Question

Mechanical waves travel as disturbances in a physical medium. How do electromagnetic waves travel?

Answer 1

Electromagnetic or EM waves are waves that are generated as a result of vibrations (or say, oscillations) between a time varying Electric Field and a time varying Magnetic field. The direction of Electric field and Magnetic field is perpendicular to each other and also perpendicular to the direction in which these electromagnetic waves travel.

Complete answer:
EM waves are transverse waves, that is they are measured by amplitude (height) and wavelength (the minimum distance between the highest point of two consecutive waves). This highest point is termed as Crest. Also, the lowest point in an EM wave is known as Trough.
Mechanical waves compose matter that undergo vibration at their own specific place, which means that the matter is not being transferred from one point in space to another for the transference of energy, instead they pass on that vibrational energy to the particle beside them and this chain continues. This property of mechanical waves is the main reason why they need a medium to transfer that vibrational energy from one particle to another.
But in case of electromagnetic waves, the energy is being transferred as time varying Electric field and Magnetic field, that is the EM energy is stored in the wave in the form of fields. So, they do not require a medium to transfer that energy from point in space to another. That is why, an EM wave can travel through anything – be it air, vacuum or even a solid material.

Note:
An electromagnetic wave can split into a range of frequencies, this is known as the electromagnetic spectrum. Examples of EM waves are, Radio waves, X-rays, Microwaves, Gamma rays, etc. The visible light that is the light emitted by the Sun is also an example of electromagnetic waves.