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Homework Help: Oscilloscope Pre-lab Question

  1. Jan 12, 2015 #1
    1. The problem statement, all variables and given/known data
    In the oscilloscope display above, the vertical sensitivity is 5mV/cm, and the horizontal sensitivity is 0.5μs/cm.
    A) find the amplitude of the sinusoidal voltage
    B) find the frequency of the sinusoidal voltagehttp://imgur.com/fnkXliz

    2. Relevant equations
    im not sure which equations to use for this question, if any are needed.

    3. The attempt at a solution
    I know you have to convert the units in this question im assuming. It also says in the question that each block is 1cm by 1 cm, and the top of the amplitude is about 3.2 cm, but that isn't the correct answer.
  2. jcsd
  3. Jan 12, 2015 #2
  4. Jan 12, 2015 #3


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    Ask yourself, what does it mean when it says 5 mV/cm? And so, what does it mean if you have a wave 3.2 cm tall on the screen?

    Ask yourself, what does it mean when it says 0.5μs/cm? And how long (in cm) is one wave of the signal on the screen? And so, what does that mean?
  5. Jan 12, 2015 #4
    i think it means (and correct me if im wrong) that there is 5 megavolts (5000000 volts) in every centimeter on the y-axis. So if the wave is 3.2 cm tall would you multiple 5mV by 3.2 to get the amplitude???
  6. Jan 12, 2015 #5


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    Staff: Mentor

    First of all, mV is milliVolts, not MegaVolts... :-)

    Next, I see the vertical amplitude as a little over 6 divisions tall. So the peak-to-peak amplitude will be a bit over 6 * 5mVpp. It's hard to tell if the question is asking for the peak or peak-to-peak "amplitude". Can you clarify that?

    And on the horizontal axis, how many divisions between the positive peaks of the waveform (or alternately use the positive-going zero crossings to find the waveform's period)
  7. Jan 12, 2015 #6


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  8. Jan 13, 2015 #7
    Okay so i got the first question right, it was asking for the peak not the peak to peak. So for the second part about finding the frequency, I counted roughly 3.2 blocks as the period, so the frequency is just 1/period right? im not sure what to put in for units though, i thought frequency was measured in Hz, but when i try to put the answer in online it says the units are wrong... any help?
  9. Jan 13, 2015 #8


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    3.2 cm is how much time ?
  10. Jan 13, 2015 #9
    Problem solved! thank you guys so much for the help :)
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