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4

How many turns are needed to produce a magnetomotive force of 1000 A.t for a coil with 6 amperes?

A. 6000 turns

B. 600 turns

C. 167 turns

D. 67turns

Correct Answer :

C. 167 turns


Related Questions

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The B-H curve for ________ is a straight line passing through the origin.

A. cobalt

B. air

C. hardened steel

D. soft iron

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4

A magnetic circuit carries a flux iin the iron part and a fluxgin the air gap. What is the leakage coefficient?

A. i/g

B. i × g

C. g/ i

D. i + g

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4

If the value of 0 a conductor is 1/234 per oCa then the value of 18is

A. 1/218 per oC

B. 1/252 peroC

C. 1/272 per oC

D. 1/273 per oC

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4

The permeability of a material having a flux density of 5 Wb/m^2 is 10^-5 H/m. What is the value of magnetizing force?

A. 5 × 10^-5 N/Wb

B. 500 × 10^3 N/Wb

C. 4 × 10^7N/Wb

D. 4 × 10^7N/Wb

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4

The greater percentage of materials is _________.

A. diamagnetic

B. paramagnetic

C. ferromagnetic

D. non-magnetic

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4

The potential at a point due to a charge is 15 V. If the distance is times, the potential at the point will be

A. 5 V

B. 18 V

C. 45 V

D. 15 V

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4

What type of bond is formed when there exists some form of collective interactions between the (negatively charged) electrons and (positively charged) nuclei in a solid?

A. Ionic

B. Covalent

C. Metallic

D. Van der Waals

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4

The reluctance of a magnetic circuit varies with

A. length × area

B. area � length

C. length � area

D. length + area

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4

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

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

Materials that have very high permeabilities (hundreds and even thousands times of that of free space)

A. Paramagnetic

B. Non- magnetic

C. Ferromagnetic

D. Diamagnetic

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An alloy of 40 percent iron and 60 percent nickel.

A. Alnico

B. Permalloy

C. Hipernik

D. Manganin

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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

The ratio of the total flux (flux in iron path) to the useful flux (flux in air gap)

A. Leakage flux

B. Leakage current

C. Leakage coefficient

D. Leakage factor

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4

The core of a transformer heats up when its primary is fed from an ac source because of

A. permeability

B. ferromagnetism

C. reluctance of core

D. hysteresis loss

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4

The conduction of electricity across the surface of a dielectric is called

A. creepage

B. skin effect

C. surface effect

D. crosstalk

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The mass of proton is __________ the mass of an electron.

A. equal to

B. about 1837 times

C. less than

D. 200 tim es

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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

What is the diameter of an atom?

A. About 10^-10 m

B. About 10^-10 cm

C. About 10^-10 mm

D. About 10^-10 �m

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The phenomenon that when an electric current passes through an anisotropic crystala there is an absorption or liberation of heat due to the non-uniformity in current distribution.

A. Bridgman effect

B. Corona effect

C. Dember effect

D. Destriau effect

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Residual magnetism refers to the flux densitya which exists in the iron core when the magnetic field intensity is

A. Minimized

B. Reduced to zero

C. Maximize

D. Unity

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4

The reluctance of a magnetic circuit is not dependent on which of the following?

A. Number of turns of coil

B. Magnetomotive force

C. Flux density in the circuit

D. Current in the coil

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4

What determines the value of the temperature coefficient of resistance of a material?

A. length

B. cross-sectional area

C. volume

D. nature and temperature

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4

If the length and area of cross-section of a wire are doubleda then its resistance

A. becomes four times

B. becomes sixteen times

C. remains the same

D. becomes two times

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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

When the relative permeability of a material is slightly more than 1a it is called ______ material.

A. diamagnetic

B. ferromagnetic

C. paramagnetic

D. non-magnetic

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4

The emf induced in a coil due to the change of its own flux linked with it is called

A. Mutually induced emf

B. Dynamically induced emf

C. Statically induced emf

D. Self induced emf

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4

______ is an electromagnet with its core in the form of a close magnetic ring.

A. S olenoid

B. Paraboloid

C. Toroid

D. Cycloid

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4

The permittivity of a material is given by one of the following formulas.

A. DE

B. E/D

C. D^2/E

D. D/E

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4

A magnetic pole produces 5000 field lines. How much is the flux in webers? A. 50 × 10^-6

A. 5 × 10^-6

B. 500 × 10^-6

C. 500 × 10^-5