A Note About Light

Discussion

2 replies

Posted by Preston Birdwell on July 19, 2015 at 3:13 PM

In the 1860's James Clerk Maxwell developed equations that describe an electromagnetic wave, i.e. light.

So, Maxwell wrote...

$\frac{1}{c^2}\frac{\partial^2 \mathbf E}{\partial t^2} - \nabla^2 \mathbf E = 0\, \quad \frac{1}{c^2}\frac{\partial^2 \mathbf B}{\partial t^2} - \nabla^2 \mathbf B = 0\,$

...and there was light. sad

The results of these wave equations should be obvious to the most casual observer. cool

For more on Maxwells' Equations, see this Wikipedia article.

--P

Posted by Eva McDermott on July 22, 2015 at 8:09 PM

Don't remember Maxwell's equations specifically, but I do remember studying them in college. cool I am sure a lot of people are saying "What? wink " .

Posted by Preston Birdwell on July 23, 2015 at 11:04 AM

Basically, the first of these two equations is a wave in the electric field E, and the second equation is a wave in the magnetic field B in the four dimensions, x, y, z and time, t. Physically, they represent an electro-magnetic wave in which the electric field and the magnetic field oscillate and are perpendicular to one another. The wave travels through a vacuum at the speed of light, c. The peak-to-peak wave length correlates directly to color of the light.

I studied wave equations in depth a long time ago, in a galaxy far, far, away. Fortunately, a photographer doesn't need to know about partial differential equations to see the beauty of the mathematics and the gorgeous light we see. If it were not for the work of Gauss, Ampere, and Maxwell, much of the technology we now take for granted would not exist.

--P