A loop of wire is lying flat on a tabletop. A uniform magnetic field is directed vertically UPWARDS such that it is perpendicular to the tabletop (and the loop). Beyond the edge of the table, the magnetic field is zero. Imagine that you are looking DOWN on the loop from above. Which of the following statements are true about the induced EMF in the wire loop? You will have to refer to Lenz's Law in order to determine the direction of the induced current.
True/False if the magnetic field suddenly decreases, the induced current will be in a clockwise direction
True/False if you keep the loop on the table, but pull it to the left, the induced current will be in a counter-clockwise direction
True/False if the loop suddenly grows in size, the induced current will be in a clockwise direction
True/False if you pull the loop out of the field (by sliding it off the table), the induced current will be in a clockwise direction
True/False Lenz's Law states that the induced current always leads to a magnetic field that OPPOSES the change in magnetic flux
To determine the direction of the induced current in the wire loop, we can use Lenz's Law, which states that the induced current always leads to a magnetic field that opposes the change in magnetic flux. Here's how we can apply Lenz's Law to each statement:
1. True: If the magnetic field suddenly decreases, the change in magnetic flux is a decrease, and Lenz's Law tells us that the induced current will create a magnetic field in the opposite direction to oppose this decrease. This corresponds to a clockwise current in the loop.
2. True: If you keep the loop on the table but pull it to the left, the change in magnetic flux is an increase. Lenz's Law states that the induced current will create a magnetic field in the opposite direction to oppose this increase. Therefore, the induced current will be counter-clockwise.
3. False: If the loop suddenly grows in size, the change in magnetic flux is again an increase. As per Lenz's Law, the induced current will create a magnetic field in the opposite direction to oppose this increase. Hence, the induced current will be counter-clockwise, not clockwise.
4. True: If you pull the loop out of the field (by sliding it off the table), the change in magnetic flux is a decrease. Lenz's Law states that the induced current will create a magnetic field in the opposite direction to oppose this decrease. Accordingly, the induced current will be clockwise.
5. True: This statement summarizes Lenz's Law accurately. It states that the induced current always opposes the change in magnetic flux. Therefore, the induced current will create a magnetic field that opposes the change in the external magnetic field.
To recap:
1. True
2. True
3. False
4. True
5. True