CBSE Questions for Class 12 Medical Physics Wave Optics Quiz 13 - MCQExams.com

In the interference of waves from two sources of intensities $$I_{0}$$ and $$4I_{0}$$. The intensity at a point where the phase difference is $$\pi$$ is 
  • $$I_{0}$$
  • $$2I_{0}$$
  • $$3I_{0}$$
  • $$4I_{0}$$
In a Young's double slit experiment, the distance between the two identical slits is 6.1 times larger than the slit width. Then the number of intensity maxima observed within the central maximum of the single slit diffraction pattern is :
  • 3
  • 6
  • 12
  • 24
True & False Statement Type
$$S_1$$ : In an elastic collision initial and final K.E. of system will be same.
$$S_2$$ : In a pure L-C Circuit average energy stored in capacitor is zero.
$$S_3$$ : In YDSE coherent sources are formed by division of wave front method.
$$S_4$$ : If a physical Quantity is quantized then it must be integral multiple of its lowest value.
  • FFTF
  • TTFT
  • FTFT
  • TFTT
A single slit of width $$a$$ is illuminated by violet light of wave length $$400\ nm$$ and width of the diffraction pattern is measured as $$y$$. Half of the slit is covered and illuminated with $$600\  nm$$. The width of the diffraction pattern will be
  • $$\dfrac{y}{3}$$
  • pattern vanishes and width is zero
  • $$3y$$
  • none of these
Find the nature and order of the interference at O 

76636.jpg
  • $$20^{th} $$ minima
  • $$20^{th} $$ maxima
  • $$10^{th} $$ maxima
  • $$10^{th} $$minima
An astronomical telescope, consists of two thin lenses set $$36 cm$$ a part and has a magnifying power $$8$$. Calculate the focal length of the lenses.
  • $$32 cm$$
  • $$18 cm$$
  • $$25 cm$$
  • $$36 cm$$
In an experiment of single slit diffraction pattern, first minimum for red light coincides with first maximum of some other wavelength. If wavelength of red light is $$6000 A^o$$, then wavelength of first maximum will be
  • $$3000 A^o$$
  • $$4000 A^o$$
  • $$5000 A^o$$
  • $$6000 A^o$$
Light of wavelength 589.3 nm is incident normally on a slit of width 0.1 mm. The angular width of the central diffraction maximum at a distance of 1m from the slit is 
  • $$0.68^\circ$$
  • $$0.34^\circ$$
  • $$2.05^\circ$$
  • None of these
Find the nature and order of the interference at the point P :

76636.jpg
  • $$70^{th}$$ maxima
  • $$80^{th}$$ minima
  • $$60^{th}$$ maxima
  • $$70^{th}$$ minima
$${M}_{1}$$ and $${M}_{2}$$ are plane mirrors and kept parallel to each other. At point O, there will be a maxima for wavelength $$\lambda$$. Light from a monochromatic source $$S$$ of wavelength $$\lambda$$ is not reaching directly on the screen. Then, $$\lambda$$ is:

164547_511e2de9f0614c5e8ec3e4593b242135.png
  • $$\cfrac { { 3d }^{ 2 } }{ D } $$
  • $$\cfrac { { 3d }^{ 2 } }{ 2D } $$
  • $$\cfrac { { d }^{ 2 } }{ D } $$
  • $$\cfrac { { 2d }^{ 2 } }{ D } $$
The intensity of light from a source is 500 / $$\pi W/m^{2}$$. Find the amplitude of electric field in this wave -
  • $$\sqrt{3}\times 10^{2}N/C$$
  • $$2\sqrt{3}\times 10^{2}N/C$$
  • $$\frac{\sqrt{3}}{2}\times 10^{2}N/C$$
  • $$2\sqrt{3}\times 10^{1}N/C$$
Two identical coherent sources are placed on a diameter of a circle of radius $$R$$ at separation $$x(<<R)$$ symmetrical about the center of the circle. The sources emit identical wavelength $$\lambda$$ each. The number of points on the circle of maximum intensity is $$(x=5\lambda$$):
  • $$20$$
  • $$22$$
  • $$24$$
  • $$26$$
Light of wavelength $$500nm$$ goes through a pinhole of $$0.2mm$$ and falls on a wall at a distance of $$2m$$. What is the radius of the central bright spot formed on the wall?
  • $$2.37 cm$$
  • $$1.37 cm$$
  • $$3.37 cm$$
  • $$7.37 cm$$
Two points sources separated by $$2.0m$$ are radiating in phase with $$\lambda=0.50m$$. A detector moves in a circular path around the two sources in a plane containing them. How many maxima are detected?

164444_d86779a0629649e4b78dd73be85db534.png
  • $$16$$
  • $$20$$
  • $$24$$
  • $$32$$

164922.PNG
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
A radio transmitting station operating at a frequency of $$120$$MHz has two identical antennas that radiate in phase. Antenna $$B$$ is $$9m$$ to the right of antenna $$A$$. Consider point $$P$$ at a horizontal distance $$x$$ to the right of antenna $$A$$ as shown figure. The value of $$x$$ and order for which the constructive interference will occur at point $$P$$ are

164901_5094caad5f504deeaf7c3dc2374bb33d.png
  • $$x=14.95m,n=1$$
  • $$x=5.6m,n=2$$
  • $$x=1.65m,n=3$$
  • $$x=0,n=3.6$$
If a maxima is formed at a detector, then the magnitude of wavelength $$\lambda$$ of the wave produced is given by

165036_e3982356ab7c4744afa1bf92945471b0.png
  • $$\pi R$$
  • $$\cfrac{\pi R}{2}$$
  • $$\cfrac{\pi R}{4}$$
  • all of these
A parallel beam of light $$(\lambda=500nm)$$ is incident at an angle $$\alpha={30}^{o}$$ with the normal to the slit plane in Young's double-slit experiment. Assume that the intensity due to each slit at any point on the scree is $${I}_{0}$$. Point $$O$$ is equidistant from  $${S}_{1}$$ and $${S}_{2}$$. The distance between slits is $$1mm$$. Then

164857_e47473c44b664516b3a81d62f8811d17.png
  • the intensity at $$O$$ is $${I}_{0}$$
  • the intensity at $$O$$ is zero
  • the intensity at a point on the screen $$1m$$ below $$O$$ is $${I}_{0}$$
  • the intensity at a point on the screen $$1m$$ below $$O$$ is zero
In a Young's double slit experiment set up, source $$S$$ of wavelength $$500 nm$$ illuminates two slits $$S_{1}$$ and $$S_{2}$$ which act as two coherent sources. The source $$S$$ oscillates about its own position according to the equation $$y = 0.5 \sin \pi t$$ where $$y$$ is in mm and $$t$$ in seconds. The minimum value of time $$t$$ for which the intensity at point $$P$$ on the screen exactly infront of the upper slit becomes minimum is :
164698.PNG
  • $$1 s$$
  • $$2 s$$
  • $$3 s$$
  • $$1.5 s$$
If a minima is formed at the detector, then the magnitude of wavelength $$\lambda$$ of the wave produced is given by

165037_5f112f51561d40c9889e8a2d5e121439.png
  • $$2\pi R$$
  • $$\cfrac{3}{2}\pi R$$
  • $$\cfrac{5}{2}\pi R$$
  • none of these
If $$z=\cfrac{\lambda D}{4d}$$

165212.PNG
  • $${ \left[ 3-2\sqrt { 2 } \right] }^{ 2 }$$
  • $${ \left[ 3+\sqrt { 2 } \right] }^{ 2 }$$
  • $${ \left[ 3-\sqrt { 2 } \right] }^{ 2 }$$
  • $${ \left[ 3+2\sqrt { 2 } \right] }^{ 2 }$$
Consider the optical system shown in the figure that follows. The point source of light $$S$$ is having wavelength equal to $$\lambda$$. The light is reaching screen only after reflection. For point $$P$$ to be $$2^{nd}$$ maxima, the value of $$\lambda$$ would be $$(D > > d$$ and $$d > > \lambda)$$ :
164572_7721dcf92be84ebfa270b6e54320e2ee.png
  • $$\dfrac {12d^{2}}{D}$$
  • $$\dfrac {6d^{2}}{D}$$
  • $$\dfrac {3d^{2}}{D}$$
  • $$\dfrac {24d^{2}}{D}$$
The YDSE apparatus is as shown in the figure. The condition for point $$P$$ to be a dark fringe is ($$l=$$wavelength of light waves)

164569.png
  • $$\left( { l }_{ 1 }-{ l }_{ 3 } \right) +\left( { l }_{ 2 }-{ l }_{ 4 } \right) =n\lambda $$
  • $$\left( { l }_{ 1 }-{ l }_{ 2 } \right) +\left( { l }_{ 3 }-{ l }_{ 4 } \right) =\cfrac { \left( 2n+1 \right) \lambda }{ 2 } $$
  • $$\left( { l }_{ 1 }+{ l }_{ 3 } \right) +\left( { l }_{ 2 }+{ l }_{ 4 } \right) =\cfrac { \left( 2n-1 \right) \lambda }{ 2 } $$
  • $$\left( { l }_{ 1 }-{ l }_{ 2 } \right) +\left( { l }_{ 4 }-{ l }_{ 3 } \right) =\cfrac { \left( 2n-1 \right) \lambda }{ 2 } $$

164927.PNG
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect Reason is correct
A long horizontal slit is place $$1\ mm$$ above a horizontal plane mirror. The interference between the light coming directly from the slit and that after reflection is seen on a screen $$1\ m$$ away from the slit. If the mirror reflects only $$64\%$$ of the light falling on it, the ratio of the maximum to the minimum intensity in the interference pattern observed on the screen is :
  • $$8 : 1$$
  • $$3 : 1$$
  • $$81 : 1$$
  • $$9 : 1$$
If $$z=\cfrac{\lambda D}{d}$$

165212.PNG
  • $$4$$
  • $$2$$
  • $$\infty$$
  • $$1$$
At $$t=0$$, fringe width is $${\beta}_{1}$$, and at $$t=2s$$, fringe width of figure is $${\beta}_{2}$$. Then

165043.PNG
  • $${\beta}_{1}> {\beta}_{2}$$
  • $${\beta}_{2}> {\beta}_{1}$$
  • $${\beta}_{1}= {\beta}_{2}$$
  • data is insufficient
At $$t=2s$$, the position of central maxima is

165043.PNG
  • $$2mm$$ above $$C$$
  • $$2mm$$ below $$C$$
  • $$4mm$$ above $$C$$
  • $$4mm$$ below $$C$$
In the arrangement shown in figure, $$D>>d$$. For what minimum value of $$d$$ is there a dark band at point $$O$$ on the screen?

165205_75c56220f2a6486fb7beea3fde2d748a.png
  • $$\sqrt{\cfrac{D\lambda}{4}}$$
  • $$\sqrt{\cfrac{3D\lambda}{4}}$$
  • $$\sqrt{\cfrac{D\lambda}{8}}$$
  • $$\sqrt{\cfrac{2D\lambda}{3}}$$
A liquid of refractive index $$\mu$$ is filled between the screen and slits.
  • $$\cfrac { 2\pi }{ \lambda } \left[ \left[ \sqrt { { d }^{ 2 }+{ x }_{ 0 }^{ 2 } } +{ x }_{ 0 } \right] +\cfrac { \mu { d }^{ 2 } }{ 2D } \right] $$
  • $$\cfrac { 2\pi }{ \lambda } \left[ \left[ \sqrt { { d }^{ 2 }+{ x }_{ 0 }^{ 2 } } -{ x }_{ 0 } \right] +\cfrac { \mu { d }^{ 2 } }{ 2D } \right] $$
  • $$\cfrac { 2\pi }{ \lambda } \left[ \left[ \sqrt { { d }^{ 2 }-{ x }_{ 0 }^{ 2 } } +{ x }_{ 0 } \right] +\cfrac { \mu { d }^{ 2 } }{ 2D } \right] $$
  • $$\cfrac { 2\pi }{ \lambda } \left[ \left[ \sqrt { { d }^{ 2 }-{ x }_{ 0 }^{ 2 } } -{ x }_{ 0 } \right] +\cfrac { \mu { d }^{ 2 } }{ 2D } \right] $$
If $$z=\cfrac{\lambda D}{2d}$$

165212.PNG
  • $$1$$
  • $$1/2$$
  • $$3/2$$
  • $$2$$
If the incident beam makes an angle of $${30}^{o}$$ with the x-axis (as in the dotted arrow shown in the figure), find the y-coordinates of the first minima on either side of the central maximum..

165096_21e2431889d749bcbb1a0c85ef58e196.png
  • $$\cfrac { 3 }{ \sqrt { 7 } } $$ and $$\cfrac { 1 }{ \sqrt { 15 } }m $$
  • $$\cfrac { 3 }{ \sqrt { 7 } } $$ and $$\cfrac { 2 }{ \sqrt { 15 } }m $$
  • $$\cfrac { 3 }{2 \sqrt { 7 } } $$ and $$\cfrac { 1 }{ \sqrt { 15 } }m $$
  • $$\cfrac { 6 }{ \sqrt { 7 } } $$ and $$\cfrac { 3 }{ \sqrt { 15 } }m $$
In the arrangement shown in figure, $$D>>d$$. Find the fringe width.

165209_1e999654d5014b8ab0d5a6f356401f7a.png
  • $$d$$
  • $$2d$$
  • $$4d$$
  • $$3d$$
In the arrangement shown in figure, $$D>>d$$. Find the distance $$x$$ at which the next bright fringe is formed.

165207_0c45417b2e224d39b5b51e8dacee8f5c.png
  • $$\cfrac{3\lambda}{2}$$
  • $$\cfrac{\lambda}{4}$$
  • $$\cfrac{\lambda}{2}$$
  • $$\cfrac{5\lambda}{2}$$
Determine the width of the region where the fringes will be visible

165225.PNG
  • $$4cm$$
  • $$6cm$$
  • $$2cm$$
  • $$3cm$$
Find the fringe width of the fringe pattern.

165225.PNG
  • $$0.05cm$$
  • $$0.25cm$$
  • $$0.01cm$$
  • $$0.1cm$$
The fractional change in intensity of the central maximum as function of time is

165488.PNG
  • $$\cfrac { A\sin { \omega t } }{ L } $$
  • $$\cfrac { 2A\sin { \omega t } }{ L } $$
  • $$\cfrac { 3A\sin { \omega t } }{ L } $$
  • $$\cfrac { 4A\sin { \omega t } }{ L } $$
When the source comes toward the point $$Q$$,

165488.PNG
  • the bright fringes will be less bright
  • the dark fringes will no longer remain dark
  • the fringe width will increase
  • none of these
Light of wavelength $$6328 \overset{o}{A}$$ is incident normally on a slit having a width of $$0.2 mm$$. The angular width of the central maximum measured from minimum to minimum of diffraction pattern on a screen $$9.0$$ meters away will be about
  • $$0.36 degree$$
  • $$0.18 degree$$
  • $$0.72 degree$$
  • $$0.09 degree$$
Calculate the number of fringes.

165225.PNG
  • $$10$$
  • $$20$$
  • $$30$$
  • $$40$$
The position of the direct image obtained at O$$_3$$, when a monochromatic beam of light is passed through a plane transmission grating at normal incidence as shown in Fig. The diffracted images A, B and c correspond to the first, second and third order diffraction. when the source is replaced by another source of shorter wave-length
210237.png
  • all the four will shift in the direction C to O
  • all the four will shift in the direction O to C
  • the images C, B and A will shift towards O
  • the images C,B and A will shift away from O
A point source is emitting light of wavelength 6000 $$\overset{o}{A}$$ is placed at a very small height h above a flat reflecting surface $$MN$$ as shown in the figure. The intensity of the reflected light is $$36$$% of the incident intensity. Inference fringes are observed on a screen placed parallel to the reflecting surface at a very large distance $$D$$ from it. If the intensity at $$p$$ be maximum, then the minimum distance through which the reflecting surface $$MN$$ should be displaced so that at $$P$$ again becomes maximum?
212140_40888d4dd11444c099999cf9908704ea.png
  • 3 $$\times$$ 10$$^{-7}$$ m
  • 6 $$\times$$ 10$$^{-7}$$ m
  • 1.5 $$\times$$ 10$$^{-7}$$ m
  • 12 $$\times$$ 10$$^{-7}$$ m
Two identical coherent sources are placed on a diameter of a circle of radius R at a separation d (d << R, d >> $$\lambda$$) symmetrically about the centre of the circle. The sources emit identical wavelength $$\lambda$$. The number of the points on the circle with maximum intensity is
  • $$\displaystyle \frac{2d}{\lambda }+1$$
  • $$\displaystyle \frac{4d}{\lambda }$$
  • $$\displaystyle \frac{4d}{\lambda }-2$$
  • $$\displaystyle \frac{4d}{\lambda }+2$$
In Young's double slit experiment if the slit widths are in the ratio $$1:9$$. The ratio of the intensity at minima to that at maxima will be :
  • $$1$$
  • $$\dfrac{1}{9}$$
  • $$\dfrac{1}{4}$$
  • $$\dfrac{1}{3}$$
Ratio of maximum to minimum intensities at $$P$$ is
212141_ecc6bd0877ed4cf68a12b4035577fc20.png
  • $$2 : 1$$
  • $$4 :1$$
  • $$8 : 1$$
  • $$16 : 1$$
An interference is observed due to two coherent sources 'A'  & 'B' separated by a distance of 4$$\lambda$$ along the y-axis where $$\lambda$$ is the wavelength of the source. A detector D  is moved on the positive x-axis. The number of points on the x-axis excluding the points, x =0 & x =$$\infty$$  at which maximum will be observed is
293712_fb399e22793948f793d957b7d496683c.png
  • three
  • four
  • two
  • infinite
The shape of the interference fringes, on the screen is 
212139_64d008c3bb814bf88adbd5df15fd0fbc.png
  • circle
  • ellipse
  • parabola
  • straight line
Light is incident at an angle $$\displaystyle \phi $$ with the normal to a plane containing two slits of separation d Select the expression that correctly describe the positions of the interference maxima in terms of the incoming angle $$\displaystyle \theta $$ and outgoing $$\displaystyle \phi $$
330587.bmp
  • $$\displaystyle \sin \phi \sin \theta =\left ( m+\frac{1}{2} \right )\frac{\lambda }{d}$$
  • $$\displaystyle d\sin \theta =m\lambda $$
  • $$\displaystyle \sin \phi -\sin \theta (m+1)\frac{\lambda }{d}$$
  • $$\displaystyle \sin \phi +\sin \theta =m\frac{\lambda }{d}$$
In Young's double slit experiment, if the widths of the slit are in the ratio $$4:9$$ , ratio of intensity of maxima to intensity of minima will be
  • $$25:1$$
  • $$9:4$$
  • $$3:2$$
  • $$81:16$$
A plane wave of monochromatic light falls normally on a uniformly thin film of oil which covers a glass plate. The wavelength of source constructive interference is observed for $$\lambda_{1} = 5000\overset {\circ}{A}$$ and $$\lambda_{2} = 10000\overset {\circ}{A}$$ and for no other wavelength in between. If $$\mu$$ of oil is $$1.25$$ and that of glass is $$1.5$$, the thickness of film will be ________ $$\mu m$$.
  • $$0.2$$
  • $$0.1$$
  • $$0.8$$
  • $$0.4$$
0:0:1


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