Question

derive an expression for magnifying power of simple microscope.obtain its minimum and maximum values in term of its focal length​

Answer 1

The magnifying power of the simple microscope is the ratio of the angle subtended at the eye by the image when seen through the lens to the angle subtended at the eye by object on the naked eye.

Let:

M is the magnifying power, f is the focal length and d is the least distance of distinct vision so,

M = 1+ $\frac{d}{f}$

Now, M will be maximum if focal length will be zero and M will be minimum when focal length will be infinity.

Answer 2

Expression for magnifying power of simple microscope:

• The “magnifying power” of the simple microscope is in the ratio between the “angle which subtended by the image that is seen through the lens and the angle at which subtended by the object at “unaided eye”, when both of them are placed in a least distance of the distinct vision that is denoted by the M.”

The “magnifying power of simple microscope” is  

                                 $M=1+\frac{D}{F}$

with F being “the focal length” and D being the “least distance of distinct vision”.