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Question
With the help of a ray diagram explain the working of a reflecting telescope.
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Solution
Parallel light beams from an infinite distance are incident on two concave objective mirrors at first. They are incident on a secondary convex mirror after reflection. At F, a virtual image is produced. The rays meet at a point after reflection by the convex mirrors to generate a true image, which is perceived through the eyepiece.
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Useful Constants & Relations:
| 1 | Charge of a proton | e | 1.6 × 10-19 C |
| 2 | Speed of light in vacuum | c | 3 × 108 ms-1 |
| 1 u = 931 MeV | |||
Assertion: An astronomical telescope has an objective lens having large focal length.
Reason: Magnifying power of an astronomical telescope varies directly with focal length of the objective lens.
