| Date | May 2017 | Marks available | 3 | Reference code | 17M.3.SL.TZ2.9 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 2 |
| Command term | Estimate | Question number | 9 | Adapted from | N/A |
Question
Two converging lenses placed a distance 90 cm apart are used as a simple astronomical refracting telescope at normal adjustment. The angular magnification of this arrangement is 17.
Determine the focal length of each lens.
The telescope is used to form an image of the Moon. The angle subtended by the image of the Moon at the eyepiece is 0.16 rad. The distance to the Moon is 3.8 x 108 m. Estimate the diameter of the Moon.
State two advantages of the use of satellite-borne telescopes compared to Earth-based telescopes.
Markscheme
states fo + fe = 90 AND \(\frac{{{f_{\text{o}}}}}{{{f_{\text{e}}}}} = 17\)
solves to give fo = 85 AND fe = 5 «cm»
Both needed.
Both needed.
[2 marks]
angle subtended by Moon is \(\frac{{0.16}}{{17}} = 0.0094\) «rad»
\(0.0094 = \frac{D}{{3.8 \times {{10}^8}}}\)
D = 3.6 x 106 «m»
Allow ECF from MP1.
Allow [2] for an answer of 6.1 x 107 «m» if the factor of 17 is missing in MP1.
[3 marks]
operation day and night
operation at all wavelengths/no atmospheric absorption
operation without atmospheric turbulence/light pollution
Accept any other sensible advantages.
[2 marks]
