| Date | May 2014 | Marks available | 3 | Reference code | 14M.3.HL.TZ1.19 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 19 | Adapted from | N/A |
Question
This question is about evidence that supports general relativity.
The astronomical photograph taken from Earth shows four separate images of a single distant quasar that appear to surround a galaxy. The galaxy is closer to Earth than the quasar.
Outline how one image of the quasar is formed. You may draw on the diagram below that shows the arrangement of the Earth, the galaxy and the quasar to support your answer.
Markscheme
mention of gravitational lensing;
galaxy has a very large mass/gravitational field;
this field/mass bends the direction of light emitted by the quasar;
spacetime is distorted by this field/mass;
Award [1 max] for a diagram showing only a curve joining the quasar and the Earth.
Award [3] for an annotated diagram.
Examiners report
Many well prepared candidates realized that the light is bent. However, “outline” requires a brief account or summary, so a more detailed answer was required here. Information such as the galaxy has very large mass should be mentioned, at least implicitly.
