What will the magnetic field surrounding a conductor do if the current in a conductor increases?
The drawing below illustrates the effect of counter emf. When the switch is open, no current will flow.
Current does not build up immediately when the switch is closed, because the counter emf opposes the
applied voltage. The polarity of the counter emf at the instant that the switch is closed is shown on the
enlarged potion of the conductor below.
On the conductor shown below, label the polarity of the counter emf at the instant the switch is closed.