Lesson Plan

Define the electromagnetic spectrum and describe it in terms of frequencies and wavelengths

Explain how electromagnetic radiation is produced and describe the structure of an EM wave (perpendicular, in-phase E and B fields)

Order the bands of the spectrum (radio, microwave, infrared, visible, ultraviolet, X-ray, gamma) and relate frequency, wavelength, energy, and penetrating power

Distinguish subtractive (pigment) from additive (light) color mixing

Describe applications of each region of the spectrum and explain why low- and high-frequency radiation are used differently

15.1

"Light is a form of electromagnetic radiation (EMR). The term light usually refers to visible light, but this is not the only form of EMR. As we will see, visible light occupies a narrow band in a broad range of types of electromagnetic radiation." "All the EM waves mentioned above are basically the same form of radiation. They can all travel across empty space, and they all travel at the speed of light in a vacuum. The basic difference between types of radiation is their differing frequencies." "As frequency increases across the spectrum, wavelength decreases. Energy also increases with frequency. Because of this, higher frequencies penetrate matter more readily." "The frequencies corresponding to these wavelengths are $4.0 \times 10^{14} \text{ s}^{-1}$ at the red end to $7.9 \times 10^{14} \text{ s}^{-1}$ at the violet end. This is a very narrow range, considering that the EM spectrum spans about 20 orders of magnitude." "Mixing two of the primary pigment colors—magenta, yellow, or cyan—together results in a secondary color... This is called subtractive color mixing... In this case, the primary colors are red, green, and blue, and the secondary colors are cyan, magenta, and yellow... when all colors are subtracted, the result is no color, or black. When all colors are added, the result is white light."