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Current Affairs January 2024

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Who discovered the most important electrical effects which is the magnetic effect?

A. Hans Christian Oersted

B. Sir Charles Wheatstone

C. Georg Ohm

D. James Clerk Maxwell

Correct Answer :

A. Hans Christian Oersted


Related Questions

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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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Who discovered superconductivity in 1911?

A. Kamerlingh Onnes

B. Alex Muller

C. GeoryBednorz

D. Charles Coulomb

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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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What determines the atomic number of an element?

A. The number of protons

B. The number of electrons

C. The number of neutrons

D. The number of neutrons and protons

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An effect which is generally used in the gausameter to measure flux density.

A. Skin effect

B. Magnetic effect

C. Hall effect

D. Flywheel effect

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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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A law that states that the current in a thermionic diode varies directly with the three- halves power of anode voltage and inversely with the square of the distance between the electrodesa provided operating conditions are such that the current is limited only by the space charge.

A. Hall's law

B. Joule's law

C. Child's law

D. Coulomb's law

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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 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

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A law stating that the magnetic susceptibilities of most paramagnetic substances are inversely proportional to their absolute temperatures.

A. Curie's Law

B. Child's Law

C. CR Law

D. Curie-Weiss Law

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What is the unit of magnetomotive force?

A. Volt

B. Tesla

C. Ampere- turn

D. Weber

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If on looking at any one end of a solenoid; the direction of current flow is found to be clockwise then the end under observation is a south pole. This is known as

A. Right hand rule

B. Left hand rule

C. Cork screw rule

D. End Rule

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Defined as the flux density produced in it due to its own induced magnetism

A. Magnetic field intensity

B. Electric field intensity

C. Electromagnetic field intensity

D. Intensity magnetization

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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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A magnetic pole produces 5000 field lines. How much is the flux in webers? A. 50 × 10^-6

A. 5 × 10^-6

B. 500 × 10^-6

C. 500 × 10^-5

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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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Magnetic fields do not interact with

A. Moving permanent magnets

B. Stationary permanent magnets

C. Moving electric charges

D. Stationary electric charges

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Which of the following has the least number of valence electrons?

A. Conductor

B. Semiconductor

C. Insulator

D. Semi- insulator

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The unit of flux density is

A. Wb/m

B. Tesla

C. At/m

D. N/Wb

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Electric field intensity is measured in

A. volts/meter

B. Newton/meter

C. Newton-meter

D. Amperes/meter

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When the relative permeability of a material is much greater than 1a it is called _______ material.

A. diamagnetic

B. ferromagnetic

C. paramagnetic

D. non-magnetic

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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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The flux density in an air-cored coil is 10^-3 Wb/m^2. With a cast iron core of relative permeability 100 inserteda the flux density will become

A. 10^-3 Wb/m^2

B. 10^-2 Wb/m^2

C. 10^3 Wb/m^2

D. 0.1 Wb/m^2

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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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A negative ion results when an atom gains an additional

A. Electron

B. Proton

C. Neutron

D. Atom

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Germanium atom has ______ protons and ______ electrons.

A. 32, 32

B. 32, 42

C. 42, 32

D. 34, 34

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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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Whenever a flux inking a coil or current changesa an emf is induced in it. This is known as

A. Joule's Law

B. Coulomb's Law

C. Faraday's first law of electromagnetic induction

D. Faraday's second law of electromagnetic induction

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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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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