Which of the following statements is/are correct?

(a) Electromagnetic waves have different speeds in different mediums.

(b) Sounds have different speeds in different mediums.

Concept:

Electromagnetic wave:

• It can also be said that electromagnetic waves are the composition of oscillating electric and magnetic fields.
• Electromagnetic waves are shown by a sinusoidal graph.
• It consists of time-varying electric and magnetic fields which are perpendicular to each other and are also perpendicular to the direction of propagation of waves.
• The direction of propagation of the electromagnetic waves is given by the Poynting vector.
• Poynting vector, \(\vec P=\vec E\times \vec B\)

• Electromagnetic waves travel at c = 3.0×10⁸ m/s in a vacuum but slow down when they pass through a medium because the material has a different value for the permittivity and/or permeability due to the interaction of the wave with the atoms of the material.
• The relation between the magnitude of the electric field and the magnetic field is given as E0 = B0 c

Sound wave:

• A sound is a vibration that propagates through a medium in the form of a mechanical wave.
• The medium in which it propagates can either be a solid, a liquid, or a gas.
• Sound travels fastest in solids, relatively slower in liquids, and slowest in gases.

Explanation:

• Electromagnetic waves have different speeds in different mediums because the material has a different value for the permittivity and/or permeability due to the interaction of the wave with the atoms of the material.
• Sounds have different speeds in different mediums.

Hence, both given statements are true.