Laws and types of Reflection – All about Reflection

Laws and Types of Reflection

 Key Concepts

• Reflection of light
• Terms related to the reflection of light
• Laws of reflection
• Incident ray, Reflected ray, Normal
• Types of reflection

Introduction

It is known that the phenomenon of bouncing back of light when it falls on a surface is called the reflection of light. Whenever light reflects off a surface, it follows two rules/laws irrespective of the type of surface it reflects off. There are two types of reflections of light based on the type of surface it reflects off. We will be looking at all these concepts in detail in this section. 

Explanation

Terms related to reflection of light: 

There are some terms that are used universally to discuss the reflection of light when it falls on a surface. They are as follows: 

1. The surface that reflects light is called a reflecting surface. 

2. A ray of light that hits the reflecting surface is called an incident ray. 

3. The incident ray after reflecting off the surface is called the reflected ray. 

4. The point at which the incident hits the reflecting surface is called the point of incidence. 

5. An imaginary line is always drawn perpendicular to the reflecting surface at the point of incidence, called the normal. 

6. The angle made by the incident ray with the normal is called the angle of incidence (i). 

7. The angle made by the reflected ray with the normal is called the angle of reflection (r). 

Laws of reflection: 

Light follows two laws whenever it reflects off any surface. They are as follows: 

1. The incident ray, the reflected ray and the normal at the point of incidence all lie on the same plane. 

2. The angle of incidence is equal to the angle of reflection.  

                                     i = r 

 

Types of reflection: 

Reflection of light occurs in two ways depending upon the nature of the surface by which it is getting reflected. They are as follows: 

Regular reflection: 

• When a surface is highly smooth, like in the case of a mirror, then the image formed after reflection is sharp and clear. 

• This type of reflection of light that takes place when it reflects off a highly smooth surface is called regular reflection. 
• When a beam of light incidents on the surface of a mirror, the reflected rays are also parallel to each other. This is the reason behind sharp and clear images. 

Diffused (Irregular) reflection: 

When a surface is even slightly rough, like in the case of a wooden table, then the image is either not formed or is blurred if it forms. 

This type of reflection of light that takes place when it reflects off a rough surface is called diffused or irregular reflection. 

When a beam of light incidents on the surface of a mirror, the reflected rays are not parallel to each other but randomly directed. This is the reason behind blurred or no images. 

Summary

1. The incident ray, the reflected ray and the normal at the point of incidence, all lie
   on the same plane.
2. The angle of incidence is equal to the angle of reflection i.e., i=r.
3. When a surface is highly smooth, the image formed after reflection is sharp and
   clear. This type of reflection of light is called regular reflection.
4. In regular reflection, when a beam of light incidents on the surface of a mirror, the
   reflected rays are also parallel to each other. This is the reason behind sharp and clear images.
5. When a surface is even slightly rough then the image is either not formed or is
   blurred if it forms. This type of reflection of light is called diffused or irregular reflection.
6. In diffused reflection, when a beam of light incidents on the surface of a mirror, the
   reflected rays are not parallel to each other but are randomly directed. This is the reason behind blurred or no images.
7. Both regular and diffused reflections hold the laws of reflection.