Question

1. 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 , and whether the induced is in the direction of the original current or opposite to it. Justify your answer using

Answer 1

The current in a wire near to a metal part (Iron bar) would generate a magnetic field. This is generated by the relation between magnetic and electric fields, the maxwell equations.

The current is the same as the movement of electrons, which are charged particles, as the moved the electric field is generated.

In terms of the direction, is set by the right-hand rule. Depending on the drawing you have or how you understand the problem you can draw the direction of the field.

The field is in the perpendicular plane to the line or direction in which the current flows.

Also, when you turn off the circuit and the current stops, maybe a low current can be induced in the wire due to the magnetic field in the iron bar, but this magnetic field was generated by the circuit. In other words, the residual magnetic field after you turn off the circuit can induce current but is so low