Light

“Light” generally refers to the range of frequency we can see. However, just as dogs can hear a different range of sound frequencies than humans, so can some animals see a different range of light frequencies. Bees, for instance, can see ultraviolet frequencies. Humans have also invented ways of imaging things in light frequencies beyond the visible—you have probably heard of infrared and ultraviolet cameras. Therefore, people sometimes call infrared waves “infrared light” and ultraviolet waves “ultraviolet light.” However, probably because nothing has the capacity to see things in radio waves or gamma waves (even though we now have cameras that can image things in those wavelengths) you rarely (if ever) hear the terms “radio light” or “gamma light”.

Technically, you can call all electromagnetic radiation—everything on the spectrum— “light”. All of these electromagnetic waves are just streams of photons of different frequencies; visible light just happens to be the range of frequency we can see. We still call sounds that we can’t hear sound, so many people call electromagnetic radiation we can’t see light; they use the terms “electromagnetic radiation” and “light” interchangeably.

However, it’s important to understand that wavelength is the only difference between electromagnetic radiation on one end of the spectrum and the other end. The wavelength can give us frequency, color of the light, and energy of the wave—radio waves are very low energy; gamma waves are very high energy. The amplitude of each frequency can be different—you can have high amplitude radio waves, or low amplitude radio waves; they will be the same frequency and energy, just different intensities.

Amplitude and frequency are the only properties of electromagnetic radiation that can change. It’s always the same speed; it has no temperature or texture or size (except on a quantum scale, which you can forget about for now).

Electromagnetic radiation can, however, generate from different sources.

Next


Background Information for Activity #2: Spectroscopy: Electromagnetic Radiation | Electromagnetic Frequency | Light | Generating Electromagnetic Radiation | Sources of Electromagnetic Radiation | Reflection and Absorption | Atomic Spectroscopy | Molecular Spectrscopy