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 a wire loop, we can apply Lenz's Law, which states that the induced current always opposes the change in magnetic flux.
Let's analyze each statement:
1. True. If the magnetic field suddenly decreases, the change in magnetic flux will be such that the induced current creates a magnetic field that opposes the decrease. By using your right hand with the thumb pointing in the direction of the decreasing magnetic field, your fingers will curl in a clockwise direction, indicating the direction of the induced current.
2. True. If you keep the loop on the table but pull it to the left, the magnetic field does not change. Therefore, there is no change in magnetic flux, and no induced current is generated.
3. False. If the loop suddenly grows in size, the magnetic field passing through the loop will increase. To oppose this increase, the induced current will create a magnetic field in the opposite direction. Using the right-hand rule, it can be determined that the induced current will be in a counter-clockwise direction.
4. True. If you pull the loop out of the magnetic field (by sliding it off the table), the magnetic field passing through the loop will decrease. To oppose this decrease, the induced current will create a magnetic field in the same direction as the original magnetic field. Therefore, the induced current will be in a clockwise direction.
5. True. As mentioned earlier, Lenz's Law 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 original magnetic field.
In summary:
1. True, the induced current will be in a clockwise direction.
2. True, no induced current is generated.
3. False, the induced current will be in a counter-clockwise direction.
4. True, the induced current will be in a clockwise direction.
5. True, Lenz's Law states the induced current always opposes the change in magnetic flux.