Reflection of Light

We ‘see’ a lot of things around us on a daily basis. But how are we able to do so? You might answer saying it is because of our eyes. Isn’t it? And you aren’t wrong. But is it just the eyes? What about the light bounced back from the things around us and enabling us to see things better? What is this phenomenon? It’s because of ‘Reflection of Light’. Let us study more about it below.

What is Reflection of Light?

When a ray of light falls on any object (polished, smooth, shiny object), light from that object bounces back those rays of light to our eyes and this is known as “Reflection” or “Reflection of Light”.
This phenomenon is what enables us to look at the world around us based. Before, after and during reflection light travels in a straight line. For example, twinkling of stars or light reflected by a mirror.

Laws of Reflection

In theÂ diagram given above, the ray of light that approaches the mirror is known as “Incident Ray”. The ray that leaves the mirror is known as “Reflected Ray”.
At the point of incidence where the incident ray strikes the mirror, a perpendicular line is drawn known as the “Normal”. This normal is what divides the incident ray and the reflected ray equally and gives us the “Angle of Incidence” (Qi) and “Angle of Reflection” (Qr).

Hence the above information gives us the “Laws of Reflection of Light”Â which state that :

a. The angle of incidence is equal to the angle of reflection.
b. The incident ray, the normal and the reflected ray, all lie in the same plane.

Types of Reflection:

There are two types of reflection :

a. Specular/ Regular reflection
b. Diffused/ Irregular reflection

a. Specular/ Regular reflection:

Specular/Regular reflection is the mirror-like reflection of rays of light. In such a type of reflection, the rays of light that are reflected from a smooth and shiny object such as a mirror, are reflected at a definitive angle and each incident ray which is reflected along with the reflected ray has the same angle to the normal as the incident ray.Â Thus, this type of phenomena causes the formation of an image.

b. Diffused/ Irregular Reflection:

Diffused/Irregular reflection is a non-mirror-like reflection of light. In such a type of reflection rays of light that hit an irregular object with a rough surface, are reflected back and scatter in all directions.Â Here, the incident ray which is reflected along with reflected ray doesn’t have the same angle to the normal as the incident ray.
Thus, this type of reflection doesn’t form an image.

Image Formation by Plane Parallel Mirrors

As shown in the figure, infinite images are formed when an object placed is placed between two parallel plane mirrors.

Consider an object placed in between the mirrors and we can actually see the image, in this case, the number of images would range from 1 to X (X being a very large number depending on your position relative to the mirror and object, and X not infinity).

Angle between mirrors =Â Î¸=O

Hence,

Number of images formed =Â 360/Î¸

So, in case of parallel mirrors, we get infinite images.

Solved Example For You

Q.Â Which of the following phenomenon has two angles that are equal to each other?

a. Reflection

b. Refraction

c. Diffraction

d. None of the above

Sol: a. Reflection

According to Snell’s law of reflection, the angle of reflection with normal is equal to the angle of incidence with that normal and all these lies in the same plane.

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