CBSE Questions for Class 12 Medical Physics Wave Optics Quiz 10 - MCQExams.com

Angular width of  central maximum of a diffraction pattern on a single does not depend upon :
  • Distance between slit and source
  • Wavelength of the light used
  • width of the slit
  • None of the above
In Young's double slit experiment $$10th$$ order maxima is obtained at the point of  observation in the interference pattern for $$\lambda = 7000 A^o$$. If the source is replaced by another one of wavelength $$5000\ A^o$$  then the order of maximum at the same point will be 
  • $$12\ th$$
  • $$14\ th$$
  • $$16\ th$$
  • $$18\ th$$
A parallel beam of monochromatic light of wavelength 5000 A is incident on a single narrow slit of width 0.001 mm. The light is focussed by a convex lens on a screen placed on focal plane. The first minimum will be formed formed for the angle of diffraction equal to 
  • $$20^{\circ}$$
  • $$15^{\circ}$$
  • $$30^{\circ}$$
  • $$50^{\circ}$$
Two coherent source must have the same :
  • amplitude
  • phase difference
  • frequency
  • both B and C
A monochromatic light is incident on a single slit of width $$24\times 10^{-5}\ cm$$. Calculate wavelength of light if angular position of $$1^{st}$$ secondary maxima is $$30^{o}$$.
  • $$8000\ A^{o}$$
  • $$12000\ A^{o}$$
  • $$6000\ A^{o}$$
  • $$16000\ A^{o}$$
A slit of size $$0.15cm$$ is placed at $$2.1m$$ from a screen. On illuminated it by a light of wavelength $$5 \times {10^{ - 5}}cm$$. The width of diffraction pattern will be:-
  • $$70nm$$
  • $$0.14nm$$
  • $$1.4nm$$
  • $$.014nm$$
A pale wavefront of wavelength $$\lambda$$ is incident in a single slit of width a
  • $$\dfrac {\lambda} {a}$$
  • $$\dfrac {2 \lambda} {a}$$
  • $$\dfrac {a} {\lambda}$$
  • $$\dfrac {a} {2 \lambda}$$
The first diffraction minimum due to single slit diffraction is $$\theta ,$$ for a light of wavelength $$5000 A.$$ If the width of the sit is $$1 \times {10^{ - 4}},$$ then the value of $$\theta $$ is
  • $${30^0}$$
  • $${45^0}$$
  • $${60^0}$$
  • $${15^0}$$
Two identical coherent sources placed on a diameter of a circle of radius R at separation $$x(<<R)$$ symmetrically about the centre of the circle. The sources emit identical wavelength $$\lambda $$ each. The number of points on the circle with maximum intensity is $$\left( {x = 5\lambda } \right)$$
  • 20
  • 22
  • 24
  • 26
In an interference pattern of two waves fringe width is $$\beta$$. If the frequency of source is doubled then fringe width will become:-
  • $$\dfrac{1}{2} \beta$$
  • $$ \beta$$
  • $$ 2\beta$$
  • $$\dfrac{3}{2} \beta$$
In $$Y.D.S.E$$. If the width of the slits are gradually decreased, then 
  • Bright fringe will become brighter and dark fringe become darker
  • Bright fringe become less bright and dark fringe becomes less dark
  • Bright fringe become brighter and dark fringe become lighter
  • Bright fringe become less bright and dark fringe becomes less darker
A light source of diameter $$2 cm$$ is placed $$20 cm$$ behind a circular opaque disc to diameter $$4 cm$$. Shadow is formed on a screen at a distance of $$80 cm$$, the ratio of the area of umbra and penumbra shadow region is equal to 
1247750_154796be95ba40dd9145370da2559406.png
  • $$0.58$$
  • $$0.22$$
  • $$0.18$$
  • $$0.11$$
Angle of incidence is equal to the angle of reflection.
  • Always
  • Sometimes
  • Under special condition
  • Never
The wave theory of light was given by
  • HUygen
  • Young
  • Maxwell
  • Olank
In YDSE, d = 2 mm, D = 2 m and$$\lambda $$  = 500 nm. If intensity of two slits are $$l _ { 0 }$$ and $$9 l _ { 0 }$$ then find intensity at  $$y = \frac { 1 } { 6 }$$
  • $$7 l _ { 0 }$$
  • $$10 l _ { 0 }$$
  • $$16 l _ { 0 }$$
  • $$4 l _ { 0 }$$
The displacement of the interfering sound waves are $${ y }_{ 1 }=4sincot$$ and $${ y }_{ 2 }=3sin\left( cot+\frac { \pi  }{ 2 }  \right) $$. What is the amplitude of the resultant wave
  • 5
  • 7
  • 1
  • 0
Light of wavelength $$\lambda $$ is incident on a slit of width d. The resulting Diffraction pattern is observed on screen at a distance D. the linear width of the principle maximum is then equal to width of the slit if D equals :
  • $$\dfrac {d} {\lambda} $$
  • $$\dfrac {2\lambda} {d}$$
  • $$\dfrac{{ d }^{ 2 }} {2\lambda} $$
  • $$\dfrac {2\lambda ^{ 2 }} {d}$$
Statement-1 : In standard YDSE set up with visible light, the position on screen where phase difference is zero appears bright.
and
Statement-2 : In YDSE set up magnitude of electromagnetic field at central bright fringe is not varying with time.
  • Statement-1 is true statement-2 is true and statement-2 is correct explanation for statement-1.
  • Statement-1 is true statement-2 is true and statement-2 is NOT the correct explanation for statement-1.
  • Statement-1 is true statement-2 is false.
  • Statement-1 is false statement-2 is true.
In a diffraction pattern due to a single slit of width $$a$$, the first minimum is observed at an angle $$30^{\circ}$$ when light of wavelength $$5000\overset {\circ}{A}$$ is incident on the slit. The first secondary maximum is observed at an angle of
  • $$\sin^{-1} \left (\dfrac {3}{4}\right )$$
  • $$\sin^{-1} \left (\dfrac {1}{4}\right )$$
  • $$\sin^{-1} \left (\dfrac {2}{3}\right )$$
  • $$\sin^{-1} \left (\dfrac {1}{2}\right )$$
If light waves emitted by an ordinary source, for what period of time, the phase remains constant :-
  • $$10 sec$$
  • $$1 sec$$
  • $$10^{-3}$$ sec
  • $$10^{-8}$$ sec
If $$I_0$$ is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity when the slit width is doubled
  • $$I_0$$
  • $$\dfrac{I_0}{2}$$
  • $$2I_0$$
  • $$4I_0$$
The main difference in the phenomenon of interference and diffraction is that:-
  • diffraction is due to interaction of light from the same wavefront whereas interference is the interaction of (light) waves from two isolated source.
  • diffraction is due to interaction of light from same wavefront whereas interference is the interaction of two waves derived from the same source.
  • diffraction is due to interaction of waves derived from the same source, whereas the interference is the bending of light from the same waveform
  • diffraction is caused by the reflected waves from a source whereas interference is caused due to waves from a source
Two point source separated by $$d=5\mu m$$ emit light of wavelength $$\lambda=2\mu m$$ in phase. A circular wire of radius $$20\ mu m$$ is placed around the source as shown in figure.
1281396_d07fc85051ff4bb6bc189c1ecea09d8e.png
  • Points $$A$$ and $$B$$ are dark and points $$C$$ and $$D$$ are bright.
  • Points $$A$$ and $$B$$ are bright and points $$C$$ and $$D$$ are dark.
  • Points $$A$$ and $$C$$ are dark and points $$B$$ and $$D$$ are bright.
  • Points $$A$$ and $$C$$ are bright and points $$B$$ and $$D$$ are dark.
A plane wave front of wave length $$6000A$$ is incident  upon a slit of $$0.2mm$$ width, which enables fraunhofer's diffraction pattern to be obtained on a screen $$2m$$ away. Width of the central maxima in mm will be 
  • $$10$$
  • $$12$$
  • $$8$$
  • $$2$$
Parallel beam is
  • produced by a source at infinity
  • produced by a source at finite distance
  • produced by a virtual source
  • None of these
What is the path difference of destructive interference :
  • $$n\lambda$$
  • $$n(\lambda +1)$$
  • $$\cfrac{(n+1)\lambda}{2}$$
  • $$\cfrac{(2n+1)\lambda}{2}$$
In diffraction using single slit, a slit of width a is illuminated by white light.  For red light $$\left( \lambda =6500\quad \overset { \circ  }{ A }  \right) $$, the first minima is obtained for $$\theta ={ 30 }^{ \circ  }$$. Then the value of a will be:
  • 3250 $$\overset { \circ }{ A } $$
  • $$6.5\times { 10 }^{ -4 }$$
  • 1.24 $$\mu m$$
  • $$2.6\times { 10 }^{ -4 }$$
Newton's corpuscular model of light.
  • successfully explain the rectilinear propagation of light, reflection of light and refraction of light
  • does not explain the phenomena of interference of light, diffraction of light and polarisation of light
  • is based upon particle theory of light
  • None of the above
In the case of parallel beam,
  • intensity gradually increases
  • intensity gradually decreases
  • intensity remains constant
  • None of these
According to Huygen's theory of light
  • light is stream of photon
  • light is wave
  • light behaves as particle
  • None of the above
What will be the angular width of central maxima in Fraunhoffer diffraction when light of wavelength $$6000\ \mathring {A}$$ is used and slit width is $$12\ \times 10^{-5}\ cm$$.
  • $$2\ rad$$
  • $$3\ rad$$
  • $$1\ rad$$
  • $$8\ rad$$
The bending of beam of light around corners of obstacles is called
  • Reflecton
  • Diffraction
  • Refraction
  • Interference
In a biprism experiment, the distance of 20 th bright bandfrom the center of the interference pattern is 8$$\mathrm { mm }$$ . The distance of 30th bright band from the center is
  • $$11.8\mathrm { mm }$$
  • 12$$\mathrm { mm }$$
  • 14$$\mathrm { mm }$$
  • 16$$\mathrm { mm }$$
If the ratio of maximum and maximum Intensities tn an interference pattern is 36: 1 then the ratio of amplitudes of two Interfering waves Will be
  • 5 :7
  • 7 :4
  • 4 :7
  • 7 :5
In Y.D.S.E. how many maxima can be obtained on the screen if wave length of light used is $$200 mm$$ & $$d = 700 mm$$ :- 
  • $$12$$
  • $$7$$
  • $$18$$
  • $$14$$
What is the effect on the interference fringes in Young's double slit experiment if the source slit is moved closer to the double slit plane?
  • The fringe width increases
  • The fringe width decreases
  • The fringes become more distinct
  • The fringes become less distinct
If the frequency of the source is doubled in Young's double slit experiment, then fringe width $$( \beta )$$ will be-
  • unchanged
  • $$\beta / 2$$
  • $$2 \beta$$
  • $$3 \beta$$
In YDSE if white is used then.
  • except center, there will be spectrum
  • except center no spectrum any where
  • spectrum every where
  • spectrum at center only
In a double-slit experiment, green light $$(5303\overset{o}{A})$$ falls on a double slit having a separation of $$19.44\ \mu m$$ and a width of $$4.05\ \mu m$$. The number of bright fringes between the first and the second diffraction minima is?
  • $$09$$
  • $$10$$
  • $$04$$
  • $$05$$
When an unpolarized light of intensity $$I_0$$ is incident on a polarizing sheet the intensity of the light which does not get transmitted is?
  • Zero
  • $${I}_{0}$$
  • $$\cfrac{1}{2}{I}_{0}$$
  • None
Huygen's theory of secondary waves can be used of find-
  • Velocity of light
  • The wavelength of light
  • Wave front geometrically
  • Magnifying power of microscope
The wavefront of a light beam is given by the equation $$x + 2 y + 3 z = c$$ , (where c is arbitrary constant) then what is the angle made by the direction of light with the y-axis?
  • $$\cos ^ { - 2 } \frac { 2 } { \sqrt { 14 } }$$
  • $$\cos ^ { - 1 } \frac { 2 } { \sqrt { 14 } }$$
  • $$\cos ^ { - 3 } \frac { 2 } { \sqrt { 14 } }$$
  • $$\cos ^ { - 4 } \frac { 2 } { \sqrt { 14 } }$$
Consider Fraunhoffer diffraction pattern obtained with a single slit illuminate incidance. At the angular position of the first diffraction minimum in the phase( radian) between the wavelets from the opposite edges of the slit is  
  • $$\dfrac {\pi} 4$$
  • $$\dfrac {\pi} 2$$
  • $$ {\pi}$$
  • $$2\pi$$
What wavelength of light would you be able to resolve at the fastest distance based on diffraction?
  • Red $$(\lambda=650nm)$$
  • Green $$(\lambda=550nm)$$
  • Blue $$(\lambda=450nm)$$
  • All the wavelengths will be resolved equally
Fraunhoffer lines are obtained in
  • Solar spectrum
  • The spectrum obtained from neon lamp
  • Spectrum from a discharge tube
  • None of the above
The figure shows a double slit experiment where $$  P  $$ and $$  Q $$ are the slits. The path lengths $$  P X  $$ and $$  Q X  $$ are $$  n \lambda  $$ and $$ (n+2) \lambda  $$ respectively, where $$  n  $$ is a whole number and $$  \lambda  $$ is the wavelength. Taking the central fringe as zero, what is formed at $$  X $$
1378273_676d3d1faedd47759fd9fb6ace92480c.png
  • First bright
  • First dark
  • Second bright
  • Second dark
Which of following nature of light waves is supported by the phenomenon of interference:
  • longitudinal
  • transverse
  • both transverse and longitudinal
  • none of the above
Light of wavelength 6000 is incident bria single slit. The first minimum of the diffraction pattern is obtained at 4 mm from the centre. The screen is at a distance of 2 m from the slit.
  • 0.15 mm
  • 0.1 mm
  • 0.3 mm
  • 0.2 mm
We could observe path of light due to ........... of light from tiny particle of solution of transparent medium.
  • Scatterign
  • Dispersion
  • Refraction
  • Reflaction
Electrons accelerated by potential $$V$$ are diffracted from a crystal. If $$d = 1\overset {\circ}{A}$$ and $$i = 30^{\circ}, V$$ should be about $$(h = 6.6\times 10^{-34} J-s, m_{e} = 9.1\times 10^{-31} kg, e = 1.6\times 10^{-19}C)$$.
  • $$2000\ V$$
  • $$50\ V$$
  • $$500\ V$$
  • $$1000\ V$$
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