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Current Affairs January 2024

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4

If the number of valence electrons of an atom is exactly 4a then the substance is called

A. a semiconductor

B. a conductor

C. an insulator

D. a cryogenic conductor

Correct Answer :

A. a semiconductor


Related Questions

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4

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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4

If a magnetic flux cuts across 200 turns at a rate of 2Wb/sa the induced voltage according to Faraday's law is about

A. 400 V

B. 100 V

C. 200 V

D. 600 V

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4

If you hold the conductor with right hand so that the stretched thumb points in the direction of the currenta then encircling fingers will give the direction of magnetic lines of force round the conductor. This is known as

A. Left hand cork screw rule

B. Right hand cork screw rule

C. Left hand rule

D. Right hand rule

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4

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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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

One coulomb of charge consists of ________ electrons.

A. 624× 10^16

B. 62.4 × 10^16

C. 6.24 × 10^16

D. 0.624 × 10^16

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4

Two similar polesa each 1Wba placed 1 m apart in air will experience a repulsive force of

A. 63000 N

B. 63 × 10^-3 N

C. 8 × 10^12 N

D. 796 kN

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4

How much is the flux in Weber in the above problem?

A. 2 x 10^-5

B. 2 x 10^-3

C. 2 x 10^5

D. 2 x 10^3

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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

How many electrons are needed in the valence orbit to give a material's stability?

A.

B.

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The unit of flux is _____ in cgs system.

A. Tesia

B. Gilbert

C. Maxwell

D. Oersted

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A magnetizing force of 1000 AT/m will produce a flux density of __________ i

A. 1.257 mWb/m^2

B. 0.63 Wb/m^2

C. 1.257 Wb/m^2

D. 0.63 mWb/m^2

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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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4

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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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

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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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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4

The branch of Engineering which deals with the magnetic effect of electric current is known as

A. Magnetism

B. Electromagnetism

C. Electrical engineering

D. Electronics engineering

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Hydrogen is an example of a _____ material.

A. Paramagnetic

B. Diamagnetic

C. Ferromagnetic

D. N on- magnetic

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4

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 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

Which of the following is used by temporary magnets as the magnetic material?

A. Hardened steel

B. Cobalt steel

C. Soft iron

D. Tungsten steel

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4

The B-H curve of ________ is not a straight line.

A. air

B. wood

C. silicon steel

D. soft iron

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4

The unit of flux density is

A. Wb/m

B. Tesla

C. At/m

D. N/Wb

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4

Electric field intensity at a point is numerically equal to ________ at that point.

A. potential gradient

B. potential difference

C. dielectric constant

D. the force

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4

The ability of a material to conduct magnetic flux through it.

A. Permittivity

B. Reluctivity

C. Conductivity

D. Permeability

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4

What is the SI unit of specific resistance or resistivity?

A. Ohm-circular mil per inch

B. Ohm-circular mil per foot

C. Ohm-m

D. Ohm-cm

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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

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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4

Calculate the permeability (in T/A. t/m) of a magnetic material that has a relative permeability of 300

A. 3.78 x 10^4

B. 3.78 x 10^-5

C. 3.78 x 10^-3

D. 3.78 x 10^-6