# Solved papers for JEE Main & Advanced Physics Wave Optics / तरंग प्रकाशिकी JEE PYQ-Wave Optics

### done JEE PYQ-Wave Optics Total Questions - 67

• question_answer1) Electromagnetic waves are transverse in nature is evident by              [AIEEE 2002]

A)
polarization

B)
interference

C)
reflection

D)
diffraction

• question_answer2) To demonstrate the phenomenon of interference, we require two sources which emit radiations of              [AIEEE 2003]

A)
nearly the same frequency

B)
the same frequency

C)
different wavelength

D)
the same frequency and having a definite phase relationship

• question_answer3) The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young's double-slit experiment, is                                 [AIEEE 2004]

A)
infinite

B)
five

C)
three

D)
zero

• question_answer4) A Young's double slit experiment uses a monochromatic source. The shape of the interference fringes formed on a screen is                                               [AIEEE 2005]

A)
hyperbola

B)
circle

C)
straight line

D)
parabola

• question_answer5) When an unpolarised light^df intensity${{I}_{0}}$is incident on a polarising sheet, the intensity of the light which does not get transmitted is -                                           [AIEEE 2005]

A)
$\frac{1}{2}{{I}_{0}}$

B)
$\frac{1}{4}{{I}_{0}}$

C)
zer0

D)
${{I}_{0}}$

• question_answer6) 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?                                  [AIEEE 2005]

A)
$2{{I}_{0}}$

B)
$4{{I}_{0}}$

C)
${{I}_{0}}$

D)
$\frac{{{I}_{0}}}{2}$

• question_answer7) In a Young's double-slit experiment, the intensity at a point where the path difference is$=\frac{T}{4}=\frac{2}{4}=0.5s$ ($\pi /2$being the wavelength of the light used), is ${{v}_{a}}=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{({{10}^{-3}})}{OA}$. If $=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{({{10}^{-3}})}{\sqrt{{{(\sqrt{2})}^{2}}+{{(\sqrt{2})}^{2}}}}$ denotes the maximum intensity, ${{V}_{B}}=\frac{1}{4\pi {{\varepsilon }_{0}}}.\frac{({{10}^{-3}})}{OB}$is equal to[AIEEE 2007]

A)
$=\frac{1}{4\pi {{\varepsilon }_{0}}}.\frac{({{10}^{-3}})}{2}$

B)
${{V}_{A}}-{{V}_{B}}=0$

C)
$=\frac{\frac{1}{2}qV}{qV}=\frac{1}{2}$

D)
$I={{I}_{0}}(1-{{e}^{-t/\tau }})$

• question_answer8) A mixture of light, consisting of wavelength 590 nm and an unknown wavelength, illuminates Young's double slit and gives rise to two overlapping interference patterns on the screen. The central maximum of both lights coincide. Further, it is observed that the third bright fringe of known light coincides with the 4th bright fringe of the unknown light. From this data, the wavelength of the unknown light is:              [AIEEE 2009]

A)
393.4 nm

B)
885.0 nm

C)
442.5 nm

D)
776.8 nm

• question_answer9)  Directions: are based on the following paragraph. An initially parallel cylindrical beam travels in a medium of refractive index $\mu (I)={{\mu }_{0}}+{{\mu }_{2}}I,$where${{\mu }_{0}}$and${{\mu }_{2}}$are positive constants and I is the intensity of the light beam. The intensity of the beam is decreasing with increasing radius. The initial shape of the wave front of the beam is -                              [AIEEE 2010]

A)
planar

B)
convex

C)
concave

D)
convex near the axis and concave near the periphery

• question_answer10) At two points P and Q on a screen in Young's double slit experiment, waves from slits ${{S}_{1}}$ and ${{S}_{2}}$ have a path difference of 0 and $\frac{\lambda }{4}$respectively. The ratio of intensities at P and Q will be:[AIEEE 11-05-2011]

A)
$2:1$

B)
$\sqrt{2}:1$

C)
$4:1$

D)
$3:2$

• question_answer11) In a Young's double slit experiment, the two slits act as coherent sources of waves of equal amplitude A and wavelength $\lambda .$ In another experiment with the same arrangement the two slits are made to act as incoherent sources of waves of same amplitude and wavelength. If the intensity at the middle point of the screen in the first case is ${{I}_{1}}$ and in the second case is ${{I}_{2}},$ then the ratio $\frac{{{I}_{1}}}{{{I}_{2}}}$is: [AIEEE 11-05-2011]

A)
2

B)
1

C)
0.5

D)
4

• question_answer12)  Statement -1 : On viewing the clear blue portion of the sky through a Calcite Crystal, the intensity of transmitted light varies as the crystal is rotated. Statement - 2: The light coming from the sky is polarized due to scattering of sun light by particles in the atmosphere. The scattering is largest for blue light                                       [AIEEE 11-05-2011]

A)
Statement-1 is true, statement-2 is false.

B)
Statement-1 is true, Statement-2 is true, Statement-2 is the correct explanation of statment-1

C)
Statement-1 is true, Statement-2 is true, Statement-2 is not the correct explanation of statement-1

D)
Statement-1 is false, Statement-2 is true.

• question_answer13) In Young's double slit experiment, one of the slit is wider than other, so that amplitude of the light from one slit is double of that from other slit. If ${{I}_{m}}$ be the maximum intensity, the resultant intensity I when they interfere at phase difference $\phi$ is given by:            [AIEEE 2012]

A)
$\frac{{{I}_{m}}}{9}(4+5\cos \phi )$

B)
$\frac{{{I}_{m}}}{3}\left( 1+2{{\cos }^{2}}\frac{\phi }{2} \right)$

C)
$\frac{{{I}_{m}}}{5}\left( 1+4{{\cos }^{2}}\frac{\phi }{2} \right)$

D)
$\frac{{{I}_{m}}}{9}\left( 1+8{{\cos }^{2}}\frac{\phi }{2} \right)$

• question_answer14) In a Young's double slit experiment with light of wavelength$\lambda ,$ fringe pattern on the screen has fringe width $\beta .$ When two thin transparent glass (refractive index $\mu$) plates of thickness ${{t}_{1}}$ and ${{t}_{2}}$ $({{t}_{1}}>{{t}_{2}})$are placed in the path of the two beams respectively, the fringe pattern will shift by a distance                                       [JEE ONLINE 07-05-2012]

A)
$\frac{\beta (\mu -1)}{\lambda }\left( \frac{{{t}_{1}}}{{{t}_{2}}} \right)$

B)
$\frac{\mu \beta }{\lambda }\frac{{{t}_{1}}}{{{t}_{2}}}$

C)
$\frac{\beta \left( \mu -1 \right)}{\lambda }\left( {{t}_{1}}-{{t}_{2}} \right)$

D)
$\left( \mu -1 \right)\frac{\lambda }{\beta }\left( {{t}_{1}}+{{t}_{2}} \right)$

• question_answer15) Two polaroids have their polarizing directions parallel so that the intensity of a transmitted light is maximum. The angle through which either Polaroid must be turned if the intensity is to drop by one-half is [JEE ONLINE 07-05-2012]

A)
135°

B)
90°

C)
120°

D)
180°

• question_answer16)  Which of the following processes play a part in the formation of a rainbow?[JEE ONLINE 07-05-2012] (i)   Refraction (ii) Total internal reflection (iii) Dispersion (iv) Interference

A)
(i), (ii) and (iii)

B)
(i) and (ii)

C)
(i), (ii) and (iv)

D)
(iii) and (iv)

• question_answer17) The first diffraction minimum due to the single slit diffraction is seen at $\theta ={{30}^{o}}$for a light of wavelength 5000 A falling perpendicularly on the slit. The width of the slit is [JEE ONLINE 12-05-2012]

A)
$2.5\times {{10}^{-5}}cm$

B)
$1.25\times {{10}^{-5}}cm$

C)
$10\times {{10}^{-5}}cm$

D)
$5\times {{10}^{-5}}cm$

• question_answer18) We wish to make a microscope with the help of two positive lenses both with a focal length of 20 mm each and the object is positioned 25 mm from the objective lens. How far apart the lenses should be so that the final image is formed at infinity?    [JEE ONLINE 12-05-2012]

A)
20mm

B)
100mm

C)
120mm

D)
80mm

• question_answer19) The maximum number of possible interference maxima for slit separation equal to 1. 8A,, where X is the wavelength of light used, in a Young's double slit experiment is [JEE ONLINE 12-05-2012]

A)
zero

B)
3

C)
infinite

D)
5

• question_answer20)  Two coherent plane light waves of equal amplitude makes a small angle a (« 1) with each other. They fall almost normally on a screen. If $\lambda$ the wavelength of light waves, the fringe width $\Delta x$of interference patterns of the two sets of waves on the screen is                                              [JEE ONLINE 19-05-2012]

A)
$\frac{2\lambda }{\alpha }$

B)
$\frac{\lambda }{\alpha }$

C)
$\frac{\lambda }{\left( 2\alpha \right)}$

D)
$\frac{\lambda }{\sqrt{\alpha }}$

• question_answer21) In Young's double slit interference experiment, the slit widths are in the ratio 1 : 25. Then the ratio of intensity at the maxima and minima in the interference pattern is [JEE ONLINE 26-05-2012]

A)
3 : 2

B)
1 : 25

C)
9 : 4

D)
1 : 5

• question_answer22)  A beam of unpolarised light of intensity${{I}_{0}}$is passed through a polaroid A and then through another polaroid B which is oriented so that its principal plane makes an angle of$45{}^\circ$ relative to that of A. The intensity of the emergent light is:                                                [JEE MAIN 2013]

A)
${{I}_{0}}$

B)
${{I}_{0}}/2$

C)
${{I}_{0}}/4$

D)
${{I}_{0}}/8$

• question_answer23)  Two coherent point sources${{S}_{1}}$and${{S}_{2}}$are separated by a small distance 'd' as shown. The fringes obtained on the screen will be:                                  [JEE MAIN 2013]

A)
points

B)
straight lines

C)
semi−circles

D)
concentric circles

• question_answer24)  A person lives in a high-rise building on the bank of a river 50 m wide. Across the river is a well-lit tower of height 40 m. When the person, who is at a height of 10 m, looks through a polarizer at an appropriate angle at light of the tower reflecting from the river surface, he notes that intensity of light coming from distance X from his building is the least and this corresponds to the light coming from light bulbs at height Y on the tower. The values of X and Y are respectively close to (refractive index of water$\simeq \frac{4}{3}$) [JEE ONLINE 09-04-2013]

A)
25 m, 10 m

B)
13 m, 27 m

C)
22 m, 13 m

D)
17 m, 20 m

• question_answer25)  A ray of light of intensity I is incident on a parallel glass slab at point A as shown India gram. It undergoes partial reflection and refraction. At each reflection, 25% of incident energy is reflected. The rays AB and A B undergo interference. The ratio of ${{\operatorname{I}}_{\max }}$ and${{\operatorname{I}}_{\min }}$ is: [JEE ONLINE 09-04-2013]

A)
49 : 1

B)
7 : 1

C)
4 : 1

D)
8 : 1

• question_answer26)  This question has Statement-1 and Statement-2. Of the four choices given after the Statements, choose the one that best describes the two Statements. [JEE ONLINE 22-04-2013] Statement 1: In Youngs double slit experiment, the number of fringes observed in the filed of view is small with longer wave length of light and is large with shorter wave length of light. Statement 2: In the double slit experiment the fringe width depends directly on the wave length of light.

A)
Statement 1 is true Statement 2 is true and the Statement 2 is not the correct explanation of the Statement 1

B)
Statement 1 is false and the Statement 2 is true

C)
Statement 1 true and statement 2 is true and the Statement 2 is true explanation of the Statement 1

D)
Statement 1 is true and the Statement 2 is false

• question_answer27) A thin glass plate of thickness $\frac{2500}{3}\lambda (\lambda$ is wavelength of light used) and refractive index  $\mu =1.5$ is inserted between one the slits and the screen Yongs double slit experiment. At a point on the screen equidistant from the slits, the ratio of the intensities before and after the introduction of the glass plate is:                                            [JEE ONLINE 25-04-2013]

A)
2 : 1

B)
1 : 4

C)
4 : 1

D)
4 : 3

• question_answer28) The source that illuminates the double-slit in doubleslit interference experiment emits two distinct monochromatic waves of wavelength 500 nm and 600 nm each of them producing its own pattern on the screen. At the central point of the pattern when path difference is zero, maxima of booth the patterns coincide and the resulting interference pattern is most distinct at the region of zero path difference. But as one moves out of this central region, the two fringe systems are gradually out of step such that maximum due to one wave length coincides with the minimum due to the other and the other and the combined fringe system becomes completely indistinct. This may happen when path difference in nm is:                                      [JEE ONLINE 25-04-2013]

A)
2000

B)
3000

C)
1000

D)
1500

• question_answer29)  This question has Statement -1 and Statement -2 Of the four choices given after the Statements, choose the one that best describes the two Statement.            [JEE ONLINE 25-04-2013] Statement-1: Out of radio waves and microwaves, the radio waves undergo more diffraction. Statement-2: Radio waves have greater frequency compared to microwaves

A)
Statement -1 is true, Statement -2 is true and Statement -2 is the correct explanation of Statement 1.

B)
Statement -1 is false, Statemnt-2 is true.

C)
Statement -1 is true, Statement -2 is true.

D)
Statement -1 is true, Statement 2 is true but Statement-2 is not the correct explanation of Statement -1.

• question_answer30) Two beams, A and B, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of polaroid through 30° makes the two beams appear equally bright. If the initial intensities of the two beams are ${{\text{I}}_{\text{A}}}$ and ${{\text{I}}_{\text{B}}}$respectively, then $\frac{{{\text{I}}_{\text{A}}}}{{{\text{I}}_{\text{B}}}}$equals: [JEE MAIN 2014]

A)
1

B)
$\frac{1}{3}$

C)
3

D)
$\frac{3}{2}$

• question_answer31)  Using monochromatic light of wavelength $\lambda ,$ an experimentalist sets up the Youngs double slit experiment in three ways as shown. If she observes that $y=\beta ',$ the wavelength of light used is:                  [JEE ONLINE 09-04-2014]

A)
520 nm

B)
540 nm

C)
560 nm

D)
580 nm

• question_answer32) Two monochromatic light beams of intensity 16 and 9 units are interfering. The ratio of intensities of bright and dark parts of the resultant pattern is:  [JEE ONLINE 11-04-2014]

A)
$\frac{16}{9}$

B)
$\frac{4}{3}$

C)
$\frac{7}{1}$

D)
$\frac{49}{1}$

• question_answer33)  Interference pattern is observed at P due to superimposition of two rays coming out from a source S as shown in the figure. The value of l for which maxima is obtained at P is:   [JEE ONLINE 12-04-2014] (R is perfect reflecting surface)

A)
$1=\frac{1n\lambda }{\sqrt{3}-1}$

B)
$1=\frac{(2n-1)\lambda }{2\left( \sqrt{3}-1 \right)}$

C)
$1=\frac{(2n-1)\lambda \sqrt{3}}{4\left( 2-\sqrt{3} \right)}$

D)
$1=\frac{(2n-1)\lambda }{\sqrt{3}-1}$

• question_answer34) 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 6600 Å, then wavelength of first maximum will be: [JEE ONLINE 12-04-2014]

A)
3300Å

B)
4400Å

C)
5500Å

D)
6600Å

• question_answer35) A ray of light is incident from a denser to a rarer medium. The critical angle for total internal reflection is ${{\theta }_{iC}}$and Brewsters angle of incidence is ${{\theta }_{iB}},$ such that $\sin {{\theta }_{iC}}/\sin {{\theta }_{iB}}$$=\eta =1.28.$ = h = 1.28. The relative refractive index of the two media is:                                                   [JEE ONLINE 19-04-2014]

A)
0.2

B)
0.4

C)
0.8

D)
0.9

• question_answer36)  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:                                                     [JEE ONLINE 19-04-2014]

A)
3

B)
6

C)
12

D)
24

• question_answer37) On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens principle leads us to conclude that as it travels, the light beam:          [JEE MAIN 2015]

A)
bends downwards

B)
bends upwards

C)
becomes narrower

D)
goes horizontally without any deflection

• question_answer38)  A parallel beam of electrons travelling in x-direction falls on a slit of width d (see figure). If after passing the slit, an electron acquires momentum ${{p}_{y}}$ in the y-direction then for a majority of electrons passing through the slit (h is Planck's constant): [JEE ONLINE 10-04-2015]

A)
$|{{p}_{y}}|d>h$

B)
$|{{p}_{y}}|d>>h$

C)
$|{{p}_{y}}|d<h$

D)
$|{{p}_{y}}|d\simeq h$

• question_answer39) In a Young's double slit experiment with light of wavelength$\lambda$the separation of slits is d and distance of screen is D such that $D>>d>>\lambda .$If the Fringe width is $\beta ,$ the distance from point of maximum intensity to the point where intensity falls to half of maximum intensity on either side is :[JEE MAIN 11-04-2015]

A)
$\frac{\beta }{2}$

B)
$\frac{\beta }{4}$

C)
$\frac{\beta }{3}$

D)
$\frac{\beta }{6}$

• question_answer40) Unpolarized light of intensity in is incident on surface of a block of glass at Brewster's angle. In that case, which one of the following statements is true?      [JEE MAIN 11-04-2015]

A)
transmitted light is partially polarized with intensity ${{I}_{0}}/2.$

B)
transmitted light is completely polarized with intensity less than ${{I}_{0}}/2.$

C)
reflected light is completely polarized with intensity less than ${{I}_{0}}/2.$

D)
reflected light is partially polarized with intensity ${{I}_{0}}/2.$

• question_answer41) The box of a pin hole camera, of length L, has a hole of radius a. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength$\lambda$ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say ${{b}_{\min }}$) when:-                       [JEE MAIN - I 3-4-2016]

A)
$a=\frac{{{\lambda }^{2}}}{L}$and${{b}_{\min }}=\sqrt{4\lambda L}$

B)
$a=\frac{{{\lambda }^{2}}}{L}$and${{b}_{\min }}=\left( \frac{2{{\lambda }^{2}}}{L} \right)$

C)
$a=\sqrt{\lambda L}$and${{b}_{\min }}=\left( \frac{2{{\lambda }^{2}}}{L} \right)$

D)
$a=\sqrt{\lambda L}$and${{b}_{\min }}=\sqrt{4\lambda L}$

• question_answer42) In Young's double slit experiment, the distance between slits and the screen is 1.0 m and monochromatic light of 600 nm is being used. A person standing near the slits is looking at the fringe pattern. When the separation between the slits is varied, the interference pattern disappears for a particular distance ${{d}_{0}}$ between the slits. If the angular resolution of the eye is$\frac{{{1}^{o}}}{60}$the value of ${{d}_{0}}$ is close to [JEE ONLINE 09-04-2016]

A)
2 mm

B)
1 mm

C)
3mm

D)
4 mm

• question_answer43) In a Young's double slit experiment, slits are separated by 0.5 mm, and the screen is placed 150 cm away. A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes on the screen. The least distance from the common central maximum to the point where the bright fringes due to both the wavelengths coincide is:                                            [JEE Main 2017]

A)
9.75 mm

B)
15.6 mm

C)
1.56 mm

D)
7.8 mm

• question_answer44) An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer?[JEE Main 2017] (speed of light$=3\times {{10}^{8}}\,m{{s}^{-1}}$)

A)
17.3 GHz

B)
15.3 GHz

C)
10.1 GHz

D)
12.1 GHz

• question_answer45) A single slit of width b is illuminated by a coherent monochromatic light of wavelength $\lambda$.If the second and fourth minima in the diffraction pattern at a distance 1 m from the slit are at 3 cm and 6 cm respectively from the central maximum, what is the width of the central maximum ? (i.e., distance between first minimum on either side of the central maximum)       [JEE Online 08-04-2017]

A)
4.5 cm

B)
1.5 cm

C)
6.0 cm

D)
3.0 cm

• question_answer46) Let the refractive index of a denser medium with respect to a rarer medium be ${{n}_{12}}$and its c critical angle be ${{\theta }_{C}}.$At an angle of incidence A when light is travelling from denser medium to rarer medium, a part of the light is reflected and the rest is refracted and the angle between reflected and refracted rays is 90°. Angle A given by  [JEE Online 08-04-2017]

A)
${{\tan }^{-1}}(\sin {{\theta }_{C}})$

B)
$\frac{1}{{{\tan }^{-1}}(\sin {{\theta }_{C}})}$

C)
${{\cos }^{-1}}(\sin {{\theta }_{C}})$

D)
$\frac{1}{{{\cos }^{-1}}(\sin {{\theta }_{C}})}$

• question_answer47) A single slit of width 0.1 mm is illuminated by a parallel beam of light of wavelength $6000\overset{\text{o}}{\mathop{\text{A}}}\,$ and diffraction bands are observed on a screen 0.5 m from the slit. The distance of the third dark band from the central bright band is                               [JEE Online 09-04-2017]

A)
9 mm

B)
3 mm

C)
4.5 mm

D)
1.5 mm

• question_answer48) Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed behind A. The intensity of light beyond B is found to be$\frac{\text{I}}{\text{2}}$. Now another identical polarizer C is placed between A and B. The intensity beyond B is now found to be $\frac{\text{I}}{8}$. The angle between polarizer A and C is: [JEE Main Online 08-04-2018]

A)
$45{}^\circ$

B)
$60{}^\circ$

C)
$0{}^\circ$

D)
$30{}^\circ$

• question_answer49) The angular width of the central maximum in a single slit diffraction pattern is $\text{60 }\!\!{}^\circ\!\!\text{ }$. The width of the slit is $\text{1}\,\,\,\mu \text{m}$. The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it. Young's fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe width is 1 cm, what is slit separation distance? (i.e. distance between the centres of each slit.)               [JEE Main Online 08-04-2018]

A)
$75\mu m$

B)
$100\mu m$

C)
$25\mu m$

D)
$50\mu m$

• question_answer50) Light wavelength $550nm$ falls normally on a slit of width$22.0\times {{10}^{-5}}cm$. The angular position of the second minima from the central maximum will be (in radians) [JEE Online 15-04-2018]

A)
$\frac{\pi }{8}$

B)
$\frac{\pi }{12}$

C)
$\frac{\pi }{4}$

D)
$\frac{\pi }{6}$

• question_answer51)  A plane polarized light is incident on a polariser with its pass axis making angle $\theta$ with x-axis, as shown in the figure. At four different values of $\theta ,\theta =8{}^\circ ,38{}^\circ ,188{}^\circ$and $218{}^\circ$, the observed intensities are same. What is the angle between the direction of polarization and x-axis [JEE Online 15-04-2018 (II)]

A)
$203{}^\circ$

B)
$45{}^\circ$

C)
$98{}^\circ$

D)
$128{}^\circ$

• question_answer52) Unpolarized light of intensity I is incident on a system of two polarizes, A followed by B. The intensity of emergent light is$I/2.$ If a third polarizer C is placed between A and B, the intensity of emergent light is reduced to I/3. The angle between the polarizers A and C is $\theta .$Then [JEE Main Online 16-4-2018]

A)
$\cos \theta ={{\left( \frac{2}{3} \right)}^{1/4}}$

B)
$\cos \theta ={{\left( \frac{1}{3} \right)}^{1/4}}$

C)
$\cos \theta ={{\left( \frac{1}{3} \right)}^{1/2}}$

D)
$\cos \theta ={{\left( \frac{2}{3} \right)}^{1/2}}$

• question_answer53) Two coherent sources produce waves of different intensities which interfere. After interference, the ratio of the maximum intensity to the minimum intensity is 16.             The intensity of the waves are in the ratio:  [JEE Main 09-Jan-2019 Morning]

A)
25 : 9

B)
4 : 1

C)
5 : 3

D)
16 : 9

• question_answer54)  The magnetic field associated with a light wave is given, at the origin, by $B\text{ }=\text{ }{{B}_{0}}$ $[sin(3.14\,\times \,\,{{10}^{7}})ct+sin(6.28\,\,\times \,{{10}^{6}})ct]$ If this light falls on a silver plate having a work function of 4.7 eV, what will be the maximum kinetic energy of the photo electrons? $\left( c=3\text{ }\times \text{ }{{10}^{8}}\text{ }m{{s}^{-\,1}},\text{ }h\,\,=\,\,6.6\,\,\times \,\,{{10}^{-34}}\,J-s \right)$ [JEE Main 09-Jan-2019 Evening]

A)

B)

C)

D)

• question_answer55) A closed organ pipe has a fundamental frequency of 1.5 kHz. The number of overtones that can be distinctly heard by a person with this organ pipe will be (Assume that the highest frequency a person can hear is 20,000 Hz) [JEE Main 10-Jan-2019 Evening]

A)
4

B)
7

C)
6

D)
5

• question_answer56) Equation   of travelling wave   on   a stretched string of linear density 5 g/m is  where distance and time are measured in SI units. The tension in the string is- [JEE Main 11-Jan-2019 Morning]

A)
10 N

B)
7.5 N

C)
5 N

D)
12.5 N

• question_answer57) A travelling harmonic wave is represented by the equation where x and t are in meter and t is in seconds. Which of the following is a correct statement about the wave? [JEE Main 12-Jan-2019 Morning]

A)
The wave is propagating along the positive x-axis with speed .

B)
The wave is propagating along the positive x-axis with speed .

C)
The wave is propagating along the negative x-axis with speed .

D)
The wave is propagating along the negative x-axis with speed .

• question_answer58) A resonance tube is old and has jagged end. It is still used in the laboratory to determine velocity of sound in air. A tuning fork of frequency 512 Hz produces first resonance when the tube is filled with water to a mark 11 cm below a reference mark, near the open end of the tube. The experiment is repeated with another fork of frequency 256 Hz which produces first resonance when water reaches a mark 27 cm below the reference mark. The velocity of sound in air, obtained in the experiment, is close to-              [JEE Main 12-Jan-2019 Evening]

A)

B)

C)

D)

• question_answer59) A string is clamped at both the ends and it is vibrating in its 4th harmonic. The equation of the stationary wave is . The length of the string is : (All quantities are in SI units.)  [JEE Main 9-4-2019 Morning]

A)
20 m

B)
80 m

C)
60 m

D)
40 m

• question_answer60) energy density of sunlight is normally incident on the surface of a solar panel. Some part of incident energy (25%) is reflected from the surface and the rest is absorbed. The force exerted on surface area will be close to :- [JEE Main 9-4-2019 Afternoon]

A)

B)

C)

D)

• question_answer61) Light is incident normally on a completely absorbing surface with an energy flux of if the surface has an area of the momentum transferred to the surface in 40 min time duration will be : [JEE Main 10-4-2019 Afternoon]

A)

B)

C)

D)

• question_answer62) Visible light of wavelength $6000\times {{10}^{8}}\text{ }cm$ falls normally on a single slit and produces a diffraction pattern. It is found that the second diffraction minimum is at $60{}^\circ$ from the central maximum. If the first minimum is produced at ${{\theta }_{1}}$, then ${{\theta }_{1}}$ is close to [JEE MAIN Held on 07-01-2020 Morning]

A)
$25{}^\circ$

B)
$30{}^\circ$

C)
$20{}^\circ$

D)
$45{}^\circ$

• question_answer63) A polarizer-analyser set is adjusted such that the intensity of light coming out of the analyser is just 10% of the original intensity. Assuming the polarizer - analyser set does not absorb any light, the angle by which the analyser need to be rotated further to reduced the output intensity to be zero, is [JEE MAIN Held on 07-01-2020 Morning]

A)
$71.6{}^\circ$

B)
$45{}^\circ$

C)
$90{}^\circ$

D)
$18.4{}^\circ$

• question_answer64) A stationary observer receives sound from two identical tuning forks, one of which approaches and the other one recedes with the same speed (much less than the speed of sound). The observer hears 2 beats/sec. The oscillation frequency of each tuning fork is ${{v}_{0}}=1400$ Hz and the velocity of sound in air 350 m/s. The speed of each tuning fork is close to: [JEE MAIN Held on 07-01-2020 Evening]

A)
$\frac{1}{4}\,m/s$

B)
$\frac{1}{2}\,m/s$

C)
$1\,m/s$

D)
$\frac{1}{8}\,m/s$

• question_answer65) In a Youngs double slit experiment, the separation between the slits is 0.15 mm. In the experiment, a source of light of wavelength 589 nm is used and the interference pattern is observed on a screen kept 1.5 m away. The separation between the successive bright fringes on the screen is: [JEE MAIN Held on 07-01-2020 Evening]

A)
3.9 mm

B)
6.9 mm

C)
5.9 mm

D)
4.9 mm

• question_answer66) In a double-slit experiment, at a certain point on the screen the path difference between the two interfering waves is $\frac{1}{8}th$ of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is   [JEE MAIN Held on 08-01-2020 Evening]

A)
0.568

B)
0.760

C)
0.853

D)
0.672

• question_answer67) In a Youngs double slit experiment 15 fringes are observed on a small portion of the screen when light of wavelength 500 nm is used. Ten fringes are observed on the same section of the screen when another light source of wavelength $\lambda$ is used. Then the value of $\lambda$ is (in nm) _______. [JEE MAIN Held on 09-01-2020 Evening]