Practice with Induced Currents (Changing Areas) Printer Friendly Version
Refer to the following information for the next two questions.

The shape of a 5-loop coil having a resistance of 100 ohms is changed while placed in an external magnetic field of 3 T.

As the area of the coil changes, in which direction will the induced current flow in the coil?
 If the coil uniformly changes its area from 4 cm2 to 12 cm2 in  0.5 seconds, then what is the magnitude of the current induced in the coils?

Refer to the following information for the next three questions.

The conducting rod shown below is moving at a constant velocity towards the right.

In which direction will induced currents flow through the loop?
 If the external magnetic field is 3 T, and the length of the conducting rod is 50 cm, what is the magnitude of the induced voltage?

 What external force is required to keep the rod moving at a constant velocity if there is a resistance of 100 ohms in the circuit?

Refer to the following information for the next two questions.

In the following diagrams, the angle between the external magnetic field and the coil's area vector changes from 0º to 30º.

In what direction would the induced currents in the coil flow?
 If this rotation were to be continued smoothly through numerous complete cycles (0º to 90º to 180º to 270º back to 0º), what type of current would be induced in the coil?

Refer to the following information for the next four questions.

A conducting bar slides across a frictionless surface in the +x direction. As it moves, it is simultaneously passing through a magnetic field directed into the plane of the table's surface, -z.
Realistically, the magnetic field will force the negative charge carriers, that is, the free conduction electrons within the metal, in which direction?

 Which end of the bar will be at a high potential?

 In which direction will the induced electric field within the bar point?

 Will an external force be required to keep the bar in motion as it moves through the magnetic field?

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