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4

Core materials of a good relay have _________ hysteresis loop.

A. large

B. narrow

C. very large

D. very narrow

Correct Answer :

B. narrow


Related Questions

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The force between two charges placed a given distance apart ______ as the relative permittivity of the medium is increased.

A. increases

B. decreases

C. remains unchanged

D. becomes infinite

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4

What is the typical saturation flux density for most magnetic materials?

A. 4 Wb/m^2

B. 5 Wb/m^2

C. 1 Wb/m^2

D. 2 Wb/m^2

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4

Who discovered the most important electrical effects which is the magnetic effect?

A. Hans Christian Oersted

B. Sir Charles Wheatstone

C. Georg Ohm

D. James Clerk Maxwell

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4

Hipernik is an alloy containing __________ iron and __________ nickel.

A. 40% ; 60%

B. 60% ; 40%

C. 50% ; 50%

D. 70% ; 30%

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4

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?

A. 8 C

B. 14 C

C. 20 C

D. -6 C

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4

When the current flowsa the magnetic field ��. conductor is in what direction?

A. The same as the current direction

B. Opposite the current direction

C. Omnidirectional

D. In the direction determined by the left hand rule

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4

What is another name for relative permittivity?

A. Dielectric strength

B. Electric intensity

C. Potential gradient

D. Dielectric constant

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4

The hot resistance of an incandescent lamp is about _______ its cold resistance.

A. 10 times

B. 100 times

C. 5 times

D. 50 times

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4

If the number of valence electrons of an atom is less than 4a the substance is called

A. a conductor

B. a semiconductor

C. an insulator

D. a superconductor

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4

This paper does not exhibit electricity because it contains the same number of

A. protons and electrons

B. neutrons and electrons

C. neutrons and positrons

D. atoms

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4

The net electrical charge in an isolated system remains constant. This is known as

A. Law of conservation of charge

B. Coulomb's first law

C. Coulomb's second law

D. Law of conservation of energy

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4

Electric potential is a _______ quantity.

A. scalar

B. phasor

C. vector

D. variable

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4

The physical motion resulting from the forces of magnetic fields is called

A. Motor action

B. Rotation

C. Repulsion

D. Torque action

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4

Ohm's law cannot be applied to which material?

A. Copper

B. Silver

C. Silicon carbide

D. Aluminum

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A commercial alloy of aluminum nickela and iron with cobalta copper and titanium added to produce about 12 grades.

A. Alnico

B. Brass

C. Aluminum

D. Constantan

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4

Which of the following is a diamagnetic material?

A. Aluminum

B. Silver

C. Air

D. Cobalt

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What is the unit of reluctance?

A. Maxwell

B. Gauss

C. At/Wb

D. Weber

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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

The temperature coefficient of resistance of insulators is

A. zero

B. negative

C. positive

D. infinite

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When the relative permeability of a material is much greater than 1a it is called _______ material.

A. diamagnetic

B. ferromagnetic

C. paramagnetic

D. non-magnetic

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4

If the resistance of a material 2 m long and 2 m^2 in area of cross-section is 1.6 ×10^-8 ?a then its resistivity is

A. 3.2 × 10^-8 ?-m

B. 1.6 × 10^-8 ?-m

C. 0.64 × 10^-8 ?-m

D. 0.16 × 10^-8 ?-m

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4

The ability of a material to conduct magnetic flux through it.

A. Permittivity

B. Reluctivity

C. Conductivity

D. Permeability

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4

Who discovereda the relationship between magnetism and electricity that serves as the foundation for the theory of electromagnetism?

A. Luigi Galvani

B. Hans Christian Oersted

C. Andre Ampere

D. Charles Coulomb

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4

An effect which is generally used in the gausameter to measure flux density.

A. Skin effect

B. Magnetic effect

C. Hall effect

D. Flywheel effect

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4

What is the practical unit of electrical energy?

A. Watt

B. Kilowatt-hour

C. Kilowatt-second

D. Megawathour

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4

A substance that attracts pieces iron

A. Conductor

B. Semiconductor

C. Magnet

D. All of the above

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4

A germanium atom has an atomic weight of72. How many neutrons are there?

A.

B.

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4

An electron- volt (eV) is a unit of

A. Energy

B. Potential difference

C. Charge

D. Momentum

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4

Magnetic intensity is a

A. Phasor quantity

B. Physical quantity

C. Scalar quantity

D. Vector quantity

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4

Germanium atom has ______ protons and ______ electrons.

A. 32, 32

B. 32, 42

C. 42, 32

D. 34, 34