Results 1 to 5 of 5

Math Help - of equal resistance

  1. #1
    Junior Member
    Joined
    Feb 2008
    Posts
    27

    of equal resistance

    What resistance must be placed in parallel with a 149 Ohm resistor to make the equivalent resistance 124 Ohm?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member Peritus's Avatar
    Joined
    Nov 2007
    Posts
    397
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Feb 2008
    Posts
    27
    I'm still not sure what I need to use...
    I'm not really adding the resistance... I'm trying to find the resistance necessary to be placed parallel to make the equivalence resistance 124 ohm...

    still confused i guess...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member Aryth's Avatar
    Joined
    Feb 2007
    From
    USA
    Posts
    651
    Thanks
    1
    Awards
    1
    Well, we use the formula for parallel resistors to find the equivalent resistance for two resistors:

    \text{We have the following information: }

    R_1 = 149 \Omega

    R_{Total} = 124 \Omega

    \text{The Equation is: }

    \frac{1}{R_{Total}} = \frac{1}{R_1} + \frac{1}{R_2}

    \frac{1}{124} = \frac{1}{149} + \frac{1}{R_2}

    \frac{1}{124} - \frac{1}{149} = \frac{1}{R_2}

    \frac{149}{18476} - \frac{124}{18476} = \frac{1}{R_2}

    \frac{25}{18476} = \frac{1}{R_2}

    R_2*\frac{25}{18476} = 1

    25R_2 = 18476

    R_2 = \frac{18476}{25}

    R_2 = 739.04 \Omega

    And there you go.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Feb 2008
    Posts
    27
    you have been very helpful, I appreciate your knowledge and assistance beyond what I can express..

    Thank you
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. circuit resistance
    Posted in the Math Topics Forum
    Replies: 2
    Last Post: December 29th 2010, 09:06 PM
  2. air resistance
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: September 28th 2010, 01:57 AM
  3. Replies: 2
    Last Post: March 23rd 2009, 07:11 AM
  4. resistance in parallel
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: January 29th 2008, 01:01 PM
  5. Resistance at certain lux
    Posted in the Pre-Calculus Forum
    Replies: 14
    Last Post: October 12th 2007, 12:51 PM

Search Tags


/mathhelpforum @mathhelpforum