Temporary magnets are commonly employed in
electric instruments
motors
moving coils loudspeakers
magnetos
Correct Answer :
B. motors
Related Questions
As the magnetic intensity decreasesa the relative permeability of a magnetic material
decreases
remains the same
increases
becomes zero
The mass of proton is __________ the mass of an electron.
equal to
about 1837 times
less than
200 tim es
An alloy of 40 percent iron and 60 percent nickel.
Alnico
Permalloy
Hipernik
Manganin
One weber of flux is equal to _______ magnetic lines of force.
10^6
10^10
4 × 10^7
10^8
Lenz's law is the consequence of the law of conservation of
Energy
Charge
Field lines
Momentum
Who demonstrated the theory of electromagnetic induction in 1831?
Michael Faraday
Andre Ampere
James Clerk Maxwell
Charles Coulomb
The magnetic field inside a solenoid
is zero
is uniform
increases with distance from the axis
decreases with distance from the axis
If the value of 0 a conductor is 1/234 per oCa then the value of 18is
1/218 per oC
1/252 peroC
1/272 per oC
1/273 per oC
What is the SI unit of conductance?
Siemens
Mhos
Ohms
1/Ohms
The temperature coefficient of resistance of a conductor ______ with an increase in temperature.
increases
decreases
remains the same
becomes negative
What is the usual value of leakage coefficient for electrical machines?
0.5 to 1
1 to 5
5 to 10
1.15 to 1.25
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
The branch of Engineering which deals with the magnetic effect of electric current is known as
Magnetism
Electromagnetism
Electrical engineering
Electronics engineering
Used to maintain strength of magnetic field
Container
Air gap
Keeper
S ource
A test charge means a charge of
-1 C
1 electron
+1 C
-20 C
The greater percentage of materials is _________.
diamagnetic
paramagnetic
ferromagnetic
non-magnetic
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
Hydrogen is an example of a _____ material.
Paramagnetic
Diamagnetic
Ferromagnetic
N on- magnetic
Mmf in a magnetic circuit corresponds to _____ in an electric circuit
Emf
Voltage drop
Electric Field Intensity
Potential gradient
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
The B-H curve of ________ is not a straight line.
air
wood
silicon steel
soft iron
The force between two magnetic poles varies with the distance between them. The variation is ______ to the square of that distance.
Equal
Greater than
Directly proportional
Inversely proportional
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
A group of magnetically aligned atoms is called
Range
Lattice
Domain
Crystal
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
If a 20 V potential is applied across a relay coil with 50 turns having 1 ? of resistancea the total magnetomotive producing magnetic flux in the circuit is
10 Wb
50 T
1000 A t/m
1000,t
Hipernik is an alloy containing __________ iron and __________ nickel.
40% ; 60%
60% ; 40%
50% ; 50%
70% ; 30%
The property of a material which opposes the creation of magnetic flux in it
Resistance
Reluctance
Permeance
Conductance
The ability of a mechanically stressed ferromagnetic wire to recognize rapid switching of magnetization when subjected to a dc magnetic field.
Wartheim effect
Wiedemann effect
Wiegand effect
Edison effect
Magnetic field intensity is a ________ quantity.
scalar
phasor
vector
variable