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5/31 MCQs for:

Electromagnetism

A square coil of wire with 15 turns and an area of 0.40 m2 is placed parallel to a magnetic field of 0.75 T. The coil is flipped so its plane is perpendicular to the magnetic field in 0.050 s. What is the magnitude of the average induced emf?

36 V

45 V.

90 V.

6.0 V.

An electric generator transforms:

Alternating current into direct current.

Mechanical energy into electrical energy.

Electrical energy into mechanical energy.

Direct current into alternating current.

If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor:

Increases to twice its original value.

Decreases to one-fourth its original value.

Increases to 4 times its original value.

Decreases to one-half its original value.

The coil of a generator has 50 loops and a cross-sectional area of 0.25 m2. What is the maximum emf generated by this generator if it is spinning with an angular velocity of 4.0 rad/s in a 2.0 T magnetic field?

400 V.

100 V.

200 V.

50 V.

Suppose that you wish to construct a simple AC generator with an output of 12 V maximum when rotated at 60 Hz. A magnetic field of 0.050 T is available. If the area of the rotating coil is 100 cm2, how many turns are needed?

16.

32.

64.

128.