Who developed the electromagnetic theory of light in 1862?
Heinrich Rudolf Hertz
Wilhelm Rontgen
James Clerk Maxwell
Andre Ampere
Correct Answer :
C. James Clerk Maxwell
Related Questions
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
Right hand rule
Left hand rule
Cork screw rule
End rule
The property of magnetic materials of retaining magnetism after withdrawal of the magnetizing force is known as
Retentivity
Reluctivity
Resistivity
Conductivity
A magnetic circuit carries a flux iin the iron part and a fluxgin the air gap. What is the leakage coefficient?
i/g
i × g
g/ i
i + g
How many turns are needed to produce a magnetomotive force of 1000 A.t for a coil with 6 amperes?
6000 turns
600 turns
167 turns
67turns
The magnetic materials should have a large hysteresis loss for one of the following applications.
Transformers
ACmotors
Permanent Magnets
DC generators
What is the other name for dielectric strength?
Breakdown voltage
Electric intensity
Potential gradient
Dielectric constant
All magnetic field originates from
moving electric charge
Iron atoms
Magnetic domain
Permanent magnets
Materials whose permeabilities are slightly greater than that of free space
Paramagnetic
Non- magnetic
Ferromagnetic
Diamagnetic
When the ferromagnetic substance is inserted in a current- carrying solenoida the magnetic field is
Greatly decreased
Greatly increased
Slightly decreased
Slightly increased
Which of the following is a natural magnet?
Steel
Magnesia
Lodestone
S oft iron
The emission of electrons from hot bodies is called
Radiation effect
Edison effect
Skin effect
Half effect
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.
Ewing's theory of ferromagnetism
Oersted's ferromagnetism theory
Maxwell's magnetic theory
Ampere's circuital law
A magnetic field is
The current flow through space around a permanent magnet
The force set up when current flows through a conductor
The force that drives current through a resistor
The force between the plates of a charged capacitor
The permeability of a material having a flux density of 5 Wb/m^2 is 10^-5 H/m. What is the value of magnetizing force?
5 × 10^-5 N/Wb
500 × 10^3 N/Wb
4 × 10^7N/Wb
4 × 10^7N/Wb
States that the ratio of the thermal conductivity is proportional to the absolute temperature for all metals.
Wien's displacement law
Hartleys law
Hall's law
Wiedemann Franz law
Who discovereda the relationship between magnetism and electricity that serves as the foundation for the theory of electromagnetism?
Luigi Galvani
Hans Christian Oersted
Andre Ampere
Charles Coulomb
The diameter of a hydrogen atom is approximately ______ cm.
1.1 x 10^-6
1.1 x 10^7
1.1 x 10^-8
1.1 x 10^-9
Hysteresis refers to the ______ between flux density of the material and the magnetizing force applied.
Leading effect
Ratio
Equality
Lagging effect
Flux density is measured in
Tesia
Weber
Ampere- turn
Maxwell
The B-H curve for ________ is a straight line passing through the origin.
cobalt
air
hardened steel
soft iron
The branch of Engineering which deals with the magnetic effect of electric current is known as
Magnetism
Electromagnetism
Electrical engineering
Electronics engineering
The magnetic energy stored in an inductor is ______ current.
Directly proportional to
Inversely proportional to
Directly proportional to the square of
Inversely proportional to the square of
The temperature coefficient of resistance of eureka is
p ositive
negative
almost zero
i nfinite
The reluctance of a magnetic circuit is not dependent on which of the following?
Number of turns of coil
Magnetomotive force
Flux density in the circuit
Current in the coil
The dielectric constant of most materials lies between
1 and 10
10 and 20
20 and 50
50 and 100
The force of attraction or repulsion between two magnetic poles is directly proportional to their strengths.
Newton's first law
Faraday's first law of electromagnetic induction
Coulomb's first law
Coulomb's second law
Electromotive force in a circuit
causes free electrons to flow
increases the circuit resistance
maintains circuit resistance
is needed to make the circuit complete
The ratio of the permeability of material to the permiabiity of air or vacuum.
Relative permeability
Relative permittivity
Relative conductivity
Relative reluctivity
Who demonstrated that there are magnetic effects around every current-carrying conductor and that current-carrying conductors can attract and repel each other just like magnets?
Luigi Galvani
Hans Christian Oersted
Charles Coulomb
Andre Ampere
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
Right hand rule
Left hand rule
Cork screw rule
End Rule