| Date | May 2018 | Marks available | 3 | Reference code | 18M.3.HL.TZ2.13 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Comment | Question number | 13 | Adapted from | N/A |
Question
The diagram represents a simple optical astronomical reflecting telescope with the path of some light rays shown.
It is proposed to build an array of radio telescopes such that the maximum distance between them is 3800 km. The array will operate at a wavelength of 2.1 cm.
Comment on whether it is possible to build an optical telescope operating at 580 nm that is to have the same resolution as the array.
Markscheme
«use of \(\frac{{1.22\lambda }}{d}\) to get» resolution of 6.7 × 10–9 «rad»
\(\frac{{5.8 \times {{10}^{ - 7}}}}{{6.7 \times {{10}^{ - 9}}}}\) = 87 «m»
some reference to difficulty in making optical mirrors/lenses of this size
Allow \(\frac{{5.8 \times {{10}^{ - 7}}}}{{5.5 \times {{10}^{ - 9}}}}\) = 105 «m»
[3 marks]
Examiners report
[N/A]
