Why, it is childishly simple. Assuming sinusoidal waveforms, we get the average power by taking the average of the instantaneous power over a complete period. The instantaneous power of a "90 degrees out of phase" voltage*current is proportional to sin(x)*cos(x). The integral of sin(x)*cos(x) is (sin^2(x))/2. Pluging in the limits of the period 0 to 2*pi gives 0. Dividing by the period to get the average is still 0. Doing the same with and in-phase voltage*current means using either sin^2(x) or cos^2(x), which gives an answer of 1/2.Ok, I realize this to be true but how do you prove that a circuit whose current is 90 degrees out of phase with the driving voltage consumes no power, averaged over an entire cycle???
|Thread starter||Similar threads||Forum||Replies||Date|
|If you ever need to move away from FR4 -- I'd go talk to this guy.||Electronics Resources||0|
|Need help to understand I2C example code||Embedded Systems and Microcontrollers||15|
|P||Need Help in Fixing Acer Projector.||Technical Repair||0|
|B||Need white led for motion light||General Electronics Chat||9|
|Need Recommendation for Best Schematic/PCB software||General Electronics Chat||34|