| Date | May 2011 | Marks available | 1 | Reference code | 11M.3.SL.TZ1.15 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | State | Question number | 15 | Adapted from | N/A |
Question
This question is about cosmology.
State how the observed red-shift of many galaxies is explained.
[1]
a.
Explain how the cosmic microwave background (CMB) radiation is consistent with the Big Bang model.
[2]
b.
Calculate the temperature of the universe when the peak wavelength of the CMB was equal to the wavelength of red light (7.0×10−7m).
[2]
c.
Markscheme
the universe is expanding / many galaxies are moving away from us;
a.
the CMBR fills all of space / is uniform / is distributed equally, consistent with an “explosion” (at start of universe);
the temperature of the radiation (2.7 K) is consistent with cooling due to expansion/redshift;
b.
\({\lambda _{\max }} = \frac{{2.9 \times 10 - 3}}{T} \Rightarrow T = \frac{{2.9 \times {{10}^{ - 3}}}}{{7.0 \times {{10}^{ - 7}}}}\);
T = 4100K;
c.
Examiners report
[N/A]
a.
[N/A]
b.
[N/A]
c.
