Question

Incident ray is the ray of light striking a surface.
A. True
B. False

Answer 1

A narrow stream of radiation that propagates in a rectilinear motion is called a light ray. A light ray is often represented by a line in the direction in which light is traveling. As light experiences different mediums, it shows different phenomena such as reflection, refraction, dispersion, etc. Different types of rays are used to represent the path of light in different mediums.

Complete step by step solution:
The rays of light that get incident on a smooth surface at a certain angle with the surface are called incident rays. As light travels in a medium, it strikes a surface and a part of the incident rays get bounced back in the same medium from which it came. This phenomenon of light is called reflection. The rays that get bounced back are called reflected rays. The point at which the light meets the surface is called the point of incidence. There are certain angles made by the incident ray, surface normal, and the reflected ray. The angle subtended by the incident ray and the surface normal is called the angle of incidence and the angle subtended by the surface normal and the reflected ray is called the angle of reflection.
The laws of reflection are as follows:
The incident ray, the reflected ray and the normal all coexist on the same plane and this plane is called the plane of incidence.
According to the law of reflection, the value of the angle of reflection and the angle of incidence are equal.
Similarly, when the incident ray meets the boundary of the two different mediums, some part of it gets refracted as they travel in a different medium from which it came. The refracted ray bends toward the normal as it travels in the second medium. Such a phenomenon is called refraction. The angle subtended by the refracted ray and the normal is called the angle of refraction.
The law of refraction is:
The incident ray, the refracted ray, and the normal all are on the same plane. The point at which all these rays meet is called the point of incidence.
An invariable quantity is used to define the ratio of the sine of the angle of incidence to the sine of the angle of refraction i.e. the value of the ratio remains constant with time. This constant term is known as the refractive index. Mathematically, it is represented as:
$\dfrac{{\sin \,i}}{{\sin \,r}} = {n_{21}}$ ……$(1)$
Where $i =$ angle of incidence
$r =$ angle of refraction
${n_{21}} =$ refractive index
The equation $(1)$ is also known as Snell’s Law.
Therefore, option (A) is the correct answer.

Note: Light has dual nature. This means that it acts like a wave as well as a particle. Reflection and refraction are phenomena due to the wave nature of light and the Photoelectric Effect and Compton Effect are due to the particle nature of the light.
The laws of reflection are applicable only when the incident light meets a smooth surface. This type of reflection where an incident ray strikes a smooth surface is called specular reflection.