Question

State whether given statement is true or false
Light waves require no medium for their propagation.
(A) True
(B) False

Answer 1

Hint: A wave transmits information or energy from one point to another in the form of signals, but no material object makes this journey. Depending on the requirement on medium for propagation we have two types of wave namely Mechanical and Non-mechanical waves. Light waves are only non- mechanical waves in nature.

Complete step by step solution:
A wave is a disturbance in a medium that carries energy without a net movement of particles. It may take the form of elastic deformation, a variation of pressure, electric or magnetic intensity or temperature.
Now if a wave requires medium for propagation then it is mechanical in nature. Examples of such waves are sound waves.
If waves do not require medium for propagation then the wave is non-mechanical in nature. Electromagnetic waves are only non-mechanical waves.
Now, in the case of mechanical waves, the material medium serves two purposes—it provides a restoring force and it provides inertia. In the case of EM waves, the magnetic induction provides these services for the electric field and electric induction provides these services for the magnetic field. Unlike mechanical waves, EM waves are self-propagating.
All electromagnetic waves travel through a vacuum at the same speed is:
$c = \dfrac{1}{{\sqrt {{\mu _o}{\varepsilon _o}} }}$
Where,
${\mu _o}$ Is called absolute permeability. Its value is $1.257 \times {10^{ - 6}}Tm{A^{ - 1}}$
${\varepsilon _o}$ Is called absolute permittivity. Its value is $8.854 \times {10^{ - 12}}{C^2}{N^{ - 1}}{m^{ - 2}}$
And $c$ is the speed of light in vacuum.
 The speed of light in vacuum is nearly equal to $3 \times {10^8}m{s^{ - 1}}$
 Hence it is true that the light waves does not require a medium to propagate.

Note: Electromagnetic waves do not have "charge" as they result from changing electric and magnetic fields, and there is no transfer of charge here; the oscillation of electric and magnetic "fields" that are not defined as positive or negative.