We know that energy is transferred from one place to another by means of some kind of medium and the medium is pretty essential as it determines the rate of energy transfer. But what happens when there is no medium to transfer energy. How energy can be transferred via vacuum ? The most common example is the sun. Every second huge amount of energy is emitted from the sun which travels in the space and reaches various planets. The energy is transferred by electromagnetic waves. Electromagnetic waves are produced by the electric fields and magnetic fields when they oscillate perpendicular to each other.
The light itself is an electromagnetic wave. So, it can be easily said that the speed of electromagnetic wave is the speed of light i.e., 3 × 108 m/s.
Electromagnetic waves are caused by electromagnetic field. Electromagnetic field is that where both electric field and magnetic field are present. When both of these oscillate perpendicularly to each other, electromagnetic wave is generated which can travel through even vacuum. The energy carried by the electromagnetic wave is called radiant energy. In general, now a days electromagnetic waves transmit radio waves, infra-red radiation, gamma Rays. The wave length of the waves determine the visibility of these electromagnetic waves i.e. depending on the wavelength some waves are visible to bare eyes and some are invisible, it also determines the colour of the wave.
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