Electromagnetic induction Flashcards
A loop of wire lies in the xy plane in a region with a constant magnetic field, with magnitude B, in the positive z direction. Which of the following situations will cause the magnetic flux through the loop to decrease?
The loop of wire is moved upwards (positive z direction) at a constant velocity.
The loop of wire is moved to the right (positive x direction) at a constant velocity
More wire is added to the loop, causing the circumference of the loop to double.
The loop of wire is rotated such that it becomes oriented in the yz plane.
The loop of wire is rotated such that it becomes oriented in the yz plane.
Which statement best describes Faraday’s law?
A change in the magnetic flux across a surface induces a voltage along the loop enclosing that surface
A magnetically-induced electric current always creates an opposite force to the one inducing it
The total electric flux out of a surface is proportional to the charge enclosed by that surface.
A change in the magnetic flux across a surface induces a voltage along the loop enclosing that surface
A magnetic braking system for a car is constructed by attaching a conducting disk (radius R and thickness h) to each car wheel. A portion of each disk is near an electromagnet that can be turned on when one needs to brake. The magnetic field from each electromagnet is perpendicular to the surface of each corresponding disk. For a given car speed and a given set of electromagnets, what happens if we make the disks thicker (h bigger)?
Nothing, the braking torque from the magnetic brakes will be the same.
The braking torque from the magnetic brakes will be reduced
.The braking torque from the magnetic brakes will be increased
.The braking torque from the magnetic brakes will be increased
