Final answer:
Electromagnetic waves can travel through empty space at the speed of light without requiring a medium, and this speed is the fastest possible in the universe. Different materials can affect light's speed and direction, and the variation in wavelengths and frequencies across the electromagnetic spectrum is what distinguishes different types of electromagnetic waves.
Step-by-step explanation:
Electromagnetic waves travel fastest through empty space, which is a region that lacks matter entirely. Unlike sound waves, which require a medium such as air, water, or solids to propagate, electromagnetic waves can pass through the vacuum of space unhindered at a constant speed known as the speed of light, approximately 300,000 kilometers per second or 3 × 108 m/s. This speed is considered the fastest possible in the universe.
It is important to note that there are materials through which light cannot pass, leading to absorption or reflection rather than transmission. For instance, light can travel through glass and water, although at slower speeds due to the medium's density, but it cannot travel through opaque substances like metals.
Electromagnetic radiation varies in wavelengths and frequencies across the electromagnetic spectrum. These variations account for the different types of electromagnetic waves, ranging from radio waves to gamma rays, with visible light occupying a small portion of this spectrum. The energy of an electromagnetic wave, such as a photon, can be expressed through Planck's law, where E = hν, with 'E' representing the energy, 'h' as Planck's constant, and 'ν' as the frequency of the photon.