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The relative permeability of a magnetic material is 10^5. What is its permeability?

A. 4 × 10^5 H/m

B. 4 × 10^-12 H/m

C. 4× 10^-2 H/m

D. 4 × 10^7H/m

Correct Answer :

C. 4× 10^-2 H/m


Related Questions

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Which of the following electric quantities is vector in character?

A. Field

B. Charge

C. Energy

D. Potential Difference

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What is the relative permittivity of air?

A.

B.

C. 8.854 × 10^-12

D. 4 × 10^7

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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

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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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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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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What is the practical unit of electrical energy?

A. Watt

B. Kilowatt-hour

C. Kilowatt-second

D. Megawathour

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The contribution to the ionization in an ionization chamber by electrons liberated from t he walls.

A. Skin effect

B. Walt effect

C. Hall effect

D. Edison effect

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The magnetic energy stored in an inductor is ______ current.

A. Directly proportional to

B. Inversely proportional to

C. Directly proportional to the square of

D. Inversely proportional to the square of

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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

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One ampere- turn is equivalent to _____ gilberts

A.

B.

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The dielectric constant of most materials lies between

A. 1 and 10

B. 10 and 20

C. 20 and 50

D. 50 and 100

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An alloy of 22 percent iron and 78 per cent nickel.

A. Permalloy

B. Alnico

C. Constantan

D. M anganin

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What is another name for relative permittivity?

A. Dielectric strength

B. Electric intensity

C. Potential gradient

D. Dielectric constant

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The air space between poles of magnets

A. Air gap

B. Free space

C. Vacuum

D. Atmosphere

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One weber of flux is equal to _______ magnetic lines of force.

A. 10^6

B. 10^10

C. 4 × 10^7

D. 10^8

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A substance that attracts pieces iron

A. Conductor

B. Semiconductor

C. Magnet

D. All of the above

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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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A factor used to correct for the electrostatic forces of the more distant ions in an ionic solid.

A. Avogadro's number

B. Planck's constant

C. Boltzmann's constant

D. Madelung constant

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Another term for corona discharge.

A. Lightning

B. Sparking

C. Aurora

D. Corona Effect

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A positively charged body has

A. deficit of electrons

B. excess of neutrons

C. excess of electrons

D. deficit of protons

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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?

A. 8 C

B. 14 C

C. 20 C

D. -6 C

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The force acting on a unit n- pole placed at that point is called

A. Magnetic field intensity

B. Electric field intensity

C. Electromagnetic field intensity

D. Intensity magnetization

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The force between two magnetic poles is _____ their poles strength.

A. equal to

B. directly proportional to

C. inversely proportional to

D. directly proportional to the square root of

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The magnetic materials should have a large hysteresis loss for one of the following applications.

A. Transformers

B. ACmotors

C. Permanent Magnets

D. DC generators

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4

What determines the atomic number of an element?

A. The number of protons

B. The number of electrons

C. The number of neutrons

D. The number of neutrons and protons

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Back emf refers to the

A. Current equal to the applied emf

B. Opposing emf

C. Current opposing the applied emf

D. Voltage opposing the applied emf

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The greater percentage of materials is _________.

A. diamagnetic

B. paramagnetic

C. ferromagnetic

D. non-magnetic

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Electronic current in a wire is the flow of ____________ electrons.

A. free

B. valence

C. bound

D. loose

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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