The phenomenon by which a subtracts pieces of iron
Magnetism
Electromagnetism
Naturalism
Materialism
Correct Answer :
A. Magnetism
Related Questions
The energy stored in an electrostatic field or electromagnetic field is called
Electromagnetic energy
Kinetic energy
Potential energy
R est energy
The quantity 10^6 maxwells is equivalent to one
Weber
Gauss
Gilbert
Tesla
The greater percentage of materials is _________.
diamagnetic
paramagnetic
ferromagnetic
non-magnetic
______ is an electromagnet with its core in the form of a close magnetic ring.
S olenoid
Paraboloid
Toroid
Cycloid
A magnetizing force of 1000 AT/m will produce a flux density of __________ i
1.257 mWb/m^2
0.63 Wb/m^2
1.257 Wb/m^2
0.63 mWb/m^2
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)
The force between two charges placed a given distance apart ______ as the relative permittivity of the medium is increased.
increases
decreases
remains unchanged
becomes infinite
Magnetic field intensity is a ________ quantity.
scalar
phasor
vector
variable
The core of a magnetic equipment uses a magnetic material with
Least permeability
Low permeability
Moderate permeability
High permeability
Small voltages generated by a conductor with current in an external magnetic field.
Skin effect
Magnetic effect
Hall effect
Flywheel Effect
The direction of force o a current carrying conductor placed in a m found by
Cork screw rule
Fleming's left hand rule
Fleming's right hand rule
using a compass
The B-H curve of ________ is not a straight line.
air
wood
silicon steel
soft iron
The temperature coefficient of resistance of a conductor ______ with an increase in temperature.
increases
decreases
remains the same
becomes negative
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
If the number of valence electrons of an atom is exactly 4a then the substance is called
a semiconductor
a conductor
an insulator
a cryogenic conductor
A magnetic circuit carries a flux iin the iron part and a fluxgin the air gap. What is the leakage coefficient?
i/g
i × g
g/ i
i + g
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
The evaporation of electrons from a heated surface is called
Radiation
Convection
Thermionic emission
Conduction
What revolves about the positive nucleus in a definite orbit?
Atom
Proton
Electron
Neutron
The resistivity of a conductor ___________ with an increase in temperature.
increases
decreases
remains the same
becomes zero
Who discovered that a current-carrying conductor would move when placed in a magnetic field?
Michael Faraday
Andre Ampere
Hans Christian Oersted
Gustav Robert Kirchhoff
Which of the following magnetic materials can be easily magnetized in both direction?
Soft magnetic materials
Hard magnetic materials
High hysteresis loss materials
Low hysteresis loss materials
When a conductor is stationary and the magnetic field is moving or changing the emf induced is called
Statically induced emf
Mutually induced emf
Self induced emf
Dynamically induced emf
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
When a wire loop is rotated in a magnetic field the direction of the induced emf changes one in every _______ revolution
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
Which of the following has the least number of valence electrons?
Conductor
Semiconductor
Insulator
Semi- insulator
An atom or a group of atoms that carries a net electric charge.
Positive ion
Negative ion
Ion
Electron
What is the value of the absolute permittivity of air?
8.854 F/m
8.854 × 10^-12 mF/m
8.854× 10^-12 F/m
8.854 × 10^-12 F/m
If two similar charges 1 coulomb each are placed 1 m apart in aira then the force of repulsion is
8 × 10^6 N
9 × 10 ^9 N
10^6 N
5 × 10^6 N