# Power Outlet Signal

My grandpa asked me a question regarding the signal coming out of a power outlet. We know that the ground hole is always ground, and that between the
two power holes there is a 120 Hz sine wave signal. However, I don't know how exactly is that signal sent. That is to say, what are the node voltages at the holes? Is one hole giving the whole range of voltages while the other just stays at ground level (figure 1)? Or does each hole provide a staggered half-rectified sine wave (figure 2)? Thanks in advance for any help.
Figure 1:
http://i.imgur.com/iTaGQ.png
Figure 2:
http://i.imgur.com/afniI.png
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On Sun, 25 Mar 2012 00:02:31 -0500, snipped-for-privacy@nmt.edu (Billy) wrote:

Though I don't understand your drawing, this one is closest. Assuming everything is wired correctly and there are no faults in the system, you're correct the "ground" pin (the round one) is grounded. ;-)
The "neutral" pin (the left, larger, one, if looking at an outlet with the ground pin down) is also tied to ground at the service entrance panel. It may not be precisely at ground but should be very close (again, assuming no faults). The "hot" pin (the right/smaller pin) has 120VAC on it. The voltage on this pin will swing from 0V to +170V to 0V to -170V, 60 times a second.

No, this would cause all sorts of unnecessary grief, and would be less safe. Interestingly, if you fill in the rest of the two sine waves, you have a standard US 240V circuit. ;-)
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Thanks krw, that answers my question perfectly. Thanks for the quick reply!
grandpa asked me a question regarding the signal coming out of a power>outlet. We know that the ground hole is always ground, and that between the0>two power holes there is a 120 Hz sine wave signal. However, I don't know how9>exactly is that signal sent. That is to say, what are the node voltages at0>the holes? Is one hole giving the whole range of voltages while the other >just stays at ground level (figure 1)? Or does each hole provide a
staggered9>half-rectified sine wave (figure 2)? Thanks in advance for any help..>u>Figure 1: http://i.imgur.com/iTaGQ.png4.Though I don't understand your drawing, this one is closest. Assuming0everything is wired correctly and there are no faults in the system, you'reacorrect the "ground" pin (the round one) is grounded. ;-)d.The "neutral" pin (the left, larger, one, if looking at an outlet with the
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says...

http://en.wikipedia.org/wiki/Mains_electricity
http://en.wikipedia.org/wiki/Alternating_current
http://en.wikipedia.org/wiki/Domestic_AC_power_plugs_and_sockets
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On 24/03/2012 10:02 PM, Billy wrote:

1)The voltage between the two "power holes" is 120Volts rms, nominally sinusoidal at 60Hz, not 120Hz Frequency is measured in terms of 1/time for a complete cycle (e.g., from + peak to +peak) The 120V is a useful kind of average measure of the voltage magnitude.
2)It is full wave 120*(root 2)* sin(2*pi*60t) where (2*pi*60 is radians/sec and t is in seconds- 360 degrees = 2*pi radians) No rectification involved. This means that the voltage varies from 0 to +(120*root2 or +170V to back to 0 and down to -170V then back to 0 in 1/60 of a second, and repeating this process. This is the voltage between the "power holes".No rectification is involved. 3)As krw indicates neutral is tied to ground.
4, The term signal is somewhat inappropriate usage in the case of power transfer. Nothing is sent until you plug in a load- then the load impedance and the voltage determine the current and the power received by what is plugged into the outlet.
5) There is information on basic electric circuit analysis, including AC, from simple to more complex, on the net.
--
Don Kelly
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