Question
Physics Question on Ray optics and optical instruments
In a reflecting astronomical telescope, if the objective (a spherical mirror) is replaced by a parabolic mirror of the same focal length and aperture, then
A
the telescope will gather more light
B
spherical aberration will be absent
C
the larger image will be obtained
D
the final image will be erect
Answer
spherical aberration will be absent
Explanation
Solution
When a spherical objective mirror is replaced by a parabolic mirror, it eliminates the spherical aberration.