Physics 14 SMC H.-F. Lai Homework Solutions Ch. The two components of an EM wave are oscillating electric field and magnetic field.
Light is electromagnetic waves.
The frequency of a radio wave is lower than that of visible light. The frequency of an X ray is higher than that of visible light. The visible light of the lowest frequency appears to be red, and that of the highest frequency appears to be violet. Radio waves have the lowest frequency among those three, and hence have the longest wavelength. For example, there is vacuum between the Sun and the Earth, and we are able to receive sun light on Earth.