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4

The magnetic field of a magnetized iron bar when strongly heated

A. Becomes weaker

B. Becomes stronger

C. Reverses in direction

D. is unchanged

Correct Answer :

A. Becomes weaker


Related Questions

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All magnetic field originates from

A. moving electric charge

B. Iron atoms

C. Magnetic domain

D. Permanent magnets

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The force acting on a pole of 5 Wb is 25 N. What is the intensity of the magnetic field?

A. 5 N/Wb

B. 25 N/Wb

C. 125 N/Wb

D. 0.2 N/Wb

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4

The force of attraction or repulsion between two magnetic poles is inversely proportional to the square of the distance between them. This is known as

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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Magnetic field intensity is a ________ quantity.

A. scalar

B. phasor

C. vector

D. variable

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The uncharged particles which have no effect on its atomic charge.

A. Nucleons

B. Electrons

C. Protons

D. Neutrons

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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

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

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 ability of a mechanically stressed ferromagnetic wire to recognize rapid switching of magnetization when subjected to a dc magnetic field.

A. Wartheim effect

B. Wiedemann effect

C. Wiegand effect

D. Edison effect

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4

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

A. a metal

B. an insulator

C. a non-metal

D. a semiconductor

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4

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

A group of magnetically aligned atoms is called

A. Range

B. Lattice

C. Domain

D. Crystal

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Who developed the electromagnetic theory of light in 1862?

A. Heinrich Rudolf Hertz

B. Wilhelm Rontgen

C. James Clerk Maxwell

D. Andre Ampere

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4

Germanium atom has ______ protons and ______ electrons.

A. 32, 32

B. 32, 42

C. 42, 32

D. 34, 34

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4

The quantity 10^6 maxwells is equivalent to one

A. Weber

B. Gauss

C. Gilbert

D. Tesla

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Magnetic effects of the earth as a huge magnet with north and south poles.

A. Diamagnetic

B. Ferromagnetic

C. Terrestrial magnetism

D. Terrestrial ferromagnetism

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4

Steel is hard to magnetize because of its

A. Low permeability

B. High permeability

C. High density

D. High retentivity

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What is the SI unit of magnetic flux?

A. Tesla

B. Weber

C. Maxwell

D. Gauss

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Permeability means

A. The conductivity of the material for magnetic lines of force

B. The magnetization test in the material after exciting field has been removed

C. The strength of an electromagnet

D. The strength of the permanent magnet

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A principle that states that only two electrons with different spins are allowed to exist in a given orbit

A. Bohr's principle

B. Pauli exclusion principle

C. Avogadro's principle

D. Coulomb's principle

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4

A magnetic flux of 2.5 x10^4 Wb through an area of 5 x10^4 square meters results in

A. 5 Wb

B. 0.5 Tesia of flux density

C. 5x 10^-5 Wb of flux

D. 5000 Tesia of flux density

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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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The lagging effect between flux density of the material and the magne

A. Permeance

B. Eddy current

C. Hysteresis

D. R eluctance

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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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4

A 6- V battery is connected across a solenoid of 100 turns having a resistance of 2 ?a Calculate the number of ampere turns?

A.

B.

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Who demonstrated the theory of electromagnetic induction in 1831?

A. Michael Faraday

B. Andre Ampere

C. James Clerk Maxwell

D. Charles Coulomb

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4

The magnetic field around the conductor is determined by the

A. Size of the conductor

B. Amount of current

C. Current divided by the resistance

D. Resistance divided by the current

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4

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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The point in a magnet where the intensity of magnetic lines of force is maximum

A. Magnetic pole

B. South pole

C. North pole

D. Unit pole

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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