Who discovered that a current-carrying conductor would move when placed in a magnetic field?
Michael Faraday
Andre Ampere
Hans Christian Oersted
Gustav Robert Kirchhoff
Correct Answer :
A. Michael Faraday
Related Questions
When a wire loop is rotated in a magnetic field the direction of the induced emf changes one in every _______ revolution
The phenomenon by which a subtracts pieces of iron
Magnetism
Electromagnetism
Naturalism
Materialism
The air space between poles of magnets
Air gap
Free space
Vacuum
Atmosphere
What is the usual value of leakage coefficient for electrical machines?
0.5 to 1
1 to 5
5 to 10
1.15 to 1.25
The unit of flux is _____ in cgs system.
Tesia
Gilbert
Maxwell
Oersted
The property of magnetic materials of retaining magnetism after withdrawal of the magnetizing force is known as
Retentivity
Reluctivity
Resistivity
Conductivity
Mmf in a magnetic circuit corresponds to _____ in an electric circuit
Emf
Voltage drop
Electric Field Intensity
Potential gradient
A negative ion results when an atom gains an additional
Electron
Proton
Neutron
Atom
The magnetic field inside a solenoid
is zero
is uniform
increases with distance from the axis
decreases with distance from the axis
Electron is a Greek word for
amber
Fire
Stone
Heat
The temperature coefficient of resistance of a conductor ______ with an increase in temperature.
increases
decreases
remains the same
becomes negative
If the value of 25 a conductor is 1/255 per oCa then the value of 20is
1/300 per oC
1/250 peroC
1/230 per oC
1/260 per oC
A law that states that the polarity of the induced voltage will oppose the change in magnetic flux causing the induction.
Joule's law
Faraday's law
Coulomb's law
Lenz' law
Temporary magnets are commonly employed in
electric instruments
motors
moving coils loudspeakers
magnetos
Cobalt is an example of a ______ material.
Paramagnetic
Diamagnetic
Ferromagnetic
Non- magnetic
Back emf refers to the
Current equal to the applied emf
Opposing emf
Current opposing the applied emf
Voltage opposing the applied emf
Which of the following materials has the least hysteresis loop area?
soft iron
silicon steel
hard steel
wrought iron
What determines the value of the temperature coefficient of resistance of a material?
length
cross-sectional area
volume
nature and temperature
The core of a transformer heats up when its primary is fed from an ac source because of
permeability
ferromagnetism
reluctance of core
hysteresis loss
The relative permeability of a magnetic material is 10^5. What is its permeability?
4 × 10^5 H/m
4 × 10^-12 H/m
4× 10^-2 H/m
4 × 10^7H/m
The permittivity of a material is given by one of the following formulas.
DE
E/D
D^2/E
D/E
The energy stored in an electrostatic field or electromagnetic field is called
Electromagnetic energy
Kinetic energy
Potential energy
R est energy
The force between two magnetic poles is _____ the relative permeability of the medium.
directly proportional to
independent of
inversely proportional to
equal to
The emf produced in a wire by its motion across a magnetic field does not depend upon the
Diameter of the wire
Length of the wire
Orientation of the wire
Flux density of the field
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
Flux linkages equals
Flux times area of core
Flux times number of turns times area of core
Flux times number of turns times length of core
Flux times number of turns
A good conductor has how many valence electrons?
Magnetic intensity is a
Phasor quantity
Physical quantity
Scalar quantity
Vector quantity
Core materials of a good relay have _________ hysteresis loop.
large
narrow
very large
very narrow
An effect which is generally used in the gausameter to measure flux density.
Skin effect
Magnetic effect
Hall effect
Flywheel effect