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Homework Help: AC Voltage Expression and understanding

  1. Jul 19, 2012 #1
    1. The problem statement.

    AC voltage is expressed as 240 cos(2765t - 45°).
    Im trying to find the:

    Peak Voltage:
    RMS Voltage:
    Average Voltage:
    Peak-to-Peak Voltage:

    3. The attempt at a solution

    Peak Voltage: 240v
    RMS Voltage: 170v
    Average Voltage: 0v
    Peak-to-Peak Voltage: 480v

    I've worked on this but i feel like I am using the wrong equations to find the answer. such as Peak to Peak and RMS.

    Any ideas?
    Thanks for your help
  2. jcsd
  3. Jul 19, 2012 #2


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    Staff: Mentor

    Answers so far look correct to me.
  4. Jul 19, 2012 #3
    Thanks, I've reworked it about 3 times because I thought I was doing it wrong.
  5. Jul 21, 2012 #4


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    Science Advisor
    Homework Helper
    Gold Member

    I had a ham license from 1953 to about 1973 and used to love CW. Apparently they have lowered the exam standards there like everything else. Are the CW bands still alive and well? That would seem like the death knell to me...
  6. Jul 22, 2012 #5


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    Staff: Mentor


    The CW bands are good now -- as you know they cycle with sunspot activity, and we are near the peak of the 11 year cycle right now, so skip off the ionosphere is good right now. We just had Field Day recently (did you participate in those when you were active?), and our local club had a near record number of contacts. Great stuff.

    The dropping of the CW (Morse Code for the PF readers who are non-HAMs) requirement for getting HAM licenses was done by the FCC to bolster the ranks of the emergency response HAM operators, and has had very little effect on the HAM operators who enjoy long-distance CW contacts and contesting. Actually, I know several new HAMs who are learning CW after getting their license, because they have a general interest in all communications, and learning CW expands the modes that they can operate in.

    As an ARES EC for my city, I get e-mails each month that list the new HAM licenses that have been issued. The increase is dramatic since the FCC eliminated the CW requirement, and I am quite busy training up new HAM operators in how to be effective communicators in disaster situations. IMO, this was a great move by the FCC, and it has helped us locally in our disaster preparations significantly. (I basically live on top of the Hayward Fault, which is due to slip very soon....)

    </hijack> :biggrin:
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