A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes sudde
nly. When viewed from above, what is the sense of the induced current in this coil as the field fades? a. The induced current flows counter-clockwise.
b. The induced current flows clockwise.
c. There is no induced current in this coil.
d. The current flows clockwise initially, and then it flows counter-clockwise before stopping.
Option B - The induced current flows counter-clockwise.
Explanation:
Faraday's law of electromagnetic induction states that whenever a conductor is placed in a changing magnetic field, an electromotive force is induced and that if the conductor circuit is closed, a current is induced which is the induced current. The magnitude of the EMF induced in the coil is therefore proportional to the rate of change of magnetic flux throughout the coil.
Meanwhile, the direction of the induced current is given by Lenz's law which states that the direction of the induced current will oppose the change in electromagnetic force that produced that current.
Since the magnetic field points upwards, the induced current will move in a direction to the left which is counterclockwise
If a negatively charged balloon is brought near one end of the rod but not in direct contact, then <u>the negative charges on the balloon repel the same amount of negative charges on the end of the rod that is close to the balloon</u>, and the positive charges stay at the balloon-side of the rod. The total charge of the rod is still zero, but the distribution of the charges are now non-uniform.
