A completely filled band is called
1.Conduction band
2.Valence band
3.Forbidden band
4.Core band
A ferromagnet will become fully magnetized at
1.High voltage A.C
2.Low voltage A.C
3.Alternating current at its peak value
4.D.C current at peak value
A vacant or partially filled band is called
1.Conduction band
2.Valence band
3.Forbidden band
4.Empty band
A wire is stretched by a force F which causes an extension 1. The energy stored in the wire is
1.The extension of the wire is proportional to the force applied
2.The weight of the wire is negligible
3.The wire is not stretched beyond its elastic limit
4.The cross sectional area of the wire remains constant
A wire obeys Hooks law is of length 11 when it is in equilibrium under a tension F1. Its length becomes 12 when the tension is increased to F2. The energy stored in the wire during this process is
1.(F1+F2) (121+122)
2.(F1+F2) (122-112)
3.(F1+F2) (12-11)
4.(F1+F2) (12-11)
Any alteration produced in shapes length or volume when a body is subjected to some external force is called
1.Stiffness
2.Toughness
3.Extension
4.Deformation
Bracket series is obtained when all transition of electron terminate on
1.4th orbit
2.5th orbit
3.3rd orbit
4.2nd orbit
Coercive force is the force which opposes
1.Demagnetization
2.Breakage
3.Extension
4.Surface cracking
Energy needed to magnetize and demagnetize is represented by
1.Hysteresis curve
2.Hysteresis loop area
3.Hysteresis loop
4.Straight line
Excited atoms return to their ground state in
1.10-10s
2.10-8s
3.10-6s
4.10-9s
Formation of large molecule by joining small molecules is
1.Fusion
2.Polymerization
3.Crystallization
4.Subtraction
Ground state energy of the 4th orbit in a H-atom is
1.?13.60 eV
2.?3.40 eV
3.?0.85 eV
4.?1.51 eV
Holes can exist in
1.Conductors
2.Insulators
3.Semi conductors
4.All of the above
Hydrogen atom does not emit X-rays because
1.its energy levels are too close to each other
2.its energy levels are too far apart
3.it is too small in size
4.it has a single electron
If the density of atoms remain same along any direction in a crystal is called
1.Symmetry
2.Homogeneity
3.Isotropy
4.Cleavage
In a semiconductors the charge carriers are
1.Holes only
2.Electrons only
3.Electron and holes both
4.All of the above
In an electronic transition atom cannot emit
1.?-rays
2.infra red radiation
3.visible light
4.ultraviolet rays
In hydrogen spectrum which one of the following series lies in the ultraviolet region?
1.Balmer series
2.Pfund series
3.Bracket series
4.Lymann series
In obtaining an X-ray photograph of our hand we use the principle of
1.photo electric effect
2.ionization
3.shadow photograph
4.any of above
In simple cube one atom or molecule lies at its
1.Force corners
2.Nine corners
3.Eight corners
4.Six corners
Many of the semi conductors are crystals of the type
1.Face centred cubic
2.Body centred cubic
3.Simple cubic
4.All of the above
Materials in which valence electrons are tightly bound to their atoms at low temperature are called
1.Semi conductor
2.Super conductors
3.Insulators
4.Conductor
Materials that undergo plastic deformation before breaking are called
1.Brittle
2.Ductile
3.Amorphous
4.Polymers
On the basis of band theory of solids the semiconductors have
1.A party filled valence band and totally empty conduction band
2.A completely filled valence band a totally empty conduction band and a very wide forbidden band
3.A completely filled valence band a partially filled conduction band and a narrow forbidden band
4.A partly filled valence band a totally empty conduction band and a wide forbidden band
Photon of highest frequency will be absorbed when transition takes place from
1.1st to 5th orbit
2.2nd to 5th orbit
3.3rd to 5th orbit
4.4th to 5th orbit
Radiation with wavelength longer than red lights
1.ultraviolet rays
2.X-rays
3.infra red radiation
4.visible radiation
Ratio of the weight of H-atom to that of an electron is approximately
1.18.336
2.1836
3.18360
4.183.6
Reverse process of photoelectric effect is
1.pair production
2.Compton effect
3.annihilation of matter
4.X-rays production
The angular position of cells remains the same for a sample of a crystal. This property is called
1.Isotropy
2.Cleavage
3.Homogeneity
4.The external symmetry of form
The band theory of solids explains satisfactorily the nature of
1.Electrical insulators alone
2.Electrical conductors alone
3.Electrical semi conductors alone
4.All of the above
The breaking of crystals along definite direction is called
1.Cleavage
2.Symmetry
3.Isotropy
4.Homogeneity
The bulk properties of materials such as their mode of fracture can be related to their
1.Polymerization
2.Cleavage
3.Microstructure
4.Dislocation
The curie temperature is that at which
1.Semi-conductor becomes conductors
2.Ferromagnetic becomes paramagnetic
3.Paramagnetic becomes diamagnetic
4.Metals become super conductor
The electric P.E of an electron in an orbit at a distance rn from the positive charge
1.Ke2/rn
2.Ke2/rn2
3.?Ke2/rn
4.?Ke2/rn2
The electrons in conduction band are free to
1.Transport vibrations
2.Transport signals
3.Transport charge
4.Transport impulses
The energy band occupied by the valence electrons is called
1.Energy state
2.Valence band
3.ve energy state
4.conduction band
The net charge on n-type material is
1.Positive
2.Negative
3.Both positive and negative
4.Neutral
The penetrating power of X-rays depends on their
1.applied voltage
2.frequency
3.source
4.all of the above
The radiations emitted form hydrogen filled discharge tube show
1.band spectrum
2.line spectrum
3.continuous spectrum
4.absorption spectrum
The ration stress to strain in youngs modulus of the material then tension is
1.Directly proportional to extension.
2.Directly proportional to strain.
3.Directly proportional to square of amplitude.
4.Inversely proportional to extension
Tick the correct statement
1.an atom has limited number of ionization potentials but a large number of excitation potentials
2.there are as many excitation potentials as there are excited states
3.the difference between the energy of the ground sate and any one of the excited states is the measure of excitation energy
4.all of above
Total number of series in hydrogen spectrum is
1.three
2.four
3.five
4.six
Very weak magnetic fields are detected by
1.Squids
2.Magnetic resonance imaging (MRI)
3.Magnetometer
4.Oscilloscope
When we excite some atoms by heat collision or electrical discharge they will
1.radiate electromagnetic energy with a continuous distribution of wavelength
2.absorb particular wavelengths when white light is incident on them
3.radiate electromagnetic energy of discrete characteristic wavelength
4.emit either invisible or visible light
When X-rays are passed through successive aluminum sheets what happens to their thickness?
1.increases
2.it decreases
3.it remains same
4.sometimes increases and sometimes decreases
Which one has the greatest energy gap ?
1.Semi conductor
2.Conductor
3.Metals
4.Non metals
Which one of following postulate is in accordance with the Rutherfords model?
1.continuous spectra for atoms
2.discrete spectra for atoms
3.either continuous nor discrete
4.no spectrum
With increase in temperature the electrical conductivity of intrinsic semi conductor
1.Decreases
2.Increases
3.Remains same
4.First increases then decreases
X-ray are
1.of unknown nature
2.high energy electrons
3.high energy photons
4.radio isotopes
X-rays are similar in nature to
1.cathode rays
2.positive rays
3.?-rays
4.?-rays