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
DONT GET THE ANSWER
To determine the direction of the induced current in each scenario, we need to consider Lenz's Law. Lenz's Law states that the induced current always 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 through the loop is a decrease. To oppose this change, the induced current will create a magnetic field in the opposite direction, which is clockwise when looking down on the loop.
2. True. If you pull the loop to the left while keeping it on the table, the magnetic field through the loop will decrease (since it extends beyond the edge of the table). To oppose this decrease, the induced current will generate a magnetic field in the opposite direction, which is counterclockwise when looking down on the loop.
3. False. If the loop suddenly grows in size, the magnetic field through the loop will not change. Lenz's Law states that the induced current opposes the change in magnetic flux, but in this case, there is no change in magnetic flux. Therefore, there will be no induced current.
4. False. If you slide the loop off the table, the magnetic field through the loop will decrease to zero. Applying Lenz's Law, the induced current will create a magnetic field in the opposite direction to oppose this decrease, which is counterclockwise when looking down on the loop.
5. True. Lenz's Law states that the induced current always opposes the change in magnetic flux. This means that the induced current always generates a magnetic field that opposes the change in the external magnetic field or the motion of the loop. This is why in the above statements, the induced currents are in directions that oppose the changes described.
So, the correct answers are:
True
True
False
False
True