Chapter 17.1, Problem 9SSC

To determine

To explain:The application of law of reflection to diffuse reflection.

Answer to Problem 9SSC

In case of diffuse reflection, the law of reflection is applied to each individual light ray incident on the rough irregular surface.

Explanation of Solution

Introduction:

Consider a light ray falls on a plane surface; the incidence angle made by light ray with the normal to the surface is same as reflectance angle made by the light ray with the normal to the surface. This is known as law of reflection.In case of a diffuse reflection, the parallel light rays are incident on the irregular rough surface; it gets diffused in different direction. The reflected rays of light are non-parallel.

Consider parallel light rays falls on the rough irregular surface, it gets diffused in different direction. Such type of reflection is referred to as diffused-reflection. The ray diagram for the diffused reflection is shown below.

  

Figure 1

Consider Figure 1. The incident rays of light are parallel to each other.The angle formed by the each incident light ray with the normal to the surface is denoted by ${\theta }_{\text{i}}$ and the angle formed by the each reflected light ray with the normal to the surface is denoted by ${\theta }_{\text{r}}$ .The reflected rays are non-parallel, but the incident angle $\left({\theta }_{\text{i}}\right)$ for each light ray is same as corresponding reflection angle $\left({\theta }_{\text{r}}\right)$ .Hence, in case of diffuse reflection, the law of reflection is applied to each individual light ray incident on the rough irregular surface.

Conclusion:

Thus, in case of diffuse reflection, the law of reflection is applied to each individual light ray incident on the rough irregular surface.