Help with these circuit equations!

Discussion in 'General Electronics Chat' started by Jsean21, Jan 9, 2009.

  1. Jsean21

    Thread Starter Member

    Jan 8, 2009
    20
    0
    If R is 30k(ohms) and R2 is 10k(ohms), calculate the resisitance of R3 is V3 is to be 2V and the Vt(t=total, supply voltage) is 10V?

    What other resistor values could be used for R1, R2, and R3 but still ensure V3 is 2V if Vt is 10V

    i do electronics at college we've been given this worksheet on resistors and im absolutley baffeled on what i have to do, please can somebody give me the solution to this equation and explain how?

    thanks in advance
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    I think you are talking about a voltage divider circuit. The voltage across R3 will be

    VR3=(V*R3)/(R1+R2+R3)

    where V is the supply voltage

    The rest is calculations, try it.
     
  3. Jsean21

    Thread Starter Member

    Jan 8, 2009
    20
    0
    erm i understand what u mean but how exactly do we find R3 using the information from the question? also the circuit involved testing the voltage of resistors in a series circuit
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Solve the equation for R3 and plug the values of R1, R2, VR3 and Vsupply into the equation.
     
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