Why is the aperture of objective lens of a telescope taken large ?

The aperture of the objective lens of a telescope is made large so as to

Why the aperture of objective lens of the microscope is small and that of telescope is large ?

Why is power of objective lens of a telescope kept as small as possible ?

(a) Draw a labelled ray diagram to obtain the real image formed by an astronomical telescope is normal adjustment position. Define its magnifying power. (b) You are given three lenses of power 0.5 D , 4D and 10D to design a telescope. (i) Which lenses should be used as objective and eyepiece? Justify your answer. (ii) Why is the aperture of the objective preferred to be large ?

If the aperture of the objective of a telescope is decreased, then its resolving power

The diameter of the objective lens of a telescope is 5.0m and wavelength of light is 6000 Å . The limit of resolution of this telescope will be

A binary star system is observed using a telescope. The angular separation between both the stars is 5 xx 10^(-6) radians. Calculate the aperture of objective of the telescope if light of wavelength 5,500 Å is used.