Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Easy Physics problem I just can't get

  1. Feb 20, 2010 #1
    Easy Physics problem I just can't get :(

    1. The problem statement, all variables and given/known data

    In figure 27-62, a voltmeter of resistance RV = 380 Ω and an ammeter of resistance RA = 1.18 Ω are being used to measure resistance R in a circuit that also contains a resistance R0 = 100 Ω and an ideal battery of emf ε = 12.0 V. Resistance R is given by R = V/i, where V is the voltmeter reading and i is the current in the resistance R. However, the ammeter reading is not i but rather i', which is i plus the current through the voltmeter. Thus the ratio of the two meter readings is not R but only an apparent resistance R' = V/i'. If R = 61.2 Ω, what are (a) the ammeter reading in milliamperes, (b) the voltmeter reading (in V), and (c) R'?

    3. The attempt at a solution

    I was able to get part C, 52.71 ohms, which is correct.

    I got 90.36mA for part A, and 4.77 V for part B, but both of those are wrong.

    Please help me get these!
  2. jcsd
  3. Feb 20, 2010 #2
    Re: Easy Physics problem I just can't get :(

    drawing the figure given may help...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook