured the recessional velocities of galaxies.
18N.3.SL.TZ0.13b:
Using the graph, determine in s, the age of the universe.
19N.3.HL.TZ0.16a(ii):
Light from a hydrogen source in a laboratory on Earth contains a spectral line of wavelength 122 nm. Light from the same spectral line reaching Earth from a distant galaxy has a wavelength of 392 nm. Determine the ratio of the present size of the universe to the size of the universe when the light was emitted by the galaxy.
20N.3.SL.TZ0.16b:
Outline how Hubble’s law is related to $z$ .
20N.3.SL.TZ0.16a:
The light from a distant galaxy shows that $z = 0.11$ .

Calculate the ratio $\frac{size of the universe when the light was emitted}{size of the universe at present}$ .
18N.3.HL.TZ0.19b:
Use the graph to determine the age of the universe in s.
20N.3.HL.TZ0.21b:
Outline how Hubble’s law is related to $z$ .
20N.3.HL.TZ0.21a:
The light from a distant galaxy shows that $z = 0.11$ .

Calculate the ratio $\frac{size of the universe when the light was emitted}{size of the universe at present}$ .
19M.3.SL.TZ2.14ai: A galaxy is 1.6 × 108 ly from Earth. Show that its recessional speed as measured from Earth...
19M.3.HL.TZ1.19b: Suggest why type I a supernovae were used in the study that led to the conclusion that the...
17M.3.SL.TZ1.10c.ii:
Estimate the size of the Universe relative to its present size when the light was emitted by the galaxy in (c).
18M.3.SL.TZ2.12a:
Estimate, using the data, the age of the universe. Give your answer in seconds.
18M.3.SL.TZ2.12b:
Identify the assumption that you made in your answer to (a).
17M.3.SL.TZ1.10c.i:
Determine the distance to this galaxy using a value for the Hubble constant of H₀ = 68 km s^–1 $\,$ Mpc^–1.
17M.3.SL.TZ2.12c.i:
Determine the distance to the galaxy in Mpc.
18M.3.SL.TZ1.12b:
Estimate, in Mpc, the distance between the galaxy and the Earth.
19M.3.SL.TZ2.14aii:
A line in the hydrogen spectrum when measured on Earth has a wavelength of 486 nm. Calculate, in nm, the wavelength of the same hydrogen line when observed in the galaxy’s emission spectrum.
21N.1.SL.TZ0.30: Which is correct for a black-body radiator? A. The power it emits from a unit surface area...

Hide related questions

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

Option D: Astrophysics