ABSTRACT
The electromagnetic spectrum spans more than 24 orders of magnitude with frequencies from <10 to >1024 Hz. The human body has senses that detect only a tiny portion of that spectrum. The molecules in our skin detect a small portion of the infrared (IR) range. Our skin feels warm or may “burn” if we are outside in bright sunlight. Healthy human eyes can detect frequencies in the range of 4.29 × 1014 to 7.50 × 1014 Hz. This is the visible range and the corresponding electromagnetic waves (EMWs) are called visible light. This chapter and the next will address the properties and some phenomena associated with visible light. Geometrical optics addresses the interaction of light with obstacles whose dimensions are much larger than the wavelength of light.
