Section-C: Comprehension Type
The invention of the compound microscope by Jansen in the late 1500’s truly revolutionized the world of science, particularly the field of cellular and molecular biology. The discovery of the cell as fundamental unit of living organisms and the insight into the bacterial world are two of the contributions of this instrument to science.
It is unseemly that such a relatively simplistic apparatus took generations to be developed. Its main components are two convex lenses: one acts as the main magnifying lens and is referred to as the objective, and another lens called the eyepiece. The two lenses act independently of each other when bending light rays. The actual lens set-up is depicted in figure. Light from the object (O) first passes through the objective and an enlarged, inverted first image is formed. The eyepiece then magnifies this image. Usually the magnification of the eyepiece is fixed (either X10 or X15) and three rotating objective lenses are used: X10, X40 and X60. The most recent development in microscope technology is the electron microscope which uses a beam of electrons instead of light. Photographic film must be used otherwise no image would be formed on the retina. This microscope has a resolution about a hundred times that of the light microscop
The magnification of the eyepiece of a compound microscope is X15. The image height is 25 mm and the magnification of the objective is X40. What is the object height?