Finding the values of R with two loads

Discussion in 'Homework Help' started by justkiller91, Jan 10, 2013.

  1. justkiller91

    Thread Starter New Member

    Jan 10, 2013
    1
    0
    Hey there this is my problem: http://img715.imageshack.us/img715/9997/5help.png.

    So far i have been able to find the value of R3 (I think):

    LR1 = (75mA x 5v) = 375W
    = 375W x .10(bleeder?) =37.5W
    = (5v^2) / ( 37.5W) = .666K ohms = 6.67 ohms?

    What i would like help with:
    I am unsure of what to do next to find R2, would i do the same as above:
    LR2 = (100mA x 10v) = 1000W
    = 1000 x .10 = 100w?
    = (10v^2) / (100w) = 1 ohm?

    Am i on the right track or am i way out to lunch?
     
  2. WBahn

    Moderator

    Mar 31, 2012
    17,718
    4,788
    Way out to lunch.

    Note that, technically, at this point I have completely answered the question ask in your post. The following is additional, unsolicited, input.

    You are, for the most part, supplying units (thank you!), but you are not using them. You are also being very, very sloppy with your math.

    When you say

    X = a+b = c
    = d*f = g

    You are saying that X = c and that X = g because, if the left hand side of the equals sign is not provided, it is assumed to be the same as the left hand side of the equals sign preceding it.

    Consider the following:

    Q1) What is the current flowing in the Load 1?

    Q2) What is the voltage across Load 1?

    Q3) What is the current flowing in R3?

    Q4) What is the voltage across R3?

    Q5) What is the resistance of R3?

    Q6) What is the current flowing in R2?

    You should be able to take it from here.
     
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