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Showing 776 to 800 of 3046 questions (page 32 of 122).

776. The grating equation for normal incidence is

A. d sin theta = lambda / n B. d sin theta = n lambda C. sin theta = n d lambda D. d tan theta = n lambda E. d cos theta = n lambda

777. According to Brewster's law, the tangent of the polarizing angle equals

A. the reciprocal of the refractive index B. the critical angle C. the refractive index of the medium D. the wavelength E. unity

778. For two sources to produce a sustained interference pattern, they must be

A. incoherent B. of different frequencies C. of different amplitudes D. perpendicular to each other E. coherent

779. Newton's rings are formed due to interference in

A. a polarizer B. a plane parallel plate C. a diffraction grating D. a wedge shaped air film E. a thick glass block

780. Bending of light around the edges of an obstacle is called

A. refraction B. polarization C. diffraction D. interference E. dispersion

781. The magnifying power of a simple microscope with the image at the near point is

A. d/f B. 1 + f/d C. 1 - d/f D. f/d E. 1 + d/f

782. The least distance of distinct vision for a normal human eye is

A. 10 cm B. 25 cm C. infinity D. 50 cm E. 1 m

783. Light propagates along an optical fibre mainly by

A. polarization B. diffraction C. refraction at the far end D. total internal reflection E. dispersion

784. The resolving power of a telescope increases when

A. the aperture is increased B. the magnification is reduced C. the focal length of the eyepiece is increased D. the aperture is decreased E. the wavelength is increased

785. In a compound microscope, the objective forms an image that is

A. virtual and diminished B. virtual and erect C. real, inverted and magnified D. real and diminished E. at infinity

786. The value of the universal gas constant R in SI units is

A. 62.4 B. 8.314 C. 0.0821 D. 1.987 E. 0.083

787. The first law of thermodynamics is a statement of the conservation of

A. entropy B. mass C. momentum D. energy E. charge

788. For an isothermal expansion of an ideal gas, the change in internal energy is

A. positive B. equal to the heat absorbed times gamma C. equal to the work done D. negative E. zero

789. For one mole of an ideal gas, Cp - Cv equals

A. R C. R/2 D. gamma R E. 2R

790. The efficiency of a Carnot engine operating between temperatures T1 (source) and T2 (sink) is

A. 1 - T2/T1 B. T1/T2 C. T2/T1 D. 1 - T1/T2 E. T1 - T2

791. A Carnot engine works between 500 K and 300 K. Its efficiency is

A. 80% B. 60% C. 30% D. 40% E. 20%

792. In an adiabatic process

A. internal energy remains constant B. volume remains constant C. temperature remains constant D. pressure remains constant E. no heat enters or leaves the system

793. For any spontaneous natural process, the entropy of the universe

A. becomes negative B. decreases C. increases D. remains constant E. becomes zero

794. The value of the Coulomb constant 1/(4 pi epsilon_0) in SI units is about

A. 9 x 10^9 B. 1.6 x 10^-19 C. 8.85 x 10^-12 D. 3 x 10^8 E. 6.63 x 10^-34

795. The electric field intensity inside a hollow charged conductor in electrostatic equilibrium is

A. infinite B. zero C. uniform and non-zero D. equal to the surface field E. maximum

796. The capacitance of a parallel plate capacitor with plate area A and separation d in vacuum is

A. epsilon_0 d / A B. epsilon_0 A d C. epsilon_0 A / d D. A d / epsilon_0 E. d / epsilon_0 A

797. Three capacitors of 3 microfarad each are connected in series. The equivalent capacitance is

A. 3 microfarad B. 6 microfarad C. 9 microfarad D. 0.33 microfarad E. 1 microfarad

798. The energy stored in a capacitor of capacitance C charged to potential difference V is

A. CV2 B. (1/2)CV C. CV D. (1/2)CV2 E. C2V

799. Inserting a dielectric slab between the plates of a capacitor at constant charge

A. increases the potential difference B. has no effect C. decreases the capacitance D. increases the capacitance E. increases the electric field

800. Gauss's law relates the electric flux through a closed surface to

A. the field at the surface only B. the potential at the centre C. the volume enclosed D. the surface area E. the charge enclosed

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