Physics is a very interesting subject and the 12th physics is very important and useful and gives knowledge. Actually it’s a very easy subject if we understand. Physics is just a natural science; it is based on many experiments, mathematical analysis and measurements. We learn this **physics subject** for a purpose of finding quantitative physical laws.

Many of the optical devices and instruments had been designed by using **reflecting and refracting** properties of lenses, mirrors and prisms. Periscope, telescope, microscope etc are some of the examples of optical devices and instruments which are in common use. However, we know that our eye is the most important optical device. Now here we are going to discuss the principles of microscope and telescope in **ray optics**.

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**The microscope**

A simple microscope is a converging lense of a small focal length. In case we want to use such a microscope, the lens should be placed near the object, and the eye should be closer to the lens of the other side. The result will be we get an erect, magnified and virtual image of the object. If the object is placed at the distance of focal length(f) and if the image is at infinity. If the object distance is slightly less than the focal length of the lens, the image is virtual and closer than infinity.

The linear magnification for the image formed at the near point by a simple microscope can be obtained by using the relation is

m=v=v{1-1}={1-v}

u { v f} { f }

Now according to sign convention, v is negative, and is equal in magnitude. Thus, the magnification is

m={1+D}

{ f }

**Conclusion: **

The **physics subject is very important in class** 12 and also it will be very useful in higher studies this ray optics topic. In our higher studies it is very essential to learn this topic. Everyone should learn this ray optics topic.