CBSE Questions for Class 12 Medical Physics Wave Optics Quiz 4 - MCQExams.com

Ramesh was playing in the garden on a sunny day. He observed almost elliptical splashes of sunlight on the ground as he walked under a tree. What did he observe ?
  • Shadow of the leaves
  • Shadow of the fruits on the tree
  • Pinhole-camera images of sun formed by spaces between leaves in canopy.
  • None of these
Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil of diameter 3 mm. Approximately what is the maximum distance up to which these dots can be resolved by the eye.
  • 5 m
  • 6 m
  • 1 m
  • 4 m
The first diffraction minimum due to a single slit Fraunhoffer diffraction is at the angle of diffraction $$30 ^ { \circ }$$ for a light of wave length 5000 $$A ^ { 0 }$$ .The width of the slit is 
  • $$1.0 \times 10 ^ { - 4 } \mathrm { cm }$$
  • $$2.164 \times 10 ^ { - 4 } \mathrm { cm }$$
  • $$1.082 \times 10 ^ { - 3 } \mathrm { cm }$$
  • $$0.546 \mathrm { cm }$$
Two light sources are coherent when:
  • Only their frequency are equal
  • their wavelength are equal
  • Their amplitudes are equal
  • Time frequency are equal and their phase
The diffraction effect can be observed in
  • only sound waves
  • only light waves
  • only ultrasonic waves
  • sound as well as light waves
A double slit is illuminated by light of wave length 6000$$A ^ { 0 }$$.The slits are 0.1 cm apart and the screen is placed 1 m away. Then the angular position of 10th maxima is
  • $$6 \times 10 ^ { - 3 } r a d$$
  • 6 rad
  • $$0.006 ^ { \circ }$$
  • $$6 ^ { 0 }$$
The angular spread of central maximum, in the diffraction pattern, does not depend on ______
  • the distance between the slit and sources
  • width of slit
  • wavelength of light
  • frequency of light
Which of the following is correct for light diverging from a point source ?
  • The intensity decreases in proportion for the distance squared.
  • The wavefront is parabolic.
  • The intensity at the wavelength does not depend on the distance.
  • None of these.
To observe diffraction, the size of the obstacle
  • Should be $$\lambda /2$$ where is the wavelength
  • Should be of the order of wavelength.
  • Has no relation to wavelength.
  • should be much larger than the wavelength.
Which one is not produced by sound waves in air?
  • Polarisation
  • Diffraction
  • Refraction
  • Reflection
Coherent sources are characterized by the same:
  • phase and phase velocity
  • wavelength, amplitude and phase velocity
  • wavelength, amplitude and frequency
  • wavelength and phase
The wavelength of light visible to eye is of the order of 
  • $$10^{-2}\ m$$
  • $$10^{-10}\ m$$
  • $$1\ m$$
  • $$6\times 10^{-7}\ m$$
Which of the following phenomenon can explain quantum nature of light
  • Photoelectric effect
  • Interference
  • Diffrection
  • Polarisation
If $$L$$ is the coherent length and $$c$$ the velocity of light, the coherent time is
  • $$cL$$
  • $$\dfrac{L}{c}$$
  • $$\dfrac{c}{L}$$
  • $$\dfrac{1}{Lc}$$
A star moves away from earth at speed $$0.8\ c$$ while emitting light of frequency $$6\times 10^{14}Hz$$. What frequency will be observed on the earth (in units of $$10\ Hz$$)( $$c=$$ speed of light)
  • $$0.24$$
  • $$1.2$$
  • $$30$$
  • $$3.3$$
The wave front due to a source situated at infinity is :
  • spherical
  • cylindrical
  • planar
  • none of these
In Young's double slit experiment, first slit has width four times the width of the second slit. The ratio of the maximum intensity to the minimum intensity in the interference fringe system is:
  • $$2:1$$
  • $$4:1$$
  • $$9:1$$
  • $$8:1$$
In Young's double slit experiment, the two equally bright slits are coherent, but of phase difference $$\dfrac{\pi }{3}$$. If maximum intensity on the screen is $$I_{o}$$, the intensity at the point on the screen equidistant from the slits is:
  • $$I_{o}$$
  • $$\dfrac{I_{o}}{2}$$
  • $$\dfrac{I_{o}}{4}$$
  • $$\dfrac{3I_{o}}{4}$$
Light of wavelength $$6000\ A$$$$^{\circ}$$ from a distant source falls on a slit $$0.5\ mm$$ wide. The distance between two dark bands on each side of the central bright band of the diffraction pattern observed on a screen placed at a distance $$2\ m$$ from the slit is:
  • $$1.2\ nm$$
  • $$2.4\ nm$$
  • $$3.6\ nm$$
  • $$4.8\ mm$$
Anti-nodal curves represent the points joining:
  • destructive interference
  • constructive interference
  • equal phase curves
  • equal pressure curves
  • zero pressure curves
In a Young's double slit experiment using red and blue lights of wavelengths $$600\ mm$$ and $$480\ nm$$ respectively, the value of $$n$$ for which the $$n^{th}$$ red fringe coincides with $$(n + 1)^{th}$$ blue fringe is
  • $$5$$
  • $$4$$
  • $$3$$
  • $$2$$
If one of the two slits of a Young's double slit experiment is painted over so that it transmits half the light intensity of the other, then:
  • the fringe system would disappear
  • the bright fringes would be brighter & dark fringes would be darker
  • the dark fringes would be brighter and bright fringes would be darker
  • bright as well as dark fringes would be darker
The wave fronts of light wave traveling in vacuum are given by $$x+y+z=c$$ . The angle made by the light ray with the x-axis is:
  • 0$$^{\circ}$$
  • 45$$^{\circ}$$
  • 90$$^{\circ}$$
  • $$cos^{-1}\dfrac{1}{\sqrt{3}}$$
If $$I_{o}$$ is the intensity of the principle maximum in the single slit diffraction pattern then, with doubling the slit width, the intensity becomes:
  • $$I_{o}$$
  • $$I_{o}$$ / 2
  • $$\frac{1}{2}$$$$I_{o}$$
  • 4$$I_{o}$$
The two coherent sources of equal intensity produce maximum intensity of $$100$$ units at a point. If the intensity of one of the sources is reduced by $$36\%$$ by reducing its width, then the intensity of light at the same point will be :
  • 90
  • 89
  • 67
  • 81
Two waves $$y_{1}=A_{1}sin (\omega t-\beta _{1})$$ and $$y_{2}=A_{2}sin (\omega t-\beta _{2})$$ superimpose to form a resultant wave whose amplitude is :
  • $$\sqrt{A_{1}^{2}+A^{2}_{2}+2A_{1}A_{2}cos(\beta _{1}-\beta _{2})}$$
  • $$\sqrt{A_{1}^{2}+A^{2}_{2}+2A_{1}A_{2}sin(\beta _{1}-\beta _{2})}$$
  • $$A_{1}+A_{2}$$
  • $$|A_{1}+ A_{2}|$$
A beam of light of wavelength 600 nm from a distant source falls on a single slit 1.0 mm wide and the resulting diffraction pattern is observed on a screen 2m away. The distance between the first dark fringes on either side of the central bright fringe is:
  • 1.2 cm
  • 1.2 mm
  • 2.4 cm
  • 2.4 mm
In Young's double slit experiment the intensity of the maxima is $$I$$. If the width of each slit is doubled, the intensity of the maxima will be:
  • $$I/2$$
  • $$2I$$
  • $$4I$$
  • $$I$$
A screen is placed 2m away from a single narrow slit. The slit width if the first minimum lies 5 mm on either side of the central maximum is:
(wave length $$=$$ 5000A$$^{\circ} $$)
  • $$0.01cm$$
  • $$0.02cm$$
  • $$0.03cm$$
  • $$0.04cm$$
The diameter of the objective of a telescope is $$a$$, its magnifying power is $$m$$ and wavelength of light $$\lambda $$ . The resolving power of the telescope is :
  • $$\dfrac{(1.22\lambda )}{a}$$
  • $$\dfrac{1.22a}{\lambda} $$
  • $$\lambda (1.22a)$$
  • $$\dfrac {a} {1.22\lambda} $$
Yellow light is used in a single slit diffraction experiment with a slit of width $$0.6 mm$$. If yellow light is replaced by $$X-$$ rays, then the observed pattern will reveal :
  • more number of fringes
  • less number of fringes
  • no diffraction pattern
  • that the central maximum is narrower
A person wants to see two pillars from a distance of 11 km, separately. The distance between the pillars must be approximately
  • 3.2m
  • 1m
  • 0.25 m
  • 0.5 m
ASSERTION: Resolving power of telescope is more if the diameter of the objective lens is more.
REASON:Objective lens of large diameter collects more light.
  • both A and R are correct and R is correct explanation of A
  • A and R both are correct but R is not correct explanation of A
  • A is true but R is false
  • both A and R is false
A parallel beam of monochromatic light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of the slit is :
  • zero
  • $$\dfrac{\pi }{2}$$
  • $$\pi $$
  • $$2\pi $$
Match the following : 
PART-A PART-B
a) Polarisation e) All types of waves
b) interference   f) longitudinal waves
c) diffraction  g) transverse waves
d) reflection h) only with transverse waves
 i) stationary waves produced in stretched strings
  • a$$\rightarrow$$ g ; b$$\rightarrow$$ e, f , g,i ; c$$\rightarrow$$ e, f , g ; d $$\rightarrow$$ e, f , g
  • a$$\rightarrow$$h, g; b$$\rightarrow$$ f , g ; c$$\rightarrow$$ g ; d $$\rightarrow$$ h
  • a$$\rightarrow$$ e, f , g; b$$\rightarrow$$ g ; c$$\rightarrow$$ e, f , g ; d $$\rightarrow$$ g
  • a$$\rightarrow$$ e; b$$\rightarrow$$ h,i ; c$$\rightarrow$$ g, h ; d $$\rightarrow$$ e
The limit of resolution of microscope, if the numerical aperture of microscope is 0.12, and the wavelength of light used is 600 nm, is 
  • 0.3$$\mu $$m
  • 1.2 $$\mu $$m
  • 2.5$$\mu $$m
  • 3$$\mu $$m
Light waves travel in vaccum along the y-axis. Then the wave front is:
  • $$y=$$ constant
  • $$x=$$ constant
  • $$z=$$ constant
  • $$x+y+z =$$ constant
If accelerating potential increases from $$20\ KV$$ to $$80\ KV$$ in an electron microscope, its resolving power $$R$$ would change to
  • $$\dfrac{R}{4}$$
  • $$4R$$
  • $$2R$$
  • $$\dfrac{R}{2}$$
The magnitude of magnifying power of an astronomical telescope is 5, the focal power of its eyepiece is 10 diopters. The focal power of its objective (in diopters) is
  • $$1$$
  • $$2$$
  • $$3$$
  • $$4$$
A telescope has an objective lens of 10 cm diameter and is situated at a distance of $$1km$$ for two objects. The minimum distance between these two objects, which can be resolved by the telesope, when the mean wavelength of light is 5000Å is of the order of
  • 5 cm
  • 0.5 mm
  • 5 m
  • 5 mm
To demonstrate the phenomenon of interference of sound, we need:
  • two sources, which emit sound of exactly the same frequency
  • two sources, which emit sound of exactly the same frequency and have a definite phase relationship
  • two sources, which emit sound of exactly the same frequency and have a varying phase relationship
  • two sources, which emit sound of exactly the same wavelength

Two coherent sources of intensity ratio $$\beta$$ interfere. Then the value of $$\displaystyle \left( {\frac{{{I_{\max }} - {I_{\min }}}}{{{I_{\max }} + {I_{\min }}}}} \right)$$ is:
  • $$\dfrac{{1 + \beta }}{{\sqrt \beta }}$$
  • $$\sqrt {\left( {\dfrac{{1 + \beta }}{\beta }} \right)} $$
  • $$\dfrac{{1 + \beta }}{{2\sqrt \beta }}$$
  • $$\dfrac{{2\sqrt \beta }}{{1 + \beta }}$$
The resolution limit of the eye is $$1'$$. At a distance $$x\ km$$ from the eye, two persons stand with a lateral separation of 3 meter. For the two persons to be just resolved by the naked eye, $$x$$ should be:
  • $$10 km$$
  • $$15 km$$
  • $$20 km$$
  • $$30 km$$
An astronomical telescope has a large aperture to
  • reduce spherical aberration
  • have high resolution
  • increase span of observation
  • have low dispersion
Two point white dots are $$1\ mm$$ apart on a black paper. They are viewed by eye of pupil diameter $$3\ mm$$. Approximately, what is the maximum distance at which these dots can be resolved by the eye? (Take wavelength of light $$= 500\ nm$$)
  • 6 m
  • 3 m
  • 5 m
  • 1 m
In double slit experiment, for light of which colour, the fringe width will be minimum?
  • Violet
  • Red
  • Green
  • Yellow
A telescope has an objective lens of 10 cm diameter and is situated at a distance of one kilometer from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is $$5000 \dot{A}$$, is of the order of :
  • 5 m
  • 5 mm
  • 5 cm
  • 0.5 m
Identify the correct statement from the following :
  • Wave nature of light was proposed by Huygens.
  • The direction of light ray and its wave front are opposite.
  • Huygen's wave theory could not explain phenomenon of reflection.
  • A monochromatic ray of light after passing through the prism should create a spectrum of seven colours.
The wave front is a surface in which:
  • All points are in the same phase
  • There is a pair of points in opposite phase
  • There is a pair of points with phase difference $$(\cfrac {\pi}{2})$$
  • There is no relation between the phase
The phenomenon of interference is shown by
  • Longitudinal mechanical waves only
  • Transverse mechanical waves only
  • Non-mechanical transverse waves only
  • All the above types of waves
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