1. Consider a circular loop of conducting wire. A permanent magnet is moved clos
ID: 1865902 • Letter: 1
Question
1. Consider a circular loop of conducting wire. A permanent magnet is moved close to the loop, so that the magnetic field through the surface enclosed by the loop increases. This changing magnetic field creates
A.) neither a potential difference across the loop nor a current flow in the loop.
B.) a current flow in the loop.
C.) a potential difference across the loop.
D.) both a potential difference across the loop and a current flow in the loop.
2. Consider a circular loop made of wood. A permanent magnet is moved close to the loop, so that the magnetic field through the surface enclosed by the loop increases. This changing magnetic field creates
A.) a current flow in the loop.
B.) both a potential difference across the loop and a current flow in the loop.
C.) a potential difference across the loop.
D.) neither a potential difference across the loop nor a current flow in the loop.
3. Consider a circular loop of conducting wire. A permanent magnet is moved away from the loop, so that the magnetic field through the surface enclosed by the loop decreases. This changing magnetic field causes the circular loop to create its own magnetic field. The magnetic field created by the circular loop points
A.) in the same direction as the field produced by the magnet.
B.) in the direction opposite the field produced by the magnet.
4. Consider a circular loop of conducting wire. A permanent magnet is moved close to the loop in a certain amount of time. This motion produces an emf across the loop. If the demonstration is repeated, except the magnet is moved faster toward the loop, so that the time taken to move the magnet is reduced, then the emf across the loop will
A.) increase.
B.) remain constant.
C.) decrease.
Explanation / Answer
1) D.) both a potential difference across the loop and a current flow in the loop.
Because, According to Faraday's law
induced emf in the loop = the rate of change of magnetic flux through the loop
this induced emf causes the induced current to flow.
2) C.) a potential difference across the loop.
Since wood is not a conductor current does not flow.
3) B.) in the direction opposite the field produced by the magnet.
Because, According to Lenz's law the direction of induced current is always such as to oppose the change in magnetic flux that generated it.
4) A.) increase.
because, emf = A*dB/dt
as dt decreases emf increases.
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