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question_answer1)
A slit of width\[a\]is illuminated by white light. For red light\[(\lambda =6500\,\,{AA})\], the first minima is obtained at\[\theta ={{30}^{o}}.\] Then the value of a will be [MP PMT 1987; CPMT 2002]
A)
\[3250\,\,{AA}\] done
clear
B)
\[6.5\times {{10}^{-4}}mm\] done
clear
C)
1.24 microns done
clear
D)
\[2.6\times {{10}^{-4}}cm\] done
clear
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question_answer2)
The light of wavelength\[6328\,\,{AA}\]is incident on a slit of width 0.2 mm perpendicularly, the angular width of central maxima will be [MP PMT 1987; Pb. PMT 2002]
A)
\[{{0.36}^{o}}\] done
clear
B)
\[{{0.18}^{o}}\] done
clear
C)
\[{{0.72}^{o}}\] done
clear
D)
\[{{0.09}^{o}}\] done
clear
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question_answer3)
The bending of beam of light around corners of obstacles is called [NCERT 1990; AFMC 1995; RPET 1997; RPMT 1997; CPMT 1999; JIPMER 2000]
A)
Reflection done
clear
B)
Diffraction done
clear
C)
Refraction done
clear
D)
Interference done
clear
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question_answer4)
The penetration of light into the region of geometrical shadow is called [CPMT 1999; JIPMER 2000]
A)
Polarization done
clear
B)
Interference done
clear
C)
Diffraction done
clear
D)
Refraction done
clear
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question_answer5)
A slit of size 0.15 cm is placed at 2.1 m from a screen. On illuminated it by a light of wavelength 5 ´ 10?5 cm. The width of central maxima will be [RPMT 1999]
A)
70 mm done
clear
B)
0.14 mm done
clear
C)
1.4 mm done
clear
D)
0.14 cm done
clear
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question_answer6)
A diffraction is obtained by using a beam of red light. What will happen if the red light is replaced by the blue light [KCET 2000; BHU 2001]
A)
Bands will narrower and crowd full together done
clear
B)
Bands become broader and further apart done
clear
C)
No change will take place done
clear
D)
Bands disappear done
clear
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question_answer7)
What will be the angle of diffracting for the first minimum due to Fraunhoffer diffraction with sources of light of wave length 550 nm and slit of width 0.55 mm [Pb. PMT 2001]
A)
0.001 rad done
clear
B)
0.01 rad done
clear
C)
1 rad done
clear
D)
0.1 rad done
clear
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question_answer8)
Angular width (b) of central maximum of a diffraction pattern on a single slit does not depend upon [DCE 2000; 01]
A)
Distance between slit and source done
clear
B)
Wavelength of light used done
clear
C)
Width of the slit done
clear
D)
Frequency of light used done
clear
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question_answer9)
A single slit of width 0.20 mm is illuminated with light of wavelength 500 nm. The observing screen is placed 80 cm from the slit. The width of the central bright fringe will be [AMU (Med.) 2002]
A)
1 mm done
clear
B)
2 mm done
clear
C)
4 mm done
clear
D)
5 mm done
clear
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question_answer10)
Yellow light is used in single slit diffraction experiment with slit width 0.6 mm. If yellow light is replaced by X-rays then the pattern will reveal [IIT-JEE (Screening) 1999; MP PMT 2002; KCET 2003]
A)
That the central maxima is narrower done
clear
B)
No diffraction pattern done
clear
C)
More number of fringes done
clear
D)
Less number of fringes done
clear
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question_answer11)
Which statement is correct for a zone plate and a lens [RPMT 2002]
A)
Zone plate has multi focii whereas lens has one done
clear
B)
Zone plate has one focus whereas lens has multiple focii done
clear
C)
Both are correct done
clear
D)
Zone plate has one focus whereas a lens has infinite done
clear
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question_answer12)
In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will [RPMT 2002]
A)
Increase done
clear
B)
Decrease done
clear
C)
Remain constant done
clear
D)
None of these done
clear
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question_answer13)
A plane wavefront \[(\lambda =6\times {{10}^{-7}}m)\] falls on a slit \[0.4\,mm\] wide. A convex lens of focal length \[0.8\,m\] placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum [RPMT 2001]
A)
\[6\,mm\] done
clear
B)
\[12\,mm\] done
clear
C)
\[3\,mm\] done
clear
D)
\[9\,mm\] done
clear
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question_answer14)
A zone plate of focal length \[60\,cm,\] behaves as a convex lens, If wavelength of incident light is \[6000\,\,{AA},\] then radius of first half period zone will be [RPMT 2001]
A)
\[36\times {{10}^{-8}}m.\] done
clear
B)
\[6\times {{10}^{-8}}m.\] done
clear
C)
\[\sqrt{6}\times {{10}^{-8}}m.\] done
clear
D)
\[6\times {{10}^{-4}}m.\] done
clear
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question_answer15)
Radius of central zone of circular zone plate is \[2.3\,mm.\] Wavelength of incident light is \[5893\,\,{AA}.\] Source is at a distance of \[6\,m.\] Then the distance of first image will be [RPMT 2001]
A)
\[9\,m\] done
clear
B)
\[12\,m\] done
clear
C)
\[24\,m\] done
clear
D)
\[36\,m\] done
clear
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question_answer16)
Red light is generally used to observe diffraction pattern from single slit. If blue light is used instead of red light, then diffraction pattern [RPMT 2001; BCECE 2005; CPMT 2005]
A)
Will be clearer done
clear
B)
Will contract done
clear
C)
Will expanded done
clear
D)
Will not be visualized done
clear
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question_answer17)
In the experiment of diffraction at a single slit, if the slit width is decreased, the width of the central maximum [KCET 2001]
A)
Increases in both Fresnel and Fraunhofer diffraction done
clear
B)
Decreases both in Fresnal and Fraunhofer diffraction done
clear
C)
Increases in Fresnel diffraction but decreases in Fraunhofer diffraction done
clear
D)
Decreases in Fresnel diffraction but increases is Fraunofer diffraction. done
clear
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question_answer18)
Conditions of diffraction is [RPET 2001]
A)
\[\frac{a}{\lambda }=1\] done
clear
B)
\[\frac{a}{\lambda }>>1\] done
clear
C)
\[\frac{a}{\lambda }<<1\] done
clear
D)
None of these done
clear
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question_answer19)
Light of wavelength \[589.3\,nm\] is incident normally on the slit of width \[0.1\,mm.\] What will be the angular width of the central diffraction maximum at a distance of \[1\,m\] from the slit [BHU (Med.) 1999]
A)
\[0.68{}^\circ \] done
clear
B)
\[1.02{}^\circ \] done
clear
C)
\[0.34{}^\circ \] done
clear
D)
None of these done
clear
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question_answer20)
The phenomenon of diffraction of light was discovered by [KCET 2000]
A)
Hygens done
clear
B)
Newton done
clear
C)
Fresnel done
clear
D)
Grimaldi done
clear
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question_answer21)
The radius \[r\] of half period zone is proportional to [RPMT 1998, 2002]
A)
\[\sqrt{n}\] done
clear
B)
\[\frac{1}{\sqrt{n}}\] done
clear
C)
\[{{n}^{2}}\] done
clear
D)
\[\frac{1}{n}\] done
clear
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question_answer22)
In a diffraction pattern by a wire, on increasing diameter of wire, fringe width [RPMT 1998]
A)
Decreases done
clear
B)
Increases done
clear
C)
Remains unchanged done
clear
D)
Increasing or decreasing will depend on wavelength done
clear
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question_answer23)
What will be the angular width of central maxima in Fraunhoffer diffraction when light of wavelength \[6000\,{AA}\] is used and slit width is \[12\times {{10}^{-5}}cm.\] [RPMT 2004]
A)
2 rad done
clear
B)
3 rad done
clear
C)
1 rad done
clear
D)
8 rad done
clear
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question_answer24)
When a compact disc is illuminated by a source of white light. Coloured 'lanes' are observed. This is due to [DCE 2003; AIIMS 2004]
A)
Dispersion done
clear
B)
Diffraction done
clear
C)
Interference done
clear
D)
Refraction done
clear
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question_answer25)
The diffraction effect can be observed in [J & K CET 2004]
A)
Only sound waves done
clear
B)
Only light waves done
clear
C)
Only ultrasonic waves done
clear
D)
Sound as well as light waves done
clear
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question_answer26)
If we observe the single slit Fraunhofer diffraction with wavelength l and slit width e, the width of the central maxima is 2q. On decreasing the slit width for the same l [UPSEAT 2004]
A)
q increases done
clear
B)
q remains unchanged done
clear
C)
q decreases done
clear
D)
q increases or decreases depending on the intensity of light done
clear
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question_answer27)
When light is incident on a diffraction grating the zero order principal maximum will be [KCET 2004]
A)
One of the component colours done
clear
B)
Absent done
clear
C)
Spectrum of the colours done
clear
D)
White done
clear
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question_answer28)
A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is [IIT-JEE 1994; KCET 2004]
A)
1.2 mm done
clear
B)
1.2 cm done
clear
C)
2.4 cm done
clear
D)
2.4 mm done
clear
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question_answer29)
In order to see diffraction the thickness of the film is [J&K CEE 2001]
A)
\[100\,\,{AA}\] done
clear
B)
\[10,000\,\,{AA}\] done
clear
C)
1 mm done
clear
D)
1 cm done
clear
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question_answer30)
Diffraction effects are easier to notice in the case of sound waves than in the case of light waves because [RPET 1978; KCET 1994, 2000]
A)
Sound waves are longitudinal done
clear
B)
Sound is perceived by the ear done
clear
C)
Sound waves are mechanical waves done
clear
D)
Sound waves are of longer wavelength done
clear
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question_answer31)
Direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by (a is the width of the slit) [KCET 1999]
A)
\[a\sin \theta =\frac{\lambda }{2}\] done
clear
B)
\[a\cos \theta =\frac{3\lambda }{2}\] done
clear
C)
\[a\sin \theta =\lambda \] done
clear
D)
\[a\sin \theta =\frac{3\lambda }{2}\] done
clear
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question_answer32)
A parallel monochromatic beam of light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of incident beam. At the first maximum of the diffraction pattern the phase difference between the rays coming from the edges of the slit is [IIT?JEE 1995, 98]
A)
0 done
clear
B)
\[\frac{\pi }{2}\] done
clear
C)
\[\pi \] done
clear
D)
\[2\pi \] done
clear
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question_answer33)
Diffraction and interference of light suggest [CPMT 1995; RPMT 1998]
A)
Nature of light is electro-magnetic done
clear
B)
Wave nature done
clear
C)
Nature is quantum done
clear
D)
Nature of light is transverse done
clear
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question_answer34)
A light wave is incident normally over a slit of width\[24\times {{10}^{-5}}cm\]. The angular position of second dark fringe from the central maxima is 30o. What is the wavelength of light [RPET 1995]
A)
\[6000\,\,{AA}\] done
clear
B)
\[5000\,\,{AA}\] done
clear
C)
\[3000\,\,{AA}\] done
clear
D)
\[1500\,\,{AA}\] done
clear
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question_answer35)
A parallel beam of monochromatic light of wavelength\[5000\,\,{AA}\]is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to [CBSE PMT 1993]
A)
\[0{}^\circ \] done
clear
B)
\[15{}^\circ \] done
clear
C)
\[30{}^\circ \] done
clear
D)
\[60{}^\circ \] done
clear
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question_answer36)
The condition for observing Fraunhofer diffraction from a single slit is that the light wavefront incident on the slit should be [MP PMT 1987]
A)
Spherical done
clear
B)
Cylindrical done
clear
C)
Plane done
clear
D)
Elliptical done
clear
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question_answer37)
To observe diffraction the size of an obstacle [CPMT 1982]
A)
Should be of the same order as wavelength done
clear
B)
Should be much larger than the wavelength done
clear
C)
Have no relation to wavelength done
clear
D)
Should be exactly \[\frac{\lambda }{2}\] done
clear
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question_answer38)
In the far field diffraction pattern of a single slit under polychromatic illumination, the first minimum with the wavelength \[{{\lambda }_{1}}\] is found to be coincident with the third maximum at \[{{\lambda }_{2}}\]. So
A)
\[3{{\lambda }_{1}}=0.3{{\lambda }_{2}}\] done
clear
B)
\[3{{\lambda }_{1}}={{\lambda }_{2}}\] done
clear
C)
\[{{\lambda }_{1}}=3.5{{\lambda }_{2}}\] done
clear
D)
\[0.3{{\lambda }_{1}}=3{{\lambda }_{2}}\] done
clear
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question_answer39)
Light of wavelength\[\lambda =5000\,\,{AA}\]falls normally on a narrow slit. A screen placed at a distance of 1 m from the slit and perpendicular to the direction of light. The first minima of the diffraction pattern is situated at 5 mm from the centre of central maximum. The width of the slit is
A)
0.1 mm done
clear
B)
1.0 mm done
clear
C)
0.5 mm done
clear
D)
0.2 mm done
clear
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question_answer40)
The width of the nth HPZ will be
A)
\[\sqrt{nb\lambda }\] done
clear
B)
\[\sqrt{b\lambda }\,[\sqrt{n}-\sqrt{n-1}]\] done
clear
C)
\[(\sqrt{n}\,-\,\sqrt{n-1})\] done
clear
D)
\[\frac{\sqrt{b\lambda }}{[\sqrt{n}\,-\sqrt{n-1}]}\] done
clear
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question_answer41)
A single slit of width\[a\]is illuminated by violet light of wavelength 400 nm and the width of the diffraction pattern is measured as y. When half of the slit width is covered and illuminated by yellow light of wavelength 600 nm, the width of the diffraction pattern is [KCET 2005]
A)
The pattern vanishes and the width is zero done
clear
B)
y / 3 done
clear
C)
3y done
clear
D)
None of these done
clear
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