Which element has four valence electrons?
Conductor
Insulator
Semiconductor
Semi- insulator
Correct Answer :
C. Semiconductor
Related Questions
The emission of electrons from hot bodies is called
Radiation effect
Edison effect
Skin effect
Half effect
When the current flowsa the magnetic field ��. conductor is in what direction?
The same as the current direction
Opposite the current direction
Omnidirectional
In the direction determined by the left hand rule
Electrons at the outer shell are called
Outer shell electrons
Inner shell electrons
Semiconductor electrons
Valence electrons
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 point in a magnet where the intensity of magnetic lines of force is maximum
Magnetic pole
South pole
North pole
Unit pole
The reluctance of the magnetic circuit is ________ relative permeability of the material comprising the circuit.
directly proportional to
inversely proportional to
independent of
dependent of
At/m is a unit of
mmf
magnetic force
reluctance
magnetic flux density
A magnetic material losses its ferromagnetic properties at a point called
Curie temperature
Inferred absolute temperature
Room temperature
Absolute temperature
States that the ratio of the thermal conductivity is proportional to the absolute temperature for all metals.
Wien's displacement law
Hartleys law
Hall's law
Wiedemann Franz law
What is the SI unit of conductivity?
Ohms/m
Ohms-m
Siemens-m
Siemens/m
Electron is a Greek word for
amber
Fire
Stone
Heat
The hot resistance of an incandescent lamp is about _______ its cold resistance.
10 times
100 times
5 times
50 times
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
A germanium atom has an atomic weight of72. How many neutrons are there?
The unit of electrical energy is
Joule
Watt- second
Kilowatt hour
All of these
The property of a material which opposes the creation of magnetic flux in it
Resistance
Reluctance
Permeance
Conductance
The magnetic potential in a magnetic circuit can be measured in terms of
Mmf
Emf
Farad
Coulomb
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
Which of the following is used by temporary magnets as the magnetic material?
Hardened steel
Cobalt steel
Soft iron
Tungsten steel
Electromotive force in a circuit
causes free electrons to flow
increases the circuit resistance
maintains circuit resistance
is needed to make the circuit complete
Referred to as the specific reluctance of a material
Resistivity
Reluctivity
Conductivity
Permeability
The permittivity of a material is given by one of the following formulas.
DE
E/D
D^2/E
D/E
Electronic current in a wire is the flow of ____________ electrons.
free
valence
bound
loose
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
It is the reciprocal of reluctance and implies the case of readiness with which magnetic flux is developed.
R esistance
Conductance
Permeance
I nductance
Which of the following is a vector quantity?
Magnetic potential
Magnetic field intensity
Magnetic permeability
F lux density
A positively charged body has
deficit of electrons
excess of neutrons
excess of electrons
deficit of protons
How many neutrons does a copper atom have?
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 quantity of magnetism retained by a magnetic material after withdrawal of the magnetizing force is called
Leftover magnetism
Hysteresis
Residual magnetism
Coercivity