Power is energy (not current) over time. The well known i*v formula for (instantaneous) electrical power is not open to interpretation, and is quite easy to derive.
Voltage (aka potential) being defined as electric potential energy per unit charge(*), with electric PE being defined as the mechanical work that electric forces can potentially effect, when a charge q goes through a voltage variation of v volts the mechanical work effected on it by electric forces is q*v joules (can be negative). If this charge q results from a current i flowing for time t, we have q=i*t, so the work (energy) is q*v=i*t*v joules, so power is i*t*v/t = i*v watts. See also: http://en.wikipedia.org/wiki/Mechanical_work To Harry: I don't know of a special name for dP/dt, what would be your use for the second derivative of energy wrt time? Michel (*) To Paul: typing this makes me realize that you cannot consistently deny the concept of potential energy and accept that of voltage (potential) :-) ----- Original Message ----- From: "leaking pen" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, February 01, 2007 7:59 AM Subject: Re: [Vo]: electricity question > depends what you mean by electrical power. by my understanding, > wattage, the big way of measuring power, IS a change of electrical > current over time. i could be mistaken, my understanding of units of > electricity has always been iffy. > > On 1/31/07, Harry Veeder <[EMAIL PROTECTED]> wrote: >> >> If electrical power is P. >> >> Do electrical engineers have a special name for dP/dt? >> >> Harry >> >> > > > -- > That which yields isn't always weak. >
