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What is the correct answer?

4

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

Correct Answer :

A. Oppose the change


Related Questions

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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 property of a material which opposes the creation of magnetic flux in it

A. Resistance

B. Reluctance

C. Permeance

D. Conductance

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4

Define as that pole which when placed in air from a similar and equal pole repels it with a force of newtons

A. North pole

B. South pole

C. Unit pole

D. Magnetic pole

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4

What is the value of the absolute permittivity of air?

A. 8.854 F/m

B. 8.854 × 10^-12 mF/m

C. 8.854× 10^-12 F/m

D. 8.854 × 10^-12 F/m

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4

Why is it that the magnitude of magnetomotive force required for air gap is much greater than that required for iron part of a magnetic circuit?

A. Because air is a gas

B. Because air has the highest relative permeability

C. Because air is a conductor of magnetic flux

D. Because air has the lowest relative permeability

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4

There are how many compounds available in nature?

A.

B.

C. 300a000

D. Unlimited

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4

A law that states that the polarity of the induced voltage will oppose the change in magnetic flux causing the induction.

A. Joule's law

B. Faraday's law

C. Coulomb's law

D. Lenz' law

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4

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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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

The magnetic potential in a magnetic circuit can be measured in terms of

A. Mmf

B. Emf

C. Farad

D. Coulomb

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4

What is the main advantage of temporary magnets?

A. The magnetic flux can be changed.

B. Hysteresis can be decreased.

C. Magnetic materials can be used.

D. Abundance of ferromagnetic material that can be temporarily magnetized.

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4

What determines the value of the temperature coefficient of resistance of a material?

A. length

B. cross-sectional area

C. volume

D. nature and temperature

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4

The permittivity of a material is given by one of the following formulas.

A. DE

B. E/D

C. D^2/E

D. D/E

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4

The magnetic flux of 2000 lines is how many Maxwells?

A.

B.

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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

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

Which of the following has the highest permeability?

A. Soft iron

B. Steel

C. Air

D. Permalloy

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4

The temperature coefficient of resistance of eureka is

A. p ositive

B. negative

C. almost zero

D. i nfinite

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4

One of the common application of an air- cored choke.

A. Radio frequency

B. Audio frequency

C. Power supply

D. Power transformer

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4

What is another name for relative permittivity?

A. Dielectric strength

B. Electric intensity

C. Potential gradient

D. Dielectric constant

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4

The emf produced in a wire by its motion across a magnetic field does not depend upon the

A. Diameter of the wire

B. Length of the wire

C. Orientation of the wire

D. Flux density of the field

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4

A t/m is a unit of

A. Mmf

B. Emf

C. Reluctance

D. Magnetizing force

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4

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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4

The net electrical charge in an isolated system remains constant. This is known as

A. Law of conservation of charge

B. Coulomb's first law

C. Coulomb's second law

D. Law of conservation of energy

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4

What is the measure of the density and sign of the electric charge at a point relative to that at some time?

A. Electric potential

B. Electric charge

C. Electric current

D. Electric intensity

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4

Flux density is measured in

A. Tesia

B. Weber

C. Ampere- turn

D. Maxwell

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4

Calculate the flux density that will be produced by the field intensity of 2000 a. t/m for a permeability of 126 x 10^-6 T/A.t/m

A. 0.252 G

B. 0.252 x 10^-2 T

C. 0.252 T

D. 0.252 x 10^-2 G

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4

What is the SI unit of conductivity?

A. Ohms/m

B. Ohms-m

C. Siemens-m

D. Siemens/m

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4

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

Defined as the number of lines per unit area through any substance in a plane at right angles to the lines of force

A. Flux

B. Flux lines

C. Flux density

D. Flux intensity