Which of the following is a natural magnet?
Steel
Magnesia
Lodestone
S oft iron
Correct Answer :
C. Lodestone
Related Questions
A 6- V battery is connected across a solenoid of 100 turns having a resistance of 2 ?a Calculate the number of ampere turns?
The magnetic potential in a magnetic circuit can be measured in terms of
Mmf
Emf
Farad
Coulomb
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
Flux density is measured in
Tesia
Weber
Ampere- turn
Maxwell
What is the SI unit of specific resistance or resistivity?
Ohm-circular mil per inch
Ohm-circular mil per foot
Ohm-m
Ohm-cm
Electrons at the outer shell are called
Outer shell electrons
Inner shell electrons
Semiconductor electrons
Valence electrons
An alloy of 22 percent iron and 78 per cent nickel.
Permalloy
Alnico
Constantan
M anganin
The force between two magnetic poles is _______ their pole strengths.
directly proportional to
the sum of
inversely proportional to
the product of
Who discovered superconductivity in 1911?
Kamerlingh Onnes
Alex Muller
GeoryBednorz
Charles Coulomb
The magnetic energy stored in an inductor is ______ current.
Directly proportional to
Inversely proportional to
Directly proportional to the square of
Inversely proportional to the square of
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
At/m is a unit of
mmf
magnetic force
reluctance
magnetic flux density
Hipernik is an alloy containing __________ iron and __________ nickel.
40% ; 60%
60% ; 40%
50% ; 50%
70% ; 30%
A good conductor has how many valence electrons?
The amount of magnetizing force to counter balance the resid magnetic material is referred to as
Reluctivity
Susceptivity
Coercivity
Retentivity
Bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions
Ionic bond
Covalent Bond
Electrostatic Bond
Metallic bond
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
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 straight line passing through the two poles of magnet is called
Real axis
Cartesian axis
Magnetic axis
Imaginary axis
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
A magnetic flux of 2.5 x10^4 Wb through an area of 5 x10^4 square meters results in
5 Wb
0.5 Tesia of flux density
5x 10^-5 Wb of flux
5000 Tesia of flux density
The tiniest element of matter
Atom
Proton
Electron
Neutron
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
Electronic current in a wire is the flow of ____________ electrons.
free
valence
bound
loose
A one cubic cm of copper has how many free electrons at room temperature?
80 × 10^18
8.5 × 10^22
20 × 10^10
50 × 10^20
What is the typical saturation flux density for most magnetic materials?
4 Wb/m^2
5 Wb/m^2
1 Wb/m^2
2 Wb/m^2
A negatively charge body has
deficit of electrons
excess of protons
excess of electrons
deficit of neutrons
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 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
Temporary magnets are commonly employed in
electric instruments
motors
moving coils loudspeakers
magnetos