How does a Telescope works?

Well, the telescope is a very important thing in astronomy. By this only we can see other planets, stars, comets, asteroids, and other celestial bodies. So it is important to know how the telescope works. In today's session, we will be learning about this only. So, let's get started...

Telescopes are made up of two lenses (two biconvex lenses) one called the objective and the other, the eyepiece. The difference between these two is that the objective has a larger focal length while the eyepiece has a smaller focal length. What is this focal length? Well, the focal length is the distance from a lens or mirror to the focal point. Now, what is this focal point? The focal point is the point where the parallel rays of light meet or converge. 

Ok, let's get back to our topic. The lens receives parallel rays and then these parallel rays are focused by the objective and it forms a real inverted and small image. The concept is that the eyepiece is placed in such a way that the image is formed at the focus of the eyepiece. Now, what's this focus? The focus is the point at which rays of light, heat, or other radiation (here light) meet after being refracted or reflected. Therefore, the eyepiece forms a virtual inverted and magnified image of a particular image formed at the focus.  

This is how the telescope works: