The Visible Spectrum COLOR FREQUENCY (Hz)WAVELENGTH (nm) Red 4.0 4.8 x 10 14 700-630 Orange 4.8 5.1 x 10 14 630-590 Yellow5.1-5.4 x 10 14 590-560 Green5.4-6.1 x 10 14 560-490 Blue6.1-6.7 x 10 14 490-450 Violet6.7-7.5 x 10 14 450-400
Electromagnetic Spectrum In increasing energy, ROY G BIV
Light is an electromagnetic wave Or is it a Particle acting like a wave?
Nature of Light Like sound waves, light exhibits properties of waves. These are diffraction, reflection, refraction and interference. In addition, light waves also exhibit dispersion and polarization. Unfortunately, Light cannot be completely described by the Wave theory.
Nature of Light Light has particle-like properties as shown by Einstein's Photo-electric effect. Light is said to travel in photons or small packets of NRG. The Explanation Dual-nature of light
Refraction Light waves, like people waves, will slow down and bend or refract.
Refraction As a wave enters a piece of glass its velocity slows down and the wave is bent towards the normal line. As it exits it will speed up and is bent away from the normal line. Air Glass medium Surface Normal Incident Angle
Dispersion Light of different frequencies is refracted by different amounts Red Light (lower frequency, longer wavelengths) is bent the least. Blue Light (higher frequency, shorter wavelengths) is bent the most. Refraction is Dispersive
Wave Speed v = Sound (in air) ~ 344 m/s Light (in vacuum) ~ 3x10 8 m/s What is the wavelength of a sound wave which has a frequency of = 1000 Hz? 344 m/s = 1000 Hz = 344m/s/1000/s (Seconds cancel) = 0.34 meters 1/3 of a meter in size, 1000 of them each second!
Wave Speed c = Sound (in air) ~ 344 m/s Light (in vacuum) ~ 3x10 8 m/s What is the wavelength of a radio wave with = 94.1 FM? AM kHZ = 10 3 Hz FM MHz = 10 6 Hz 3x10 8 m/s = (94.1 x 10 6 Hz) = 3x10 8 m/s / 94.1 x 10 6 /s = 3.2 meters 3 meters in size, 94,100,000 of them each second!