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Mere Teacher · Previous Year Questions
JEE Main Physics · Wave Optics · Set 8 (Q211-240)
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211.
When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is ____ . (tan−1(1.52)=57.7∘), refractive indices of air and glass are 1.00 and 1.52 , respectively.)
(1)39.6∘
(2)32.3∘
(3)36.3∘
(4)42.6∘
212.
In young's double slit experiment, the fringe width is 12mm. If the entire arrangement is placed in water of refractive index 34, then the fringe width becomes (in mm)
(1)16
(2)9
(3)48
(4)12
213.
In a double-slit experiment, green light (5303Å) falls on a double slit having a separation of 19.44 µm and width of 4.05µm The number of bright fringes between the first and second diffraction minima is:
(1)09
(2)05
(3)04
(4)10
214.
Consider a tank made of glass (refractive index 1.5) with a thick bottom. It is filled with a liquid of refractive index μ. A student finds that, irrespective of what the incident angle i (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value ofμ is:
(1)35
(2)53
(3)35
(4)34
215.
For a specific wavelength 670 nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670.7 nm. The value of v is :
(1)3 x 108ms−1
(2)3 x 1010ms−1
(3)3.13 x 105ms−1
(4)4.48 x 105ms−1
216.
Three polaroid sheets P1,P2 and P3 are kept parallel to each other such that the angle between pass axes of P1 and P2 is 45∘ and that between P2 and P3 is 45∘. If unpolarised beam of light of intensity 128Wm−2 is incident on P1. What is the intensity of light coming out of P3 ?
(1)16Wm−2
(2)64Wm−2
(3)128Wm−2
(4)0
217.
A light beam is described by E=800sinω(t−cx). An electron is allowed to move normal to the propagation of light beam with a speed of 3×107ms−1. What is the maximum magnetic force exerted on the electron?
(1)1.28×10−18N
(2)1.28×10−21N
(3)12.8×10−17N
(4)12.8×10−18N
218.
In case of Fraunhoffer diffraction at a single slit the diffraction pattern on the screen is correct for which of the following statements?
(1)Central dark band having uniform brightness on either side.
(2)Central dark band having alternate dark and bright bands of decreasing intensity on either side.
(3)Central bright band having dark bands on either side.
(4)Central bright band having alternate dark and bright bands of decreasing intensity on either side.
219.
Two polarizers P1 and P2 are placed in such a way that the intensity of the transmitted light will be zero. A third polariser P3 is inserted in between P1 and P2, at particular angle between P2 and P3. The transmitted intensity of the light passing the through all three polarizers is maximum. The angle between the polarizers P2 and P3 is:
(1)π/6
(2)3π
(3)4π
(4)π/8
220.
Two poles are separated by a distance of 3.14m. The resolving power of human eye is 1 minute of an arc. The maximum distance from which he can identify the two poles distinctly is
(1)188m
(2)376m
(3)10.8km
(4)5.4km
221.
In a Young's double slit experiment, the ratio of amplitude of light coming from slits is 2 : 1. The ratio of the maximum to minimum intensity in the interference pattern is
(1)9 : 4
(2)25 : 9
(3)2 : 1
(4)9 : 1
222.
When unpolarized light is incident at an angle of 60∘ on a transparent medium from air. The reflected ray is completely polarized. The angle of refraction in the medium is
(1)30∘
(2)60∘
(3)90∘
(4)45∘
223.
A light is travelling from air into a medium. Velocity of light in a medium is reduced to 0.75 times the velocity in air. Assume that angle of incidence ' i ' is very small, the deviation of the ray is
(1)i
(2)3i
(3)4i
(4)43i
224.
The ratio of intensities at two points P and Q on the screen in a Young's double slit experiment where phase difference between two waves of same amplitude are 3π and 2π, respectively are
(1)2 : 3
(2)1 : 3
(3)3 : 1
(4)3 : 2
225.
In the Young's double slit experiment using a monochromatic light of wavelength λ, the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is :
(1)(2n+1)2λ
(2)(2n+1)4λ
(3)(2n+1)8λ
(4)(2n+1)16λ
226.
In young's double slit experiment performed using a monochromatic light of wavelengthλ, when a glass plate (μ= 1.5) of thickness xλ is introduced in the path of the one of the interfering beams, the intensity at the position where the central maximum occurred previously remains unchanged. The value of x will be:
(1)3
(2)2
(3)1.5
(4)0.5
227.
A ray of light travelling through rarer medium is incident at very small angle i on a glass slab and after refraction its velocity is reduced by 20%. The angle of deviation is
(1)8i
(2)5i
(3)2i
(4)54i
228.
In a Young's double slit experiment, the separation between the two slits is d and the wavelength of the light is λ. The intensity of light falling on slit 1 is four times the intensity of light falling on slit 2. Choose the correct choice(s).
(1)If d = λ, the screen will contain only one maximum
(2)If λ < d < 2λ, at least one more maximum (besides the central maximum) will be observed on the screen
(3)If the intensity of light falling on slit 1 is reduced so that it becomes equal to that of slit 2, the intensities of the observed dark and bright fringes will increase
(4)If the intensity of light falling on slit 2 is increased so that it becomes equal to that of slit 1, the intensities of the observed dark and bright fringes will increase
229.
The figure shows a Young's double slit experimental setup. It is observed that when a thin transparent sheet of thickness tand refractive index μ is put in front of one of the slits, the central maximum gets shifted by a distance equal to n fringe widths. If the wavelength of light used is λ, t will be:
(1)a(μ−1)2nDλ
(2)(μ−1)nλ
(3)a(μ−1)Dλ
(4)a(μ−1)2Dλ
230.
Assuming human pupil to have a radius of 0.25 cm and a comfortable viewing distance of 25 cm, the minimum separation between two objects that human eye can resolve at 500 nm wavelength is :
(1)1 μm
(2)30 μm
(3)100 μm
(4)300 μm
231.
The width of fringe is 2 mm on the screen in a double slit experiment for the light of wavelength of 400 nm. The width of the fringe for the light of wavelength 600 nm will be:
(1)4 mm
(2)2 mm
(3)1.33 mm
(4)3 mm
232.
In a Young's double slit experiment, the width of the one of the slit is three times the other slit. The amplitude of the light coming from a slit is proportional to the slit-width. Find the ratio of the maximum to the minimum intensity in the interference pattern.
(1)4:1
(2)2:1
(3)3:1
(4)1:4
233.
In a double slit experiment shown in figure, when light of wavelength 400nm is used, dark fringe is observed at P. If D=0.2m. the minimum distance between the slits S1 and S2 is________ mm.
234.
Unpolarised light of intensity 32 W m−2 passes through the combination of three polaroids such that the pass axis of the last polaroids is perpendicular to that of the pass axis of first polaroids. If intensity of emerging light is 3 W m−2, then the angle between pass axis of first two polaroids is_________
235.
A young's double slit interference arrangement with slits S1 and S2 is immersed in water (refractive index = 4/3) as shown in the figure. The positions of maxima on the surface of water are given by x2 =p2m2λ2 – d2, where λ is the wavelength of light in air (refractive index = 1), 2d is the separation between the slits and m is an integer. The value of p is
236.
As shown in figures, three identical polaroids P1, P2 and P3 are placed one after another. The pass axis of P2 and P3 are inclined at angle of 60° and 90° with respect to axis of pi. The source S has an intensity of 256m2W. The intensity of light at point is --------------------m2W.
237.
The width of one of the two slits in a Young's double slit experiment is three times the other slit. If the amplitude of the light coming from a slit is proportional to the slit-width, the ratio of minimum to maximum intensity in the interference pattern is x:4 where x is ......
238.
Sodium light of wavelengths 650 nm and 655 nm is used to study diffraction at a single slit of aperture 0.5 mm. The distance between the slit and the screen is 2.0 m. The separation between the positions of the first maxima of diffraction pattern obtained in the two cases is______x 10−5 m.
239.
If the measured angular separation between the second minimum to the left of the central maximum and the third minimum to the right of the central maximum is 30∘ in a single slit diffraction pattern recorded using 628 nm light, then the width of the slit is _______ μm.
240.
The electric field in a plane electromagnetic wave is given by E=200cos[(m0.5×103)x−(1.5×1011srad×t)]mVj^ If this wave falls normally on a perfectly reflecting surface having an area of 100cm2. If the radiation pressure exerted by the E.M. wave on the surface during a 10 minute exposure is 109xm2N. Find the value of x.
