Question

Modern telescopes often use a concave mirror rather than a lens for the objective primarily because:

Options

• A mirror magnifies the image more than a lens

• There is no chromatic aberration in a mirror

• A mirror can form erect images while a lens cannot

• A mirror requires a shorter focal length than any lens

Answer 1

Telescopes with mirror objectives are called reflecting telescopes. A key advantage is that there is no chromatic aberration in a mirror, since reflection does not depend on wavelength, unlike refraction through lenses.