Nancy Vishwakarma

“Things seen under a greater angle appear greater ,and more under a lesser angle less, while more under equal angle appear equal.” observed by Euclid(Greek Mathematician).The word optics is derived from the Greek word ‘Optikos’ meaning ‘appearance or look’. Around 1st century BC, the Vishnu Purana refers to the sunlight as ‘seven rays of the sun. ’The application of optics had been used by the Indians since ancient times. Optics exist in almost every day of our life. Let’s ponder! How optics affect our daily life with mirrors and lenses? Of course, Through reflection. The invention of mirrors is the greatest contribution to humankind. All thanks to Italy for inventing mirrors. We use the mirror while shaving or dressing for a party or while cleansing the face etc. There are numerous uses of concave mirrors in daily life. It is used as a torchlight to reflect the light rays, it is used during shaving to get an erect and enlarged image of the place. They are mostly used to focus light. A convex mirror is used in automobiles such as scooters, trucks, and buses as a rearview mirror to see the traffic behind the vehicle. The reason for that is that a convex mirror has a much wider field view and the image formed are smaller and erect. What about refraction? If you own a DSLR then it’s pretty easy for you to understand. Well, the camera lens which we use on our DSLR or even a camera lens in our smartphone camera is spherical in shape. You all know the importance of a camera lens to take a good picture. You must have used a microscope in the biology class, biology class is incomplete without a microscope.

My friend wears eyeglasses. They are the first thing she put on and the last thing she takes off every day. The lens of eyeglasses works because of refraction even all lenses.

Have you ever heard of optical fibres?

Nowadays, optical fibres are extensively used for transmitting audio and video signals through long distances. That’s exactly how the TV cable works. More scientifically, it works on the principle of total internal reflection.

Do you know what’s Doppler’s effect?

The best example of the Doppler’s Effect is one of the ambulance passing by. Let me explain. The frequency of the siren increases as it comes near you, and then diminishes as it passes away. But if you ask the person inside the ambulance, the frequency of the sound remains the same.

Do you bother using sunglasses?

The answer is yes, you should wear sunglasses while going out in sun. The polaroids are used to control the intensity, in sunglasses, window panes, etc.

If you are acquainted with the term diffraction?

Well! You have definitely seen the rays coming through clouds someday or the bending of light around the corners of the door and the windows. They both are examples of light diffraction.

In your life you must have used an optical instrument sometime. Can you recall any?

Periscope, kaleidoscope, binoculars, telescopes, microscopes are some examples of optical devices and instruments that are in common use.

Can you think of some natural phenomena related to optics?

Eye itself has a lens and is a natural optical device. The interplay of light with things around us gives rise to several beautiful phenomena such as rainbow(dispersion of sunlight) and the red-hue at sunrise and sunset.

Optics have a wide variety of applications in our daily life. We use mirrors(plane mirror),shaving mirror(concave,)rear view mirrors(convex),cameras(refraction through spherical mirrors),optical fibers(total internal refraction),ambulance’s siren(Doppler’s effect),sunglasses(polaroids),bending of light rays around the corners(diffraction),optical instruments and some natural optical phenomena.

I look at you, you look at me, I raise my right, you raise your left what am I? Guess.

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