A magnetic material losses its ferromagnetic properties at a point called
Curie temperature
Inferred absolute temperature
Room temperature
Absolute temperature
Correct Answer :
A. Curie temperature
Related Questions
The simplest type of atom to exist is the ______ atom.
Helium
Hydrogen
Boron
Oxygen
A t/m is a unit of
Mmf
Emf
Reluctance
Magnetizing force
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
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
Core materials of a good relay have _________ hysteresis loop.
large
narrow
very large
very narrow
The reluctance of a magnetic circuit varies with
length × area
area � length
length � area
length + area
The amount of magnetizing force to counter balance the resid magnetic material is referred to as
Reluctivity
Susceptivity
Coercivity
Retentivity
Referred to as the specific reluctance of a material
Resistivity
Reluctivity
Conductivity
Permeability
How many neutrons does a copper atom have?
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
Which of the following materials has the least hysteresis loop area?
soft iron
silicon steel
hard steel
wrought iron
The permittivity of a material is given by one of the following formulas.
DE
E/D
D^2/E
D/E
The ratio between the intensity of magnetization produced in a substance to the magnetizing force producing it
Magnetic Reluctivity
Magnetic Resistivity
Magnetic susceptibility
Magnetic conductivity
Which of the following is a diamagnetic material?
Aluminum
Silver
Air
Cobalt
What is the SI unit of reluctance?
At
At/m
N/Wb
At/Wb
The magnetic field of a bar magnet most closely resembles the magnetic field of
a horseshoe magnet
a straight current- carrying wire
a stream of electrons moving parallel to one another
a current- carrying wire loop
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 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
One that has magnetic poles produced by internal atomic structure with no external current necessary
Diamagnetic
Permanent magnets
Paramagnetic
Electromagnetic
__________ is a substance of whose molecules consist of the same kind of atom.
Mixture
Compound
Element
Isotope
One electron volt (1 eV) is equivalent to _____ joules
1.3 x 10^-19
1.4 x 10^-19
1.5 x 10^-19
1.6 x 10^-19
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
The ratio of the permeability of material to the permiabiity of air or vacuum.
Relative permeability
Relative permittivity
Relative conductivity
Relative reluctivity
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
A negatively charge body has
deficit of electrons
excess of protons
excess of electrons
deficit of neutrons
The quantity 10^6 maxwells is equivalent to one
Weber
Gauss
Gilbert
Tesla
What is the practical unit of electrical energy?
Watt
Kilowatt-hour
Kilowatt-second
Megawathour
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
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
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