Download Alternating Current Applet Activity

Alternating Current Applet Activity
Introduction
The root-mean-square (rms) value of an alternating current (or voltage) is that
value of the direct current (or voltage) that dissipates power in a resistor at the
same rate. In this activity you will determine the rms voltage of an ac resistor
circuit and use it to show that its equivalent dc value will deliver the same energy
to the resistor in the same time.
Directions
1. Open: http://ngsir.netfirms.com/englishhtm/Rms.htm
2. Set the waveform to “sinusoidal (full)”.
3. The maximum ac-voltage is 10V. Determine the a.c rms voltage (or d.c
voltage that will dissipate the same energy over one cycle).
Work:
Vrms
=
_________V
4. The resistance is set at 10. Using Ohm’s law determine the a.c rms current
that will flow.
Work:
Irms = _________A
5. Using the “shift d.c. V” slider set the d.c. voltage at your determined a.c rms
voltage. What do you notice about the power dissipated in the d.c. circuit?
___________________________________________________________
6. Using your answers to parts 3 and 4 determine the product of Vrms and Irms.
What does this tell you?
Work:
____________________________________________________________
7. The frequency of the ac generator is set at 50 Hz. Determine the time period
for one cycle.
Work:
T = ________s
8. Using your answers to parts 6 and 7, determine how much electrical energy is
dissipated by the resistor in the ac circuit or dc circuit over one cycle.
Work:
E = _________ J
9. Press “check” on the applet. How does the applet determine the energy
consumed per cycle for both a.c and d.c graphs?
_____________________________________________________________
10. Change the waveform to “sinusoidal (half)”. Determine the rms voltage for
this waveform. Explain how you determined this value.
Vrms = _________
Explanation:
11. Change the waveform to “square”. Determine the rms voltage for
this waveform. Explain how you determined this value.
Vrms = _________
Explanation: