You are examining a prepared slide with the 40x objective in place over the microscope. you rotate the 100x objective over the slide. when you look into the eyepiece, your specimen is gone. what happened?

A microscope is an instrument in biology that helps in viewing specimens which cannot be seen through the naked eyes. Objective lenses of microscopes (10x, 40x and 100x) help in magnifying a specimen.

When a specimen being observed with 40x objective lens in a microscope is rotated to 100x objective of the microscope, the specimen is lost because of the following reasons-

1. 100x objective is called the oil immersion objective which needs a special oil for observing specimens under it. Thus, specimens cannot be observed without the oil.

2. There are chances that the slide may be crushed due to this rotation and the specimen is damaged. Hence, using coarse adjustment knob of the microscope, the 40x objective has to be lifted away form the slide to some distance. A drop of oil should be placed on the slide and slowly the 100x objective should be brought into focus by using the fine adjustment knob of the microscope.