Q.1
The merger of hole and free electron is called
  • Covalent bonding
  • Recombination
  • Thermal energy
  • Free electrons
Q.2
Electrical contact materials used in switches, brushes, relay must possess
  • High thermal conductivity and high melting point
  • Low thermal conductivity and low melting pointL
  • High thermal conductivity and low melting point
  • Low thermal conductivity and high melting point
Q.3
In an intrinsic semiconductor, at a given temperature T
  • The number of electrons-hole pairs generated per second due to thermal motion are equal to the number of electron-hole pairs lost per second due to recombination
  • The number of electron-hole pairs generated per second due to thermal motion is always less than the number of electron-hole pairs lost per second due to recombination
  • The number of electron hole pairs generated per second due to thermal motion is always more than the number of electron-hole pairs lost per second due to recombination
  • Any of the above
Q.4
The resistance of a photoconductor
  • Increases with increase in light intensity
  • Decreases with increase in light intensity
  • May increase or decrease with increase in light intensity
  • Remains constant
Q.5
Which of the following are true for relative dielectric constant?It is dimensionless.It is equal to 1 for vacuum.It is equal to 1 for all substances.
  • 1 and 2 only
  • 2 and 3 only
  • 1 and 3 only
  • 1, 2 and 3
Q.6
On the basis of the type of chemical bonds, solids may be classified into
  • Ionic crystals
  • Ionic and valence crystals
  • Ionic crystal, valence crystals and metals
  • Ionic crystals, valence crystals, metal and vander wall crystals
Q.7
In van der walls crystals, there exists a high degree of stability of the outer electron shell.
  • True
  • False
Q.8
A vacant electronic state moves in the same direction as would a positive charge carrier.
  • True
  • False
Q.9
In solid insulator materials having only one kind of atom, the types of polarization which exist are
  • Electronic only
  • Electronic and ionic
  • Electronic, ionic and permanent
  • All of above
Q.10
At room temperature the number of conducting electrons in an intrinsic semiconductor
  • Is almost equal to the number of valence electrons
  • Is about half the number of valence electrons
  • Is small as compared to the number of valence electrons
  • Is a very small fraction of the number of valence electrons
Q.11
Schrodinger wave equation is a
  • Linear equation
  • Differential equation
  • Partial differential equation
  • None of the above
Q.12
Spontaneous magnetisation is characteristic of ferromagnetic materials.
  • True
  • False
Q.13
Piezoelectricity means the slight change in dimensions of a specimen when an electric field is applied.
  • True
  • False
Q.14
Debye temperature of metals is
  • About 10 K
  • About 200 K
  • About 600 K
  • About 2 K
Q.15
Electric dipole moment is expressed in debye unit.
  • True
  • False
Q.16
A leakage capacitor can be represented by a capacitance C and resistance R in parallel C.
  • True
  • False
Q.17
Many compounds also exhibit semiconducting properties.
  • True
  • False
Q.18
The rule that resistivity of conductors can be separated into two parts viz. temperature independent and temperature dependent is known as
  • Matthiessen’s rule
  • Debye rule
  • Curie rule
  • Onne’s rule
Q.19
Above a certain temperature, the specific heat of a metal becomes constant. This temperature is called
  • Debye temperature
  • Curie temperature
  • Neel temperature
  • Transition temperature
Q.20
An atom of a rare gas is placed is an electric field E. Then
  • The nucleus will be shifted in the direction of E by an amount which is proportional to E.
  • The nucleus will not be shifted.
  • The nucleus will be shifted in the direction of E by an amount which is independent of E.
  • The nucleus will be shifted in a direction opposite to that of E.
0 h : 0 m : 1 s