Physics Practice MCQ Page 49

Multiple Choice questions for Physics in the sets of 10 each on one page with questions and answers. All sets are useful in the preparation of subject tests for employment or admission.
Question: 4045   a quartz crystal is capable of generating ultrasonic waves of frequency
  1. varying directly with the length of the crystal along the optic axis
  2. varying inversely with the length of the crystal along the optic axis
  3. varying directly with the thickness of the thickness of the crystal along the electrical axis
  4. varying inversely with the thickness of the crystal increase of pressure increases the melting point
Question: 4047   the Clausius-Clapeyron equation indicates that the increase of pressure increases the melting point
  1. in the case of all substances
  2. in the case of substances which expand on solidification
  3. in the case of substances which contract on solidification
  4. in the case of substances which neither expand nor contract on solidification
Question: 4048   When the temperature of a gas is increased at constant pressure, the potential energy of molecules
  1. increases but their kinetic energy deceases
  2. decreases but their kinetic energy increases
  3. as well as their kinetic energy decrease
  4. as well as their kinetic energy increase
Question: 4049   The entropy of a thermodynamic system increases, when the system is made use of to convert
  1. heat into work at a constant temperature
  2. heat into work in a cyclic operation
  3. work into heat in a cyclic operation
  4. work into heat at a constant temperature
Question: 4050   The entropy of a gaseous system decreases, when the gas expands
  1. freely, without doing any work
  2. by seepage, without any change in volume
  3. by doing work, isothermally
  4. by doing work, adiabatically
Question: 4052   The phenomenon of viscosity in gases is associated with momentum transport from 'high velocity' region. the mean square velocity of those molecules which participate in the transfer of momentum across a hypothetical layer of the gas is given by
  1. 2 kT/m
  2. 8 kT/m
  3. 3 kT/m
  4. 4 kT/m
Question: 4053   Planck's law for the distribution of energy in the spectrum of black body radiation goes over to Wien's law in the short wavelength region because of the fact that both these laws
  1. assume continuous variation of energy
  2. assume discontinuous variation of energy
  3. use the same expressions for different modes of vibration
  4. lead to very small values for the probability factor
Question: 4054   The vessel containing a gas has a small hole in it causing the gas to leak. When the temperature is increased from 400 K to 900 K the rate of leakage of the gas will
  1. remain the same
  2. increase by a factor 2.25
  3. increase by a factor 1.5
  4. decrease by a factor 0.44
Question: 4056   'Critical temperature' is defined as the
  1. lowest temperature at which the gas can be liquefied at constant pressure
  2. lowest temperature at which the gas can be liquefied by increase of pressure alone
  3. highest temperature at which the gas can be liquefied by increase of pressure alone
  4. highest temperature at which the gas can liquefied at constant pressure
Question: 4057   Two lenses of focal lengths 10 and 20 cm and dispersive power 0.015 and 0.027 respectively will act as an achromatic doublet if they are separated by
  1. 5.5 cm
  2. 10.5 cm
  3. 13.5 m
  4. 18.5 cm
Question: 4058   The points of units angular magnification in a lens assembly are
  1. principal points
  2. focal points
  3. nodal points
  4. conjugate points
Question: 4060   A parallel beam of white light is allowed to fall axially on the slit of a spectrometer. A thin air film between parallel glass plates is placed in front of the slit. There are 250 fringes between 4000A0 and 6500A0. The order of the bright fringe corresponding to 500A0 is
  1. 200
  2. 250
  3. 400
  4. 500