Electron is a Greek word for
amber
Fire
Stone
Heat
Correct Answer :
A. amber
Related Questions
Which element has four valence electrons?
Conductor
Insulator
Semiconductor
Semi- insulator
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
If two similar charges 1 coulomb each are placed 1 m apart in aira then the force of repulsion is
8 × 10^6 N
9 × 10 ^9 N
10^6 N
5 × 10^6 N
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 resistance of a material is ____________ its area of cross-section.
directly proportional
independent of
inversely proportional to
equal to
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
Steel is hard to magnetize because of its
Low permeability
High permeability
High density
High retentivity
A theorem which states that an electric current flowing in a circuit produces a magnetic field at external points equivalent to that due to a magnetic shell whose bounding edge is the conductor and whose strength of the current.
Joule's law
Faraday's law
Volta's theorem
Ampere's theorem
What type of bond is formed when there exists some form of collective interactions between the (negatively charged) electrons and (positively charged) nuclei in a solid?
Ionic
Covalent
Metallic
Van der Waals
Refers to the magnetic lines
Flux
Hysteresis
Current
Magnetomotive force
A good conductor has how many valence electrons?
All matters (gasa liquid and solid) are composed of
Neutrons
Particles
Electrons
Atoms
Which of the following has the highest permeability?
Soft iron
Steel
Air
Permalloy
Which of the following is a diamagnetic material?
Aluminum
Silver
Air
Cobalt
One of the solid structures in which the position of the atoms or ions are predetermined
Crystalline solid
Amorphous solid
Polycrystalline solid
Poly amorphous solid
Permeability means
The conductivity of the material for magnetic lines of force
The magnetization test in the material after exciting field has been removed
The strength of an electromagnet
The strength of the permanent magnet
Lenz' law states that the direction of the induced emf and hence current
Is determined by the rate of current flux
Is found by the right hand rule
Is found by the left hand rule
Always opposes the cause producing it
The conduction of electricity across the surface of a dielectric is called
creepage
skin effect
surface effect
crosstalk
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
Permanent magnets can be found in
electric bells
earphones
relays
dy namic loudspeakers
The emf induced in a coil due to the change of its own flux linked with it is called
Mutually induced emf
Dynamically induced emf
Statically induced emf
Self induced emf
The unit of electrical energy is
Joule
Watt- second
Kilowatt hour
All of these
Which of the following has the least number of valence electrons?
Conductor
Semiconductor
Insulator
Semi- insulator
Paramagnetic substance has a relative permeability of
Slightly less than one
Equal to one
Slightly equal to one
Very much greater than one
The phenomenon by which a subtracts pieces of iron
Magnetism
Electromagnetism
Naturalism
Materialism
The permittivity of a material is given by one of the following formulas.
DE
E/D
D^2/E
D/E
When the relative permeability of a material is much greater than 1a it is called _______ material.
diamagnetic
ferromagnetic
paramagnetic
non-magnetic
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
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?
Because air is a gas
Because air has the highest relative permeability
Because air is a conductor of magnetic flux
Because air has the lowest relative permeability
The core of a magnetic equipment uses a magnetic material with
Least permeability
Low permeability
Moderate permeability
High permeability