Electromagnetic Field Theory
Magnetic circuit with cross sectional area of 20 cm2 is to be operated at 50 Hz from 120 Vrms supply. The number of turns required to active a peak magnetic flux density of 1.8 T in the core flux is

 300.
 150.
 450.
 600.

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Electromagnetic Field Theory
A copper disc is rotated rapidly below a freely suspended magnetic needle. The magnetic needle starts rotating with velocity

 equal to that of disc and in the opposite direction.
 less than that of disc but in opposite direction.
 equal to that of disc and in the same direction.
 less than that of disc and in the same direction.

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Electromagnetic Field Theory
Two spheres of radius r1 and r2 are connected by a conducting wire. Each of the spheres has been given a charge Q. Now

 both of sphere will have same potential.
 larger sphere will have greater potential.
 larger sphere will have smalled potential.
 smaller sphere will have zero potential.

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Electromagnetic Field Theory
Which of the following statement regarding waveguides is incorrect?

Waveguides are usually air filled hollow conducting metallic tubes for transmitting UHF and microwaves
At frequencies below the cut off value the wave progresses across the waveguide after total reflections
At waveguide can be coupled to a coaxial cable
Waveguides can handle large power at UHF and microwaves

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