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4

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

A. cobalt

B. air

C. hardened steel

D. soft iron

Correct Answer :

B. air


Related Questions

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Hysteresis loss can be reduced by one of the following.

A. Increasing mmf of the circuit

B. Using material narrow hysteresis loop

C. Using ferromagnetic core

D. Laminating the magnetic circuit

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Which element has four valence electrons?

A. Conductor

B. Insulator

C. Semiconductor

D. Semi- insulator

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Who demonstrated that there are magnetic effects around every current-carrying conductor and that current-carrying conductors can attract and repel each other just like magnets?

A. Luigi Galvani

B. Hans Christian Oersted

C. Charles Coulomb

D. Andre Ampere

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What is the cgs unit of magnetomotive force?

A. Gilbert

B. Ampere- turn

C. Maxwell

D. Weber

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The temperature coefficient of resistance of a conductor ______ with an increase in temperature.

A. increases

B. decreases

C. remains the same

D. becomes negative

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The idea of preventing one component from affecting another through their common electric and magnetic field is referred to as

A. Hall effect

B. Grounding

C. Shielding

D. Limiting

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All matters (gasa liquid and solid) are composed of

A. Neutrons

B. Particles

C. Electrons

D. Atoms

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The magnetic flux through a coil changes. This results to the induced emf acting in a direction as to

A. Oppose the change

B. Aid the change

C. Either oppose or aid the change

D. Neither oppose nor aid the change

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__________ is a substance of whose molecules consist of the same kind of atom.

A. Mixture

B. Compound

C. Element

D. Isotope

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Defined as the ratio of the volume occupied by the atoms or ions in a unit cell divided by the volume of the unit cell and is used to measure the compactness of a crystal.

A. Atomic packing factor (APF)

B. Ionic Packing Ratio (IPR)

C. Atomic compacting factor (ACF)

D. Ionic compacting ratio (ICR)

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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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The total number of magnetic lines of force in a magnetic field is called

A. Magnetic flux

B. Magnetic flux density

C. Magnetic flux intensity

D. Magnetic potential

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Lenz's law is the consequence of the law of conservation of

A. Energy

B. Charge

C. Field lines

D. Momentum

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The force between two magnetic poles is _______ their pole strengths.

A. directly proportional to

B. the sum of

C. inversely proportional to

D. the product of

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The unit of electrical energy is

A. Joule

B. Watt- second

C. Kilowatt hour

D. All of these

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Paramagnetic substance has a relative permeability of

A. Slightly less than one

B. Equal to one

C. Slightly equal to one

D. Very much greater than one

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The force of attraction or repulsion between two magnetic poles is directly proportional to their strengths.

A. Newton's first law

B. Faraday's first law of electromagnetic induction

C. Coulomb's first law

D. Coulomb's second law

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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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Ohm's law can be used only to a _____ circuit or component.

A. Unilateral

B. Exponential

C. Trivalent

D. Linear

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A group of magnetically aligned atoms is called

A. Range

B. Lattice

C. Domain

D. Crystal

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What is used as the insulating material or dielectric in an electric ion

A. Oiled paper

B. Mica

C. Paraffin

D. Tit anate compound

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______ 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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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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Bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions

A. Ionic bond

B. Covalent Bond

C. Electrostatic Bond

D. Metallic bond

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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

Electric lines of force leave or enter the charge surface at an angle of

A. 30o

B. 45 o

C. 90o

D. depending upon the angle of launch and entry

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The magnetic flux of 2000 lines is how many Maxwells?

A.

B.

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The ratio of the permeability of material to the permiabiity of air or vacuum.

A. Relative permeability

B. Relative permittivity

C. Relative conductivity

D. Relative reluctivity

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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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The permeability of permalloy is

A. Very much greater than permeability of air

B. Slightly greater than permeability of air

C. Slightly less than permeability of air

D. Equal to the permeability of air