In this problem, you will use Lenz’s law to explore what happens when an electromagnet is activated a short distance from a wire loop. You will need to use the right-hand rule to find the direction of the induced current. Figure Iron core Switch open Part F < 1 of 2 Correct Now the switch on the electromagnet is reopened. The magnitude of the external magnetic flux through the wire loop increases, B. decreases, C. remains constant), and there is (A. zero, B. a clockwise, C. a counterclockwise) current induced in the loop (as seen from the left. Enter the letters corresponding to the responses that correctly complete the statement above. For example: A, C ? View Available Hint(s) Submit
The Correct Answer and Explanation is:
Correct answer: B, C
Explanation (300 words):
When the switch on the electromagnet is reopened, the current flowing through the electromagnet stops. This causes the magnetic field produced by the electromagnet to decrease. Since the magnetic field is linked to the magnetic flux through the nearby wire loop, this change reduces the magnetic flux through the loop. Magnetic flux refers to the product of the magnetic field strength and the area it penetrates, considering the angle between the field and the area vector. Therefore, the magnitude of the external magnetic flux through the wire loop decreases. This corresponds to option B.
According to Lenz’s law, any change in magnetic flux through a loop induces a current that opposes the change in flux. In this scenario, the magnetic flux is decreasing, so the induced current must produce a magnetic field that tries to maintain the original field direction. To do this, the induced current must circulate in a direction that produces a magnetic field aligned with the original field of the electromagnet.
The direction of the induced current can be determined using the right-hand rule. If the magnetic field initially pointed to the right (as seen from the left side of the loop), a decreasing field would require a current that produces a rightward field. To achieve this, the induced current must flow in a counterclockwise direction (when viewed from the left). This corresponds to option C.
In conclusion, reopening the switch decreases the magnetic flux through the loop, and a counterclockwise current is induced to oppose the loss of the magnetic field. This behavior is consistent with both Faraday’s law of electromagnetic induction and Lenz’s law, which govern how electric currents are generated in response to changing magnetic environments. Thus, the correct choice is B, C.
