Summary of Lecture on 10/22/03   

Humans aren't the only things that can have split personalities. As we learned in lecture today, Light has an identity crisis as well. Light can exist in two forms: waves and particles. In light waves, we can measure wavelength (the distance between crests on a wave), frequency (the number of waves that pass through something in one second), and speed ( 3x10^8 m/s in a vacuum). The equation associated with the wave properties is:

C= (Lambda)(nu)

where C is the speed of light in a vacuum (distance/time), Lambda is wavelength (distance/wave, usually m), and nu is frequency (waves/time or Hz).

The Second identity of light that we explored was as particles or photons. Normally, one photon of light has the energy to make one molecule react. The equation used to find the energy of a photon is:

E= h(nu)

 where E is the energy of a photon, h is Planck's constant (6.63x10^-34 J*s), and nu is wavelength.

In today's lecture we learned that light has a split personality. Light is

made up of waves that have electromagnetic oscilations. The distance

between the max point of one wave and the maximum point of the next wave is

called a wavelenght (lambda). The speed of a wave (distance/sec)=

wavelength (distance/wave)x frequency (waves/sec). Therefore, you can make

the equation c=wavelength x frequency, where c=3x10^8 m/s. Using this

equation, one can solve many problems dealing with the waves of light. For

example, to find the wavelength of a 900 mHz telephone, you would use the

equation c=wavelength x frequency. We are given the wavelength, so to solve

for frequnecy you take c(3x10^8)/wavelength (900x10^6 m)= .33m

(frequency).