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Homework Help: Value on ammeter display

  1. Oct 12, 2016 #1
    1. The problem statement, all variables and given/known data
    What will the pointer of electrodynamic ammeter show (its natural frequency of oscillation is 5 Hz), if its input is energized by current:
    a) i (t) = 1.5 + 4 sin (3146 t)
    b) i (t) = 1.5 + 4 sin (2 t)
    Ammeter has a range of 6 A and the scale has 100 divisions.

    2. Relevant equations
    3. The attempt at a solution

    My solution is 25 but I don't understand the difference between a) (where the frequency is 500 Hz) and b) (0.318 Hz).
  2. jcsd
  3. Oct 12, 2016 #2


    User Avatar

    Staff: Mentor

    Hi sol59. smiley_sign_welcome.gif

    Describe what you understand by an electrodynamic ammeter.

    What do you understand is meant by a natural frequency of oscillation of 5 Hz in the context of this problem.

    Until you show you have done some work by yourself, we are not able to help you further.
  4. Oct 15, 2016 #3
    Hi, thanks for the reply:) It's ammeter with electrodynamic measuring mechanism (with one movable coil and one fixed coil). The natural frequency is the frequency at which the measuring mechanism tends to oscillate before the current is led into its input. I calculated the deflection as: (1.5*100)/6 = 25 If somebody could give me advice how to solve this problem I would be very glad.
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