Discuss how electromagnetic waves are formed from moving electric charges and how an electric field will generate a magnetic field which in turn will generate an electric field, and so on. The velocity of the EM waves are of only one speed, the speed of light, designated by the letter c. The formula for relating velocity, frequency and wavelength of WM waves was given and shown to be the same as the formula previously used when discussing light and sound. Since the velocity of EM waves is a constant, c, the formula can be rearranged to find the wavelength as c/f, showing that as the wavelength increases ( from gamma rays to radio waves) the frequency decreases.