# energy in a capacitor and inductor

#### squirby

Joined Aug 21, 2009
15
hey guys! i'm a new member here..hope this is the correct section in which to post such a question.

was wondering, does anyone know why the energy in a conductor and inductor is given as an integral with respect to 'tau' (the Greek letter), instead of time. the limits of the integral are time though. i've been lookin everywhere for a reason for this but cannot find it.

any response would be much appreciated~

#### bundick

Joined Dec 19, 2007
97
Just a faint glimmer of some chats back in the 70's.
Wasn't the the little Greek guy meant to depict a "Small change in time, or Small change in current"?

#### Ratch

Joined Mar 20, 2007
1,070
squirby,

was wondering, does anyone know why the energy in a conductor and inductor is given as an integral with respect to 'tau' (the Greek letter), instead of time. the limits of the integral are time though. i've been lookin everywhere for a reason for this but cannot find it.
Easy. The variable of integration is known as the "dummy variable" in integral calculus. That is because the integral will be the same no matter if you use a letter from the Greek alphabet or an Egyptian hieroglyph. Different symbols are used for the integration limits and the integral equation so as not to be confusing when substituting the limits into the integration result.

Ratch