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Homework Help: Designing basic circuits to power devices

  1. Mar 22, 2010 #1
    Device requires a terminal voltage of 12 volts and a current of 2 Amps. Design a circuit using as many 3 ohm resistors as needed to properly power this device. The EMF is 24 Volts.

    2. Relevant equations
    Ohm's law: V=IR

    3. The attempt at a solution
    I know how to find equivalent resistance, but I don't know how to dissipate some of the voltage, in this case, get the voltage from 24 down to 12.
  2. jcsd
  3. Mar 23, 2010 #2
    Calculate the resistance of the device from the fact that V=12V and I=2A.
    If the pd across it is to be 12V but the supply is 24V, then you need a circuit in which there is 12V combined across the available 3 ohm resistors and 12V across the device.
    Does that help? Try both a series and parallel circuit to see which will do the job.