______ is an electromagnet with its core in the form of a close magnetic ring.
S olenoid
Paraboloid
Toroid
Cycloid
Correct Answer :
C. Toroid
Related Questions
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
Calculate the permeability (in T/A. t/m) of a magnetic material that has a relative permeability of 300
3.78 x 10^4
3.78 x 10^-5
3.78 x 10^-3
3.78 x 10^-6
Referred to as the specific reluctance of a material
Resistivity
Reluctivity
Conductivity
Permeability
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
The branch of Engineering which deals with the magnetic effect of electric current is known as
Magnetism
Electromagnetism
Electrical engineering
Electronics engineering
All magnetic field originates from
moving electric charge
Iron atoms
Magnetic domain
Permanent magnets
__________ is a substance of whose molecules consist of the same kind of atom.
Mixture
Compound
Element
Isotope
One oersted (Oe) is equivalent to _____ Gb/cm.
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
The quantity of magnetism retained by a magnetic material after withdrawal of the magnetizing force is called
Leftover magnetism
Hysteresis
Residual magnetism
Coercivity
The simplest type of atom to exist is the ______ atom.
Helium
Hydrogen
Boron
Oxygen
If the relative permittivity of a material is 10a then its permittivity is
4 × 10^7F/m
4 × 10^-6 F/m
8.854× 10^-11 F/m
8.854 × 10^-12 F/m
Electronic current in a wire is the flow of ____________ electrons.
free
valence
bound
loose
Which of the following is a paramagnetic material?
Carbon
Bismuth
Copper
Oxygen
When the relative permeability of a material is slightly less than 1a it is called _____ material.
diamagnetic
ferromagnetic
paramagnetic
non-magnetic
What is used as the dielectric material in high voltage transformers?
Mica
Paraffin
Porcelain
Oiled paper
When a current carrying conductor is placed in a magnetic fielda the maximum force will act on the conductor when the conductor is at an angle of _______ to the magnetic field.
45o
60o
30o
90o
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
A group of magnetically aligned atoms is called
Range
Lattice
Domain
Crystal
If the number of valence electrons of an atom is less than 4a the substance is called
a conductor
a semiconductor
an insulator
a superconductor
The contribution to the ionization in an ionization chamber by electrons liberated from t he walls.
Skin effect
Walt effect
Hall effect
Edison effect
Materials that have very high permeabilities (hundreds and even thousands times of that of free space)
Paramagnetic
Non- magnetic
Ferromagnetic
Diamagnetic
Flux linkages equals
Flux times area of core
Flux times number of turns times area of core
Flux times number of turns times length of core
Flux times number of turns
The temperature coefficient of resistance of conductors is
positive
zero
negative
infinite
A magnetic field is
The current flow through space around a permanent magnet
The force set up when current flows through a conductor
The force that drives current through a resistor
The force between the plates of a charged capacitor
Whenever a conductor cuts magnetic fluxa an emf is induced in it. This is known as
Coulomb's law
Joule's law
Faraday's law
Ohm's law
One weber of flux is equal to _______ magnetic lines of force.
10^6
10^10
4 × 10^7
10^8
Permeability means
The conductivity of the material for magnetic lines of force
The magnetization test in the material after exciting field has been removed
The strength of an electromagnet
The strength of the permanent magnet
What is the unit of reluctance?
Maxwell
Gauss
At/Wb
Weber
What revolves about the positive nucleus in a definite orbit?
Atom
Proton
Electron
Neutron