WHAT IS TIME ? Einstein had once said, "Time is just an illusion". Perhaps it is true that time really does not exist for the universe. After all, we humans are the ones who made it up. THE HISTORY OF TIME A long time ago(sometime before the 1500 B.C.), the sundial was invented in ancient Egypt and the measurement of time began. But back then, time was not measured in the same way as it is measured in the present. The concept of minutes, seconds, and hours didn't exist at that time. In the past, the unit of time was the period of daylight I had recently read somewhere that maybe time was invented by clock companies to sell more clocks. Are clocks all that time is associated with? Is there nothing else about time other than minute, second, and hour hands? Of course there is. So let us start expanding our knowledge on time. We have all obviously known since our childhood what time means. But what would you say if I ask you to explain it to me? How would you p...
You must have heard of reflection of light. It's when a ray of light bounces back from a surface. When a light ray hits a mirror, it bounces back with the same angle as the angle with which it hit the mirror. The angle of incidence is always equal to the angle of reflection But what if instead of a mirror, there is a transparent surface? In such cases, the light ray goes through the surface, and undergoes refraction. What is refraction? Refraction is the bending of light when it goes from one medium to another. This happens because the speed of light changes across two different media. When a ray of light is perpendicular to the normal, it travels to the other medium without bending. The ray of light only bends when it goes obliquely from one medium to another. This bending of light depends on the medium through which light is travelling. Optical Density • Rarer medium: The medium through which the speed of light is more is an optically rarer medium. • Denser medium: The medium...