Related Questions
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4
In electro-mechanical conversion devices like generators and motors the reason why a small air gap is left between the rotor and stator is to
A. permit mechanical clearance
B. increase flux density in air gap
C. decrease the reluctance of magnetic path
D. complete the magnetic path
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4
If two similar charges 1 coulomb each are placed 1 m apart in aira then the force of repulsion is
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4
A good conductor has how many valence electrons?
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What is the SI unit of specific resistance or resistivity?
A. Ohm-circular mil per inch
B. Ohm-circular mil per foot
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__________ is a substance of whose molecules consist of the same kind of atom.
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Three charges of +5 Ca -6 C and +9 C are placed inside a sphere. What is the total flux passing through the surface of sphere?
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4
Which of the following materials has the highest dielectric strength?
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______ is an electromagnet with its core in the form of a close magnetic ring.
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One farad equals
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The temperature coefficient of resistance of semiconductors is
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A law establishing the fact that the algebraic su of the rises and drops of the mmf around a closed loop of a magnetic circuit is equal to zero.
A. Kirchhoff's circuital law
B. Maxwell's circuital law
C. Ampere's circuital law
D. Coulomb's circuital law
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4
Mmf in a magnetic circuit corresponds to _____ in an electric circuit
C. Electric Field Intensity
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A substance that attracts pieces iron
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The core of a transformer heats up when its primary is fed from an ac source because of
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Flux linkages equals
A. Flux times area of core
B. Flux times number of turns times area of core
C. Flux times number of turns times length of core
D. Flux times number of turns
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4
What is used as the insulating material or dielectric in an electric ion
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4
Temporary magnets are commonly employed in
C. moving coils loudspeakers
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Core materials of a good relay have _________ hysteresis loop.
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How is mutual inductance between two coils decreased?
A. By using a common core
B. By moving the coils closer
C. By moving the coils apart
D. By increasing the number of turns of either coil
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4
Which of the following magnetic materials can be easily magnetized in both direction?
A. Soft magnetic materials
B. Hard magnetic materials
C. High hysteresis loss materials
D. Low hysteresis loss materials
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4
Flux density is measured in
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The force between two magnetic poles is _______ their pole strengths.
A. directly proportional to
C. inversely proportional to
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The resistivity of a conductor ___________ with an increase in temperature.
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What is another name for relative permittivity?
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If you hold the conductor with right hand so that the stretched thumb points in the direction of the currenta then encircling fingers will give the direction of magnetic lines of force round the conductor. This is known as
A. Left hand cork screw rule
B. Right hand cork screw rule
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Electric field intensity is a ________.
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4
If the number of valence electrons of an atom is more than 4a the substance is called
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4
All magnetic field originates from
A. moving electric charge
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Refers to the magnetic lines
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The electric flux density is a ________ quantity.