Question

The statement that is true about ‘light’ is:
A) Requires a material medium to travel from one place to another
B) Does not require a material medium
C) Light has mass but its negligible
D) Light waves are longitudinal

Answer 1

Hint: You can solve the asked question by going through each of the given four statements, and checking them right then and there. Obviously, light doesn’t need any medium to travel, otherwise, the value of $c$ , i.e. the speed of light in vacuum would have no meaning.

Complete step by step solution:
As described in the hint section of the solution to the question, we will approach the solution the same way. We will go through each of the given statements and will discuss whether it is true or not for light.
Let us first check statement A:
It states that Light required a medium to travel from one place to another. We can clearly see that this statement is clearly false since if it was the case, there would be no meaning to the universal constant $c$ , which is nothing but the speed of light in vacuum and is numerically equal to $3 \times {10^8}\,m/s$ . Since vacuum is nothing but the absence of everything, and light still travels through it, it clearly means that light doesn’t need any medium in particular for it to travel from one place to another.
Now, let us check for the statement C:
Statement C states that “Light has mass but it’s negligible”.
This statement is completely false as light is made up of photons which are massless particles. If light is made up of massless particles, it can’t have any mass itself.
Now we will check the statement D which states that “Light waves are longitudinal”.
This is clearly a false statement as light waves are not longitudinal but transverse waves, on the other hand, sound waves are longitudinal waves.
Statement B states that “Light does not require a material medium” which means that light does not require a medium to travel from one place to another, we have already discussed how statement A is false because light doesn’t need any medium to travel.

Hence, we can say that statement B is true and hence, the correct option is option (B).

Note: Many students can get confused and tick option D as correct. Longitudinal waves are those waves in which particles get displaced or displaced along the direction of propagation of the wave. While in transverse waves, particles get displaced or disturb in direction perpendicular to the direction of propagation of the wave.