CHAPTER 9:Physical Optics

(1)               Optical active crystals rotates the

(a)          Vibrating plane

(b)         polarization plane

(c)          diffraction plane

(d)         interference plane

(2)               Which is not optically active?

(a)          sugar

(b)         tartaric acid

(c)          water

(d)         sodium chlorate

(3)               I double slit experiment, we observe

(a)    Interference fringes only

(b)    Diffraction fringes only

(c)    Both interference and diffraction fringes

(d)    Polarized fringes

(4)               When light incident normally on thin film, the path difference depends upon

(a)    Thickness of the film only

(b)    Nature of the film only

(c)    Angle of incidence only

(d)    All thickness, nature and angle of incidence

(5)               Which one of the following properties of light does not change with the nature of the medium?

(a)    Velocity

(b)    Wavelength

(c)    Amplitude

(d)    Frequency

(6)               Light reached the earth from sun in nearly

(a)    15 minutes

(b)    10 minutes

(c)    8 minutes

(d)    8 minutes 30 seconds

  

(7)               Photoelectric effect was given by

(a)    Hertz

(b)    Fresnel

(c)    Einstein

(d)    Plank

(8)               According to Einstein, light travels from one place to another in the

form of

(a)    waves

(b)    particles

(c)    photons

(d)    it was not his discovery

(9)               Longitudinal waves do not exhibit

(a)    Reflection

(b)    Refraction

(c)    Diffraction

(d)    Polarization

(10)           Central spot of Newton’s rings

(a)    Bright

(b)    Dark for large wavelength

(c)    Dark

(d)    Bright for large wavelength

(11)           A point source of light placed in a homogeneous medium gives

rise to

(a)    A cylindrical wave front

(b)    An elliptical wave front

(c)    A spherical wave front

(d)    A plane wave front

(12)           the locus of all points in a medium having the same phase of vibration is called

(a)    crest

(b)    trough

(c)    wavelength

(d)    wave front

(13)           Which one of the following is nearly monochromatic light?

(a)    Light form fluorescent tube

(b)    Light form sodium lamp

(c)    Light form neon lamp

(d)    Light form simple lamp

(14)           Two sources of light are coherent if they emit rays of

(a)    Same wavelength

(b)    Same amplitude of vibration

(c)    Sam wave length with constant phase difference

(d)    Same amplitude and wavelength

(15)           When crest of one wave falls over the trough of the other wave, this phenomenon is known as

(a)    Polarization

(b)    Constructive interference

(c)    Destructive interference

(d)    Diffraction 

(16)           In Young’s double slit experiment, the fringe spacing is equal to

(a)    dλD

(b)    2λd/D

(c)    λD/d

(d)    λd/D

(17)           In Young double slit experiment, if white light is used

(a)    Alternate dark and bright fringes will be seen

(b)    Coloured fringes will be seen

(c)    No interference fringes will be seen

(d)    Impossible to predict

(18)           The Velocity of light was determined accurately by

(a)    Newton

(b)    Michelson

(c)    Huygen

(d)    Young

(19)           The condition for constructive interference of two coherent beams is that the path difference should be

(a)    Integral multiple of λ/2

(b)    Integral multiple of λ

(c)    Odd Integral multiple of λ/2

(d)    Even integral multiple of λ

(20)           In an interference pattern

(a)    Bright fringes are wider than dark fringes

(b)    Dark fringes are wider than bright fringe

(c)    Both dark and bright fringes are of equal width

(d)    Central fringes are brighter than the outer fringes

(21)           The appearance of Colour in thin films is due to

(a)    Diffraction

(b)    Dispersion

(c)    Interference

(d)    Polarization

(22)           The blue to the sky is due to

(a)    Diffraction

(b)    Reflection

(c)    Polarization

(d)    Scattering

(23)           A light ray traveling form rarer to denser medium suffers a phase change

of

(a)    60^o

(b)    90 ^o

(c)    180 ^o

(d)    45 ^o

(24)           When one mirror of a Michelson Interferometer is moved a distance of 0.5 mm, we observe 2000 fringes. What will be wavelength of light used ?

(a)    5000 nm

(b)    5000 A^o

(c)    500 m

(d)    2000 μm

  

(25)           Diffraction effect is

(a)    More for a round edge

(b)    Less for a round edge

(c)    More for a sharp edge

(d)    Less for a sharp edge

(26)           The wavelength of X-rays is of the order of

(a)    10A^o

(b)    1000A^o

(c)    1A^o

(d)    100A^o

(27)           Wavelength of X-rays falling at glancing angle of 30^o on a crystal with atomic spacing 2x10^-10 for the first order diffraction is

(a)    4x10^-10 m

(b)    2x10^-10 m

(c)    0.02 x 10^-10m

(d)    20x10^-10m

(28)           A diffraction grating has 500 lines per mm. its slit spacing or grating element will be equal to

(a)    500 mm

(b)    5x10^-3mm

(c)    2x10^-5mm

(d)    2x10^-3mm

(29)           In a plane polarized light,

(a)    Vibration in all direction

(b)    Vibration in two mutually perpendicular directions

(c)    Vibration take place in a direction perpendicular to the direction of propagation of light.

(d)    No vibration at all.

(30)           Light on passing through a Polarized is

(a)    Plane polarized

(b)    Un-polarized

(c)    Circularly polarized

(d)    Elliptically polarized

(31)           Which one of the following cannot be polarized?

(a)    Radio waves

(b)    Ultraviolet rays

(c)    X-rays

(d)    Sound waves

(32)           Diffraction fringes are

(a)    Equally spaced

(b)    Distance between them increases

(c)    Distance between then decreases

(d)    They are adjacent with no space in between

(33)           In monochromatic red light, a blue book will probably appear to be

(a)    Black

(b)    Purple

(c)    Green

(d)    No scientific reasoning available

(34)           A thing that emits its own light is

(a)    Luminous

(b)    Non-luminous

(c)    Incandescent

(d)    Bright

(35)           In double slit experiment, if one of the two slit is covered then

(a)    No interference fringes are observed

(b)    No diffraction fringes are observed

(c)    No fringes observed

(d)    Interference pattern not distributed

.     (36)      In Young’s double slit experiment, if d is the separation between the slits, destructive interference will occur if

(a) d sin q = m l :             (m = 0, 61, 6 2, .  . .)

                  (b) d sin q = (m + ½) l :     (m = 0, 61, 6 2, .  . .)

                  (c) 2d sin q = m /l :            (m = 0, 61, 6 2, .  . .)

            (d) 2 d sin q = m l :            (m = 0, 61, 6 2, .  . .)

(37)      In Young’s double slit experiment, if d is the separation between the slits, l is the wave- length of the light used and D is the distance of the screen from the slits, then the position of the mth bright fringe from the central position is given by

            (a)   y_m = m l D/d                           (b)  y_m =  (m + ½ ) l D/d  

            (c)   y_m = m l d/D             (d)  y_m = (m+ ½) l d/D

(38)      In Young’s double slit experiment, if d is the slits separation, l is the wave length of the light used and D is the distance of the screen from the slits, then the separation between two successive bright fringes or dark fringes is given by

             (a)                 (b)                      

             (c)                  (d)          

(39)       In monochromatic red light a blue book will appear

            (a)  red                   (b)  blue          

            (c)  purple              (d)  black

(40)      Which of the following properties is not found in both sound and light waves

                  (a) interference      (b)  diffraction          

                  (c)  polarisation      (d) dispersion