Please help me! I am new here and I have a lot of Physics problems. Very close to failing this semester DX--A coil of insulated wire is wound many times around an iron bar. The wire is connected to a battery and a contact switch. The contact switch is alternately flipped closed and left closed, so the wire carries a current through it, and then flipped open and left open, so that the current stops. Describe what magnetic fields are created, if those magnetic fields in turn induce an emf, and whether the induced emf is in the direction of the original current or opposite
to it. THANK YOU!!!

Question

Please help me!  I am new here and I have a lot of Physics problems.  Very close to failing this semester DX--A coil of insulated wire is wound many times around an iron bar. The wire is connected to a battery and a contact switch. The contact switch is alternately flipped closed and left closed, so the wire carries a current through it, and then flipped open and left open, so that the current stops. Describe what magnetic fields are created, if those magnetic fields in turn induce an emf, and whether the induced emf is in the direction of the original current or opposite 
to it. THANK YOU!!!

anonymous · Answer

Lenz's law states that the direction of induced emf (or induced current) is such that it always tends to oppose the cause which produces it. Try to understand this law, it will help you answer the question.