1. Not finding help here? Sign up for a free 30min 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!

Solenoid circuit.

  1. Sep 23, 2010 #1
    1. The problem statement, all variables and given/known data

    A soft iron bar in a solenoid is placed in a circuit. There are two compasses, 1 is on the West side of the iron bar and the other is to the North. The circuit switch is open, which way will be compass needles be pointing?
    Which way will the compass needles be pointing if the switch is then closed?


    Is there a rule to solenoids?
     
  2. jcsd
  3. Sep 23, 2010 #2

    rl.bhat

    User Avatar
    Homework Helper

    when the switch is open, both needles will point towards north, because soft iron bar is not magnetized.
    When the switch is closed, soft iron gets magnetized. Then the the needle placed west side will point either east or west depending on the direction of the current in the circuit.
    If you follow the lines of magnetic field, you can see that the needle on the north side will be in the opposite direction compared to the needle on the west side.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook