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Homework Help: Electric Generator - work on lightbulb, but not on motor, why?

  1. Aug 5, 2007 #1
    1. The problem statement, all variables and given/known data

    I made a eletric generator by connecting 3 motors (R/C car motor) to a spinning wheel. Each motor can generate approx 3 volts, it can generate approx 7.5 volt when I connected them in series.

    When I connect a motor output (approx 3 volt) to a flashlight light bulb, it works perfectly. I also try to connect to my eletrical shaver and the shaver motor spin as well. However, when I try to connect to another R/C car motor (the load), it doesn't move at all. I've tried to connect a 1.5v AA battery to the load and it spin perfectly.

    Does anyone know why? My friend told me that the eletric generator may not generate enough current... Is that true? If yes, how to solve the problem. If not, what will be the problem and what is the solution?

    2. Relevant equations
    V = I * R

    3. The attempt at a solution
    I measured the resistance of the motor and it is 0.

    I've tried to connect those 3 motors to boost the voltage to 7.5 volt but the R/C motor (load) didn't move a bit. :(

    I am really stuck. :frown:

    Thanks in advance.
    Last edited: Aug 5, 2007
  2. jcsd
  3. Aug 5, 2007 #2
    Well, Im guessing that the motors need DC current to work. What you're producing is AC current, and hence, your motor doesnt work. When you connect it across a battery, you get DC and not AC current.
  4. Aug 5, 2007 #3
    If you want to convert AC to DC, you might want to make a bridge rectifier circuit. There is a thread on it in the Electrical Engineering section of this forum.
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