Introduction
Light is an essential part of our lives. Light is also an important form of energy that we depend on every day. Without it, we couldn’t see the world around us. But how does Light reach us? And how does it affect the way we see our world? So here we are going to discuss the topic Light.
WHAT IS LIGHT?
Light is that thing due to which we can see an object.
The human eye (Retina) detect electromagnetic waves within a small range (400 nm to 700 nm) of the electromagnetic spectrum is called light.
Q> Can we see light?
Ans> No, we see the only object which is on the way of light.
Q> What else is needed for vision?
Ans> Light, Object and Eye
Q> But will all finite size objects be visible if there is a light and an eye to perceive it?
Ans> No, perfectly transparent glass and perfectly reflecting mirror will not be able to see, Because the object doesn’t alter the incident light in any way i.e it doesn’t leave its signature on the incident ray for the eye. Simply alter means partially absorb of light and/ or scattering of light by an object.
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There are two things that we can easily mention about light from common experience. First, it travels with enormous speed () and second that it travels in a straight path.
the speed of light in a vacuum is the highest speed attainable in nature.
A single path from one point to another along a straight line is called a ray of light and bundle of such rays forms a beam of light.
LIGHT IS A WAVE OR PARTICLE!
The question of whether light is a wave or particle has a very interesting and long history.
According to Newton, light is a collection of particles called corpuscles that are emitted by the source, and these corpuscles travel is a straight path. This concept is known as the particle nature of light. Newton could explain the laws of reflection and refraction of light on the basis of the particle nature of light. But many optical phenomena could not be explained by the particle nature of light.
The Dutch physicist Christian Huygens, who was a contemporary of Newton, suggested that light may be a wave phenomenon, and due to small wavelength, it travels in a straight path.
But due to the double-slit experiment of Thomas Young and experiment on diffraction of light of Augustin Fresnel, convincingly established that light is a wave phenomenon.
But the drama was not yet over. The climax came when the wave theory of light failed to explain the phenomena of the photoelectric effect.
But the question was still what the light is? wave or particle.
Ans:- It can behave as particle as well as wave( dual nature) depending on its interaction with the surrounding. Later it was found that even the well-established particles such as electrons also have a dual nature.