In general the frequency spectrum for Electromagnetic (e.g light, radio, etc) is continuous and thus between any two frequencies there are an uncountable infinity of possible frequencies (just as there are an uncountable number of numbers between 1 and 2).

Gamma rays

They only differ from each other in wavelength. Wavelength is the distance between one wave crest to the next. Waves in the electromagnetic spectrum vary in size from very long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom.

There are an infinite number of colors, but there is probably some limit as to how finely a person can distinguish between different intensities coming from each type of photoreceptor. First, the color is determined by the spectrum of the electromagnetic radiation in the visible range.

In a vacuum, all electromagnetic waves travel at the same speed. But not all electromagnetic waves are the same. Electromagnetic waves vary in wavelength and frequency. The speed of an electromagnetic wave is the product of its wavelength and frequency.

The EM spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency. The common designations are: radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma rays.

A wave can be described by its length, height (amplitude) and frequency. All waves can be thought of as a disturbance that transfers energy. Some waves (water waves and sound waves) are formed through the vibration of particles.

EM waves travel with a constant velocity of 3.00 x 108 ms-1 in vacuum. They are deflected neither by the electric field, nor by the magnetic field.

The only difference between them is their wavelength, which is directly related to the amount of energy the waves carry. The shorter the wavelength of the radiation, the higher the energy. The rainbow of colors that we see in visible light represents only a very small portion of the electromagnetic spectrum.