11.2 Alternating Current

Question 1

What is RMS current?

Answer 1

The square root of the mean value of the square of the current in an AC circuit. This current would give the same power dissipation in a resistor in a DC circuit as the average power int he ate resistor in an AC circuit.

Question 2

What is a transformer?

Answer 2

A device that takes as input an alternating voltage and delivers as output an alternating voltage of the same frequency and different peak value.

Question 3

When flux is zero what is the value of the EMF and the current?

Answer 3

They have large values. The current has the same dependence on time as the voltage since they are in phase.

Question 4

What happens to the power in an AC circuit?

Answer 4

Because the voltage and the current constantly vary in an AC circuit the power dissipated in a resistor also varies. The average power dissipated is half of the peak power.

Question 5

What is the formula for the average power in an AC circuit?

Answer 5

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P = 1/2Po = 1/2VoIo = Vrms x Irms = V^2rms/R = RI^2rms