Confused about Sensor size diferences
 

I`m trying to learn about the aspects of HDDSLR that produce video images.
I`d like to know about the relationship between sensor size, its resolution in megapixels, the related depth of field, the size of each pixel.
The Pentax K-X sensor, for example, is a litle bigger than the Canon EOS 7D, but the resolution (in megapixels) of the Canon is 50% bigger, being both APS-C cameras.
Why?
Could I relate the Pentax sensor size "almost" equal to 35mm academic cinema film as Canon sensor, meaning a 28mm in a Pentax would be similar to a 28mm in a 35mm film camera?
Ron

Wikipedia strikes again!

Image sensor format - Wikipedia, the free encyclopedia

Hope this helps...