Which of the following is used by permanent magnets as the magnetic material?
iron
nickel
soft steel
hardened steel
Correct Answer :
D. hardened steel
Related Questions
The total number of magnetic lines of force in a magnetic field is called
Magnetic flux
Magnetic flux density
Magnetic flux intensity
Magnetic potential
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
Electric field intensity at a point is numerically equal to ________ at that point.
potential gradient
potential difference
dielectric constant
the force
What solid has no defined crystal structure except perhaps in the arrangement of the nearest neighboring atoms or ions?
Crystalline
Amorphous
Polycrystalline
Poly amorphous
In electro-mechanical conversion devices like generators and motors the reason why a small air gap is left between the rotor and stator is to
permit mechanical clearance
increase flux density in air gap
decrease the reluctance of magnetic path
complete the magnetic path
What bond is formed when one or more electrons in the outermost energy orbit of an atom are transferred to another?
Ionic
Covalent
Metallic
Van der Waals
Hysteresis loss can be reduced by one of the following.
Increasing mmf of the circuit
Using material narrow hysteresis loop
Using ferromagnetic core
Laminating the magnetic circuit
What is the measure of the density and sign of the electric charge at a point relative to that at some time?
Electric potential
Electric charge
Electric current
Electric intensity
The property of a material which opposes the creation of magnetic flux in it
Resistance
Reluctance
Permeance
Conductance
The temperature coefficient of resistance of semiconductors is
positive
zero
negative
infinite
What is the maximum number of electrons that can be accommodated in the last orbit of an atom?
The lagging effect between flux density of the material and the magne
Permeance
Eddy current
Hysteresis
R eluctance
The magnetic flux of 2000 lines is how many Maxwells?
A factor used to correct for the electrostatic forces of the more distant ions in an ionic solid.
Avogadro's number
Planck's constant
Boltzmann's constant
Madelung constant
Electric field intensity is a ________.
scalar
phasor
vector
variable
If the solenoid is gripped by the right hand with the fingers pointing the direction of current flowa the outstretched thumb will then point the north pole. This is known as
Right hand rule
Helix rule
End rule
Cork screw rule
Define as that pole which when placed in air from a similar and equal pole repels it with a force of newtons
North pole
South pole
Unit pole
Magnetic pole
Defined as the ratio of the volume occupied by the atoms or ions in a unit cell divided by the volume of the unit cell and is used to measure the compactness of a crystal.
Atomic packing factor (APF)
Ionic Packing Ratio (IPR)
Atomic compacting factor (ACF)
Ionic compacting ratio (ICR)
One ampere- turn is equivalent to _____ gilberts
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
Bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions
Ionic bond
Covalent Bond
Electrostatic Bond
Metallic bond
The quantity of magnetism retained by a magnetic material after withdrawal of the magnetizing force is called
Leftover magnetism
Hysteresis
Residual magnetism
Coercivity
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
If the magnetic material is located within a coil through which alternating current (60 Hz frequency) flowsa then __________ hysteresis loops will be formed
What is the main advantage of temporary magnets?
The magnetic flux can be changed.
Hysteresis can be decreased.
Magnetic materials can be used.
Abundance of ferromagnetic material that can be temporarily magnetized.
When the relative permeability of a material is slightly less than 1a it is called _____ material.
diamagnetic
ferromagnetic
paramagnetic
non-magnetic
Formed when there exist distant electronic interactions between (opposite) charges present in the neighboring atoms or molecules.
Ionic bond
Covalent bond
Metallic bond
Van der Waals bond
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
What determines the value of the temperature coefficient of resistance of a material?
length
cross-sectional area
volume
nature and temperature
Defined as the number of lines per unit area through any substance in a plane at right angles to the lines of force
Flux
Flux lines
Flux density
Flux intensity