Laws of reflection

It's only because of light we are able to see this world around us

So what happens is, when light falls on the surface of an object, it returns back or reflects the light

This reflected light falls in our eyes, and this is how we see the objects

Here, bouncing off light when it hits an object is called Reflection

But while reflecting from mirrors, Light follows few laws. Which we will discuss them in Laws of Reflection

The first law of reflection states that the angle of incidence = Angle of reflection

The angle of Incidence is the angle that an incident ray makes with a perpendicular to the surface at the point where light falls

The angle of Refraction is the angle that a reflected ray makes with a perpendicular to the surface at the point where light bounces off

The second law of reflection states that the incident ray, the reflected ray and the normal to the surface lie in the same plane

The plane contains the incident rays, reflected rays and the normal

Let us try to understand more about the laws of reflection by solving a problem

Let's consider an incident ray and the reflected ray falling on a mirror are perpendicular to each other

Then, we have to find the angle of incidence

Let's construct the general diagram showing the incident ray, reflected ray and the normal

We have already considered the second law of reflection that all the rays are in the same plane while constructing this figure,

But, we have been told in the problem that the incident ray and the reflected ray are perpendicular to each other

Hence, we can say that $i+r$ = 90°

But, from the first law of reflection, we have $i=r$

Hence, $i+i$ = 90°

$2i$ = 90° $i$ = 45°

Hence, we get the angle of incidence = 45°

This is the final diagram showing the angle of incidence and the angle of reflection

Revision

We have discussed the Laws of Reflection

$1^{st}lawofreflection$ says that the angle of incidence and reflection are equal

$2^{nd}lawofreflection$ says that the incident reflected and normal rays lie in the same plane

Given in the problem, the incident ray and the reflected ray are perpendicular to each other. Hence, $i+r$ =90°. We have to find $i$

But we know $i=r$ $i+i$ = 90° $⟹$ $2i$ = 90° $⟹$ $i$ = 45°. Hence the Angle of Incidence = 45°

The End