What is used as the dielectric material in high voltage transformers?
Mica
Paraffin
Porcelain
Oiled paper
Correct Answer :
C. Porcelain
Related Questions
A permanent magnet does not exert a force on
an unmagnetized iron bar
a magnetized iron bar
a moving electric charge
a stationary electric charge
The net electrical charge in an isolated system remains constant. This is known as
Law of conservation of charge
Coulomb's first law
Coulomb's second law
Law of conservation of energy
Referred to as the specific reluctance of a material
Resistivity
Reluctivity
Conductivity
Permeability
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
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
Magnetic intensity is a
Phasor quantity
Physical quantity
Scalar quantity
Vector quantity
Who demonstrated the theory of electromagnetic induction in 1831?
Michael Faraday
Andre Ampere
James Clerk Maxwell
Charles Coulomb
The property of a material which opposes the creation of magnetic flux in it
Resistance
Reluctance
Permeance
Conductance
What bond is formed when electrons in the outermost energy orbits of the atoms are shared between two or more electrons?
Ionic
Covalent
Metallic
Van der Waals
The temperature coefficient of resistance of insulators is
zero
negative
positive
infinite
How much is the flux in Weber in the above problem?
2 x 10^-5
2 x 10^-3
2 x 10^5
2 x 10^3
A group of magnetically aligned atoms is called
Range
Lattice
Domain
Crystal
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
The electric flux density is a ________ quantity.
phasor
vector
scalar
variable
Which of the following has the highest permeability?
Soft iron
Steel
Air
Permalloy
The electrons in the last orbit of an atom are called _______ electrons.
free
valence
bound
thermionic
The electric potential at a point in air due to a charge is 21 V. If the air is replaced by a medium of relative permittivity of 3a then electric potential at that point will be
63 V
21 V
7 V
42 V
Used to maintain strength of magnetic field
Container
Air gap
Keeper
S ource
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
10^-3 Wb/m^2
10^-2 Wb/m^2
10^3 Wb/m^2
0.1 Wb/m^2
The straight line passing through the two poles of magnet is called
Real axis
Cartesian axis
Magnetic axis
Imaginary axis
How many electrons are needed in the valence orbit to give a material's stability?
The simplest type of atom to exist is the ______ atom.
Helium
Hydrogen
Boron
Oxygen
Cobalt is an example of a ______ material.
Paramagnetic
Diamagnetic
Ferromagnetic
Non- magnetic
A current if flowing east along a power line. If the earth's field is neglecteda the direction of the magnetic field below it is
North
South
East
West
Who developed the electromagnetic theory of light in 1862?
Heinrich Rudolf Hertz
Wilhelm Rontgen
James Clerk Maxwell
Andre Ampere
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
Hydrogen is an example of a _____ material.
Paramagnetic
Diamagnetic
Ferromagnetic
N on- magnetic
A positively charged body has
deficit of electrons
excess of neutrons
excess of electrons
deficit of protons
The temperature coefficient of resistance of semiconductors is
positive
zero
negative
infinite
The electric field intensity between the parallel plate air capacitor is 20 N/C. If an insulating slab of relative permittivity 5 is placed between the platesa then electric field intensity will be
20 N/C
100 N/C
4N/C
40 N/C