Question

A television set draws an rms current of 2.50 A from a 60 Hz power line. What is the average current, the average of the square of the current, and the amplitude of the current?

Answer 1

The RMS current is the "root mean square" average value, meaning it is the square root of the average of the square of the amplitude, i.e.

`I_(rms) = sqrt(bar(I^2))`

This means that the average of the square is the square of the RMS average, i.e.

`bar(I^2) = 6.25\ A^2`

The average current for a DC power line is 0, since it alternates between positive and negative values.

For waves, much of the time, the RMS is just the magnitude over `sqrt2`, which means that the total magnitude is
`|I| = sqrt2 cdot I_(rms) = (5sqrt(2))/2 approx 3.54\ A`