The focal length of the field lens (which is an achromatic combination of two lenses) of telescope is |
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a) |
30 |
b) |
30 |
c) |
45 |
d) |
15 |
The focal length of the field lens (which is an achromatic combination of two lenses) of telescope is |
|||||||
a) |
30 |
b) |
30 |
c) |
45 |
d) |
15 |
(b) For achromatic combination Solving above equations we get |