## Seven Colors in a Rainbow and absent colors

People have a joy in seeing Rainbow in the fresh sky after a rainstorm. It looks very pleasing to our eyes. I use to find rainbow in the sky every time after the rainfall. But, what causes a Rainbow? Do you know that? I read in Physics book that a Rainbow has seven different colors. … Read more

## Focal length of a concave mirror – theory and experiment

Spherical mirror has two types – Concave mirror and Convex mirror. In this article, we’re going to discuss the focal length of a concave mirror. Though, the focal length of both types of mirrors has the same definition and units, but the signs of focal length are different for these two mirrors. Here, we have … Read more

## How to find refractive index of a material?

In another article, we discussed the refractive index of a material and most of the facts related to refractive index. The value of the index of refraction is different for different materials. So, it is better to a rule to calculate the refractive index of different materials. In this article, we’re going to discuss how … Read more

## Refractive index – definition, formula, dependence, List

If you emerge a straight pencil into a glass of water, you can see the part of the pencil inside the water is bent. The pencil does not bend. It appears to be bent because the light bends while passing from one medium to another medium. Now, the question is, why does light bend when … Read more