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: Electromagnetism homework question

  1. Jan 19, 2005 #1
    1. A simple generator has a 200-loop square coil 25.0cm on a side. How fast must it turn in a 0.550T field to produce a 120V peak output?

    area=(0.25)^2
    =6.25x10^-2

    E=-N(BA)/t
    t=-(300)(6.25x10^-2)(0-0.550T)/120V
    t=8.6x10^-2 s
    do you need to times it by 4 to get the time for one rotation??

    2. A motor has an armature resistance of 3.40ohms. If it draws 8.70A when running at full speed and connected to a 120V line, how large is the counter emf?
    V-Ir-Emf=0
    Emf=V-Ir
    =120-(8.7)(3.4)
    =90.4V
    Is this right????

    3. A 30cm diameter coil consists of 30 turns of circular copper wire 2.8mm in diameter. A uniform magnetic field, perpendicular to the plane of the coil, changes at a rate of 8.65x10^-3T/s. Determine the current in the loop.

    I have no idea how to start this question.
    Plz help...thx...
     
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted