The reluctance of a magnetic circuit varies with
length × area
area � length
length � area
length + area
Correct Answer :
C. length � area
Related Questions
The unit of flux density is
Wb/m
Tesla
At/m
N/Wb
If the number of valence electrons of an atom is less than 4a then the substance is probably
a metal
an insulator
a non-metal
a semiconductor
Which of the following materials has the highest dielectric strength?
Glass
Oiled paper
Mica
Air
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.
The temperature coefficient of resistance of conductors is
positive
zero
negative
infinite
Small voltages generated by a conductor with current in an external magnetic field.
Skin effect
Magnetic effect
Hall effect
Flywheel Effect
Amorphous solid is also called
Crystalline
Non- crystalline
Polycrystalline
Homogenous
The emf produced in a wire by its motion across a magnetic field does not depend upon the
Diameter of the wire
Length of the wire
Orientation of the wire
Flux density of the field
The science of adapting electronics to aerospace flight.
Avionics
Aerotronics
Aerodynamics
Astrionics
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
The permeability of a material having a flux density of 5 Wb/m^2 is 10^-5 H/m. What is the value of magnetizing force?
5 × 10^-5 N/Wb
500 × 10^3 N/Wb
4 × 10^7N/Wb
4 × 10^7N/Wb
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
The magnetic field around the conductor is determined by the
Size of the conductor
Amount of current
Current divided by the resistance
Resistance divided by the current
Under ordinary conditionsa a body is considered
positively charged
neutral
negatively charged
stable
When the ferromagnetic substance is inserted in a current- carrying solenoida the magnetic field is
Greatly decreased
Greatly increased
Slightly decreased
Slightly increased
The potential at a point due to a charge is 15 V. If the distance is times, the potential at the point will be
5 V
18 V
45 V
15 V
A good conductor has how many valence electrons?
The unit of flux is _____ in cgs system.
Tesia
Gilbert
Maxwell
Oersted
Electromotive force in a circuit
causes free electrons to flow
increases the circuit resistance
maintains circuit resistance
is needed to make the circuit complete
Gases whose particles are charged are known as
Conductors
Insulators
Gaseous Conductors
Plasma
The relation between absolute permittivity of air ( 0)a absolute p and velocity of light (c) is given by
0 0= c^2
0 0= c
1/ 0 0= c
1/ 0 0= c^2
A principle that states that only two electrons with different spins are allowed to exist in a given orbit
Bohr's principle
Pauli exclusion principle
Avogadro's principle
Coulomb's principle
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
If the right handed bottle-opener cork screw is assumed to be along the conductor so as to advance in the direction of current flow, the motion of its handle will indicate the direction of magnetic flux produced around the conductor. This is known as
Right hand rule
Left hand rule
Cork screw rule
End rule
Electric potential is a _______ quantity.
scalar
phasor
vector
variable
Three charges of +5 Ca -6 C and +9 C are placed inside a sphere. What is the total flux passing through the surface of sphere?
8 C
14 C
20 C
-6 C
The contribution to the ionization in an ionization chamber by electrons liberated from t he walls.
Skin effect
Walt effect
Hall effect
Edison effect
Ohm's law cannot be applied to which material?
Copper
Silver
Silicon carbide
Aluminum
The force acting on a pole of 5 Wb is 25 N. What is the intensity of the magnetic field?
5 N/Wb
25 N/Wb
125 N/Wb
0.2 N/Wb
The quantity of magnetism retained by a magnetic material after withdrawal of the magnetizing force is called
Leftover magnetism
Hysteresis
Residual magnetism
Coercivity