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4

If the value of 25 a conductor is 1/255 per oCa then the value of 20is

A. 1/300 per oC

B. 1/250 peroC

C. 1/230 per oC

D. 1/260 per oC

Correct Answer :

B. 1/250 peroC


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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4

States that the ratio of the thermal conductivity is proportional to the absolute temperature for all metals.

A. Wien's displacement law

B. Hartleys law

C. Hall's law

D. Wiedemann Franz law

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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

If the magnetic material is located within a coil through which alternating current (60 Hz frequency) flowsa then __________ hysteresis loops will be formed

A.

B.

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4

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

As the magnetic intensity decreasesa the relative permeability of a magnetic material

A. decreases

B. remains the same

C. increases

D. becomes zero

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4

What is the SI unit of conductance?

A. Siemens

B. Mhos

C. Ohms

D. 1/Ohms

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4

Which of the following is a paramagnetic material?

A. Carbon

B. Bismuth

C. Copper

D. Oxygen

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4

Which of the following materials has the least hysteresis loop area?

A. soft iron

B. silicon steel

C. hard steel

D. wrought iron

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4

If the value of 25 of a conductor is 1/230 per oCa then the value of 0is

A. 1/180 peroC

B. 1/150 per oC

C. 1/280 per oC

D. 1/230 per oC

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4

Who discovered superconductivity in 1911?

A. Kamerlingh Onnes

B. Alex Muller

C. GeoryBednorz

D. Charles Coulomb

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4

The magnetic field inside a solenoid

A. is zero

B. is uniform

C. increases with distance from the axis

D. decreases with distance from the axis

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4

The direction of force o a current carrying conductor placed in a m found by

A. Cork screw rule

B. Fleming's left hand rule

C. Fleming's right hand rule

D. using a compass

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4

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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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

Under ordinary conditionsa a body is considered

A. positively charged

B. neutral

C. negatively charged

D. stable

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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 property of magnetic materials of retaining magnetism after withdrawal of the magnetizing force is known as

A. Retentivity

B. Reluctivity

C. Resistivity

D. Conductivity

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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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4

If the right handed bottle-opener cork screw is assumed to be along the conductor so as to advance in the direction of current flow, the motion of its handle will indicate the direction of magnetic flux produced around the conductor. This is known as

A. Right hand rule

B. Left hand rule

C. Cork screw rule

D. End rule

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4

Electron is a Greek word for

A. amber

B. Fire

C. Stone

D. Heat

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Hysteresis is a phenomenon of _________ in a magnetic circuit.

A. setting up constant flux

B. lagging of H behind B

C. lagging B behind H

D. leading B ahead H

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What is the SI unit of magnetic flux?

A. Tesla

B. Weber

C. Maxwell

D. Gauss

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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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Theory of ferromagnetic phenomena which assumes each atom is a permanent magnet which can turn freely about its center under the influence of applied field and other magnets.

A. Ewing's theory of ferromagnetism

B. Oersted's ferromagnetism theory

C. Maxwell's magnetic theory

D. Ampere's circuital law

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A magnetic material losses its ferromagnetic properties at a point called

A. Curie temperature

B. Inferred absolute temperature

C. Room temperature

D. Absolute temperature

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Refers to the non- metallic materials that have the ferromagnetic properties of iron.

A. Ferrites

B. Ferromagnetic

C. Diamagnetic

D. Paramagnetic

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

A. a semiconductor

B. a conductor

C. an insulator

D. a semi-insulator

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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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4

If the value of 25 a conductor is 1/255 per oCa then the value of 20is

A. 1/300 per oC

B. 1/250 peroC

C. 1/230 per oC

D. 1/260 per oC