A good conductor has how many valence electrons?
Correct Answer :
B.
Related Questions
What is the SI unit of reluctance?
At
At/m
N/Wb
At/Wb
The unit of flux density is
Wb/m
Tesla
At/m
N/Wb
What is the SI unit of specific resistance or resistivity?
Ohm-circular mil per inch
Ohm-circular mil per foot
Ohm-m
Ohm-cm
When the ferromagnetic substance is inserted in a current- carrying solenoida the magnetic field is
Greatly decreased
Greatly increased
Slightly decreased
Slightly increased
Calculate the flux density that will be produced by the field intensity of 2000 a. t/m for a permeability of 126 x 10^-6 T/A.t/m
0.252 G
0.252 x 10^-2 T
0.252 T
0.252 x 10^-2 G
The permeability of permalloy is
Very much greater than permeability of air
Slightly greater than permeability of air
Slightly less than permeability of air
Equal to the permeability of air
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
Which of the following materials has permeability slightly less than that of free space?
Paramagnetic
Non- magnetic
Ferromagnetic
Diamagnetic
Magnetic fields do not interact with
Moving permanent magnets
Stationary permanent magnets
Moving electric charges
Stationary electric charges
Which of the following is a paramagnetic material?
Carbon
Copper
Bismuth
Oxygen
The physical motion resulting from the forces of magnetic fields is called
Motor action
Rotation
Repulsion
Torque action
The magnetic field of a magnetized iron bar when strongly heated
Becomes weaker
Becomes stronger
Reverses in direction
is unchanged
Hipernik is an alloy containing __________ iron and __________ nickel.
40% ; 60%
60% ; 40%
50% ; 50%
70% ; 30%
What determines the value of the temperature coefficient of resistance of a material?
length
cross-sectional area
volume
nature and temperature
The ability of a material to conduct magnetic flux through it.
Permittivity
Reluctivity
Conductivity
Permeability
One farad equals
1 coulomb/volt
1 newton/coulomb
1 newton-meter
1 volt/second/ampere
The greater percentage of materials is _________.
diamagnetic
paramagnetic
ferromagnetic
non-magnetic
Electric lines of force leave or enter the charge surface at an angle of
30o
45 o
90o
depending upon the angle of launch and entry
If the length and area of cross-section of a wire are doubleda then its resistance
becomes four times
becomes sixteen times
remains the same
becomes two times
One that has magnetic poles produced by internal atomic structure with no external current necessary
Diamagnetic
Permanent magnets
Paramagnetic
Electromagnetic
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
What is the unit of magnetomotive force?
Volt
Tesla
Ampere- turn
Weber
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
Electric field intensity at a point is numerically equal to ________ at that point.
potential gradient
potential difference
dielectric constant
the force
The magnetic flux of 2000 lines is how many Maxwells?
The point in a magnet where the intensity of magnetic lines of force is maximum
Magnetic pole
South pole
North pole
Unit pole
The temperature coefficient of resistance of insulators is
zero
negative
positive
infinite
The force acting on a unit n- pole placed at that point is called
Magnetic field intensity
Electric field intensity
Electromagnetic field intensity
Intensity magnetization
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
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