1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Could Someone Help Me With This Lenz's Law Question?

  1. Sep 8, 2011 #1
    The bar in figure Q31.5 moves on rails to the right with a velocity, v, and the uniform, constant magnetic field is directed out of the page. Why is the induced current clockwise? If the bar were moving to the left, what would be the direction of the induced current?
    (The figure is at the bottom of page 24 in the document linked below)

    My answer is;
    As Lenz's law states that the induced current in a conductor acts in the direction that opposes the charge that produced it. Consequently, the magnetic field is acting into the page, meaning that the induced current is clockwise (by the right hand rule).
    If the bar was moving to the left, the induced current would be counter-clockwise.

    If this correct?

    Thank you for any help =)

    http://www.electron.rmutphysics.com...-Serway-Beichne 6edr-4/31 - Faraday's Law.pdf
  2. jcsd
  3. Sep 9, 2011 #2
    For a moving conductor in a magnetic field can't you just use that the force on a charge q is F = q*VXB and this force causes a current?
  4. Sep 9, 2011 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    The picture didn't load here when I clicked on the link, but I can imagine what it was.

    You kind of just assert what the answer is. Can you explain in a bit more detail how you know the induced field points into the page?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook