Question

What do you mean by “Rectilinear propagation of light”?
a.)Light travels in a straight line
b.)Light travels in a curved path
c.)Light exhibits dual nature of particle and wave
d.)Light gets deviated when it moves in another medium

Answer 1

Hint: Understand the meaning of the terms rectilinear and propagation to understand their combined meaning.

Complete step by step answer:
Rectilinear refers to the straight line and propagation means action or process of spreading. Thus, the word rectilinear propagation of light means that light travels in a straight line.

Light always moves in a straight line. It deviates from its path in the following situations:
When light hits an obstacle, it changes its path in the same media. This phenomenon is known as reflection.
When light travels from one medium to another then it changes its path in another medium. This phenomenon is called refraction.

Few examples of rectilinear propagation of light are:
-Sunrays enter a room in a straight line.
-Torch always projects light in a straight line.
-The projector always projects light in a straight line.
-The headlights of cars always project light in a straight line.

Additional information:
Rectilinear propagation of light was discovered by Euclid’s Catoptrics. It has a wave nature.
This phenomenon is used for:
-formation of shadows
-Formation of day and night.

Note: Light does not travel in a curved path thus, option B is incorrect. While option C that is light exhibits dual nature of particle and wave and option D, that light gets deviated when it moves in another medium are true but they do not mean the same as “Rectilinear propagation of light”. Thus, the correct answer is option A.