Question

When are concave and plane mirror used in compound microscope?

Answer 1

The eyepiece with different magnification (5-20 times). It has field-lens towards the object and eye-lens close to the observer’s eye. The objectives are generally with three different magnifications viz., low power (10X), high power (40-45X) and oil-immersion (90-100X).
The mirror reflects light which is transmitted through the object for observing it. The mirror has two planes, one concave and the other plane.

When natural light is available the plane mirror may be used for reflection of light because concave mirror would form window images. However, with artificial illumination, the concave mirror is necessary for higher magnifications whereas for lower, the plane mirror may be used.