JEE Main Previous Year Papers Questions With Solutions Physics Optics
Multiple Choice with ONE correct answer
1.When a ray of light enters a glass slab from air ! [1980-1 mark]
a) its wavelength decreases.
b) its wavelength increases.
c) its frequency increases.
d) neither its wavelength nor its frequency changes.
3.In Young’s double slit experiment, the separation between the slits is halved and the distance
between the slits and the screen is doubled. The finge width is [1981-2 marks]
a)unchanged b) halved
c) doubled d) quadrupled
Ans.(a) Total internal reflection occurs when the ray of light travels from denser medium to rarer medium and the angle of incidence is greater than the critical angle.
6.Two coherent monochromatic light beams of intensities I and 41 are superposed. The maximum and minimum possible intensities in the resulting beam are [1988-1 mark]
a)51 and I b) 51 and 31
c) 91 and I d) 91 and 31
7.Spherical aberration, in a thin lens, can be reduced by [1994-1 mark]
a)using a monochromatic light ‘
b)using a doublet combination
c)using a circular annular mask over the lens
d)increasing the size of the lens.
Ans.(c) Spherical aberration is caused because the marginal rays and the paraxial rays incident on a lens are brought to focus at different points.To reduce spherical aberration, the marginal rays are blocked by using a circular annular mask over the lens.
8.A beam of light of wavelength 600nm, from a distant source, falls on a single slit 1 mm wide and a resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of central bright fringe is [1994-1 mark]
a)1.2 cm b) 1.2 mm
c) 2.4 cm d) 2.4 mm
9.An isosceles prism of angle 120 ° has a refractive index 1.44. Two parallel monochromatic rays enter the prism, parallel to each other in air, as shown. The rays which emerge from the opposite faces [1995-2 marks]
10.The focal lengths of the objective and the eye piece of a compound microscope are 2.0 cm and 3.0 cm, respectively. The distance between the objective and the eyepiece is 15.0 cm. The final image formed by the eyepiece is at infinity. The two lenses are thin. The distance, in cm, of the object and the image produced by the objective, measured from the objective lens, are respectively.[1995-2 marks]
a)2.4 and 12.0 b) 2.4 and 15.0
c) 2.0 and 12.0 d) 2.0 and 3.0
Ans.(a) The eyepiece forms the final image at infinity. Its object should therefore lie at its focus.â€˜F’ denotes focus of eyepiece. â€˜I’ denotes image formed by the objective lens which serves as object for eye piece. It should be at 3 cm from eyepiece.
11.Consider Fraunhofer diffraction pattern obtained with a single slit illuminated at normal incidence. At the angular position of the first diffraction minimum, the phase difference (in radian) between the wavelets from the opposite edges of the slit is 
13.An eye specialist prescribes spectacles having a combination of convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm . The power of this lens combination, in dioptre is [1997-1 mark]
a)+1.5 b) -1.5 c) +6.67 d) -6.67
14.A concave lens of glass, refractive index 1.5, has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75, it will behave as a [1999-2 marks]
a)convergent lens of focal length 3.5R
b)convergent lens of focal length 3.0 R.
c)divergent lens of focal length 3.5 R
d)divergent lens of focal length 3.0 R
15.Yellow light is used in a single slit diffraction experiment with slit width of 0.6 mm. If yellow light is replaced by X-rays, then the observed pattern will reveal, [1999-2 marks]
a)that the central maximum in narrower
b)more number of fringes
c)less number of fringes
d)no diffraction pattern.
16.A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plate as shown in figure. The observed interference fringes from this combination shall be [1999-2 marks]
d)having fringe spacing which increases as we go outwards.
Ans.(a) Locus of equal path difference consists in the lines running parallel to the axis of the cylinder. Hence fringes obtained are straight.
18.A point source of light B is placed at a distance L in front of the centre of a mirror of width d hung vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from it as shown in figure. The greatest distance over which he can see the image of the light source in the mirror is [2002-2 marks]
Ans.(a) Rays come out only from the surface CD when the light is incident at the surface AB of the slab. It means that rays after refraction from AB undergo total internal reflection at surface AD of the slab.
21.In a double slit experiment, instead of taking slits of equal widths, one slit is made twice as wide as the other. Then, in the interference pattern[2000-2 marks]
a)the intensities of both the maxima and the minima increase.
b)the intensity of the maxima increases and the minima has zero intensity.
c)the intensity of the maxima decreases and that of the minima increases.
d)the intensity of the maxima decreases and the minima has zero intensity.
22.In a compound microscope, the intermediate image is [2000-2 marks]
a)virtual, erect and magnified
b)real, erect and magnified
c)real, inverted and magnified
d)virtual, erect and reduced.
Ans.(c) The intermediate image in a compound microscope is real, inverted and magnified.
23.Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the beams is p/2 at point A and p at point B. Then the difference between the resultant intensities at A and B is [JEE (Scr.) 2001-2M]
a) 2I b) 4I c) 5I d) 7I
24.In young’s double slit experiment, 12 fringes are observed to be formed in a certain segment of the screen when light of wavelength 600 nm is used. If the wavelength of light is changed to 400 nm, number of fringes observed in the same segment of the screen is given by [2001-1 mark]
a) 12 b) 18 c) 24 d) 30
26.A given ray of light suffers minimum deviation in an equilateral prism P. Additional prism Q and R of identical shape and of the same material as P are now added as shown in the figure. The ray will now suffer [2001-2 marks]
c)same deviation as before
d)total internal reflection
27.An observer can see through a pin-hole the top end of a thin rod of height h, placed as shown in the figure. The beaker height is 3h and its radius h. When the beaker is filled with a liquid up to a height 2h, he can see the lower end of the rod. Then the refractive index of the liquid is[2002-2 marks]
28.Which one of the following spherical lenses does not exhibit dispersion? The radii of curvature of the surfaces of the lenses are as given in the diagrams. [2002-2 marks]
30.Two plane mirrors A and B are aligned parallel to each other, as shown in the figure. A light ray is incident at an angle of 30 ° at a point just inside one end of A. The plane of incidence coincides with the plane of the figure. The maximum number of times the ray undergoes reflections (including the first one) before it emerges out is [2002-2 marks]
31.In the given diagram, CP represents a wavefront and AO and BP, the corresponding two rays. Find the condition in q for constructive interference at P between the ray BP and reflected ray OP.
32.The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm. If a concave lens of focal length 20 cm is placed between the covex lens and the image at a distance of 26 cm from the convex lens,calculate the new size of the image[2003-2 marks]
a) 1.25 cm b) 2.5 cm c) 1.05 cm d) 2 cm
34.A beam of white light is incident on glass air interface from glass to air such that green light just suffers total internal reflection. The colours of the light which will come out to air are[2004-2 marks]
a)violet, indigo, blue
b)all colours except green
c)yellow, orange, red
d) white light
35.An equilateral prism is placed on a horizontal surface. A ray PQ is incident onto it. For minimum deviation. [2004-2 marks]
a)PQ is horizontal
b)QR is horizontal
c)RS is horizontal
d)any one will be horizontal
36.Monochromatic light of wavelength 400 nm and 560 nm are incident simultaneously and normally on double slit apparatus whose slit separation is 0.1 mm and screen distance is lm. Distance between areas of total darkness will be [2004-2 marks]
a) 4mm b) 5.6mm c) 14mm d) 28mm
Ans.(d) At the area of total darkness, in double slit apparatus, minima will occur for both the wavelengths which are incident simultaneously and normally.
37.A source emits sound of frequency 600 Hz inside water. The frequency heard in air will be equal to (velocity of sound in water = 1500 m/s, velocity of sound in air = 300 m/s) [2004-2 m]
a) 3000Hz b)120Hz c) 600Hz d) 6000Hz
Ans.(c) Frequency of sound = 600 Hz inside water. Fre quency of a wave depends on the source and it does not change during refraction when wave trav els from one medium to another.
Frequency heard in air = 600 Hz.
38.A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of the virtual image from the surface is [2004-2 marks]
a) 6 cm b) 4 cm c) 12 cm d) 9 cm
40.A convex lens is in contact with concave lens. The magnitude of the ratio of their focal lengths is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths? [2005-2 marks]
a) -15,10 b) -10,15 c) 75, 50 d) -75,50
42.Focal length of the plano-convex lens is 15 cm. A small object is placed at A as shown in the figure. The plane surface is silvered. The image will form at [2006-3 marks]
a)60 cm to the left of lens
b)12 cm to the left of lens
c)60 cm to the right of lens
d)30 cm to the left of lens
43.The graph shows relationship between object distance and image distance for an equiconvex lens. Then, focal length of the lens is. [2006-3 marks]
a)50 ±0.05 cm
Ans.(b) Rays of light from sun are incident upon a biconvex lens. Sun is at infinity and incident rays form a parallel beam.The beam is brought to convergence in the focal plane of the lens. AB is image of the sun.
Ans.(c) The ray is incident on the interface of a rarer medium (air) from a denser medium (water), and the angle of incidence is less than the critical angle. The ray will be partly refracted and partly reflected
Ans.(b) On shifting the eye towards left, the image will appear to the right of the object pin if the image distance is more than the object distance and the image is real. This happens when the object lies between the focus and the centre of curvature, f < x<2f.
47.Two beams of red and violet colours are made to pass separately through a prism (angle of the prism is 60 °). In the position of minimum deviation, the angle of refraction will be 
a)30 ° for both the colours
b)greater for the violet colour
c)greater for the red colour
d)equal but not 30 ° for both the colours
49.A ball is dropped from a height of 20 m above the surface of water in a lake. The refractive index of water is 4/3. A fish inside the lake, in the line of fall of the ball, is looking at the ball. At an instant, when the ball is 12.8 m above the water surface, the fish sees the speed of ball as [Take g = 10/s2],
a)9 m/s b) 12 m/s c) 16 m/s d) 21.33 m/s
50.A biconvex lens of focal length 15 cm is in front of a plane mirror. The distance between thelens and the mirror is 10 cm. A small object is kept at a distance of 30 cm from the lens. The final image is
a)virtual and at a distance of 16 cm from the mirror
b)real and at a distance of 16 cm from the mirror
c)virtual and at a distance of 20 cm from the mirror
d)real and at a distance of 20 cm from the mirror
Multiple Choice with ONE or More Than ONE correct answer
Ans.(c) 100% reflection or transmission not possible
52.In Young’s double slit experiment, the interference pattern is found to have an intensity ratio between the bright and dark fringes as 9. This implies that[1982-3 marks]
a) the intensities at the screen due to the two slits are 5 units and 4 units respectively
b) the intensities at the screen due to the two slits are 4 units and 1 unit respectively
c) the amplitude ratio is 3
d) the amplitude of ratio is 2.
53.A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is [1982-3 marks]
a) -1.5 dioptre b) -6.5 dioptre
c)+6.5 dioptre d) +6.67 dioptre
55.A converging lens is used to form an image on a screen. When the upper half of the lens is covered by an opaque screen [1986-2 marks]
a)half the image will disappear
b)complete image will be formed
c)intensity of the image will increase
d)intensity of the image will decrease
Ans.(b), (d) Image formed will be complete when upper half of lens is blocked.
56.A short linear object of length b lies along the axis of a concave mirror of focal length f at a distance u from the pole of the mirror. The size of the image is approximately equal to [1988-2 marks]
57.A beam of light consisting of red, green and blue colours is incident on a right angled prism, as shown in figure. The refractive indices of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively. The prism will [1989-2 marks]
a)separate part of the red colour from the green and blue colours
b)separate part of the blue colour from the red and green colours
c)separate all the three colours from one another
d)not separate even partially any colour from the other two colours.
58.An astronomical telescope has an angular magnification of magnitude 5 for distant objects. The separation between the objective and the eyepiece is 36 cm and the final image is formed at infinity. The focal length f0 of the objective and the focal length fe of the eyepiece are
a)f0 = 45 cm and fe = -9 cm [1989-2 marks]
b)fo = 50 cm and fe = 10 cm
c)fo = 7.2 cm and fe = 5 cm
d)f0 = 30 cm and fe = 6 cm
59.A thin prism P1, with angle 4 ° and made from glass of refractive index 1.54 is combined with another thin prism P2 made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of the prism P2 is [1990-2 marks]
a) 5.33 ° b) 4 ° c) 3 ° d) 2.6 °
60.A planet is observed by an astronomical refracting telescope having an objective of focal length 16m and an eyepiece of focal length 2cm. [1992-2 marks]
a)The distance between the objective and the eyepiece is 16.02m
b)The angular magnification of the planet is -800
c)The image of the planet is inverted
d)The objective is larger than the eyepiece.
Ans.(c) A parallel beam of rays coming from the left is incident on the first lens of focal length fr The lens forms the image (It) at its focus. The image (Ij) serves as virtual object for second lens. The second lens forms the final image I at distance v2 from the second lens. I is the focal point of the lens system.
(i) Let x denote the distance of I from O.
62.A diminished image of an object is to be obtained on a screen 1.0 m from it. This can be achieved by appropriately placing [1995-2 marks]
a)a concave mirror of suitable focal length
b)a convex mirror of suitable focal length
c)a convex lens of focal length less than 0.25m
d)a concave lens of suitable focal length
Ans.(a), (c) An image obtained on screen is a real image. Convex mirror and concave lens do not form real image of an object.Options (b) and (d) do not hold good.Options (a) and (c) hold good. They are correct. For concave mirror, the object should be beyond C to form a real diminished image between F and C of mirror.
63.Which of the following form(s) a virtual & erect image for all positions of the object?[1996-2 marks]
a) Convex lens b) Concave lens
c) Convex mirror d) Concave mirror.
Ans.(b),(c) Concave lens and convex mirror are diverging in nature. For all positions of objects, they form virtual and erect image.
64.A real image of a distant object is formed by a plano-convex lens on its principal axis. Spherical aberration [1998-2 marks]
b)is smaller if the curved surface of the lens faces the object
c)is smaller if the plane surface of the lens faces the object
d)is the same whichever side of the lens faces the object
Ans.(b) Spherical aberration is smaller if the curved surface of the lens faces the object. The total deviation is shared between the curved and the plane surfaces.
65.A ray of light travelling in a transparent medium falls on a surface separating the medium from air at an angle of incidence 45 °. The ray undergoes total internal reflection. If M is the refractive index of the medium with respect to air, select the possible value(s) of p from the following [1998-2 marks]
a) 1.3 b) 1.4 c) 1.5 d) 1.6
66.A parallel monochromatic beam of light is incident normally on narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of the slit is [1998-2 marks]
67.A concave mirror is placed on a horizontal table, with its axis directed vertically upwards. Let O be the pole of the mirror & C its centre of curvature. A point object is placed at C. It has a real image, also located at C. If the mirror is now filled with water, the image will be: [1998-2 marks]
68.A spherical surface of radius of curvature R separates air (refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the siuface at a point O and PO = OQ . The distance PO is equal to [1998-2 marks]
a) 5R b) 3R c) 2R d) 1.5R
70.A student performed the experiment of determination of focal length of a concave mirror by u – v method using an optical bench of lengh 1.5 meter. The focal length of the mirror used is 24 cm. The maximum error in the location of the image can be 0.2 cm. The 5 sets of (u,v) values recorded by the student (in cm) are :(42,56), (48,48), (60,40), (66,33), (78,39).The data set(s) that cannot come from experiment and is (are) incorrectly recorded, is (are)
a)(42,56) b) (48,48) c) 66,33) d) 78,39)
Assertion & Reason Type
Instructions The following question contains
statement-I (assertion) and statement -2 (reason). Of these statements, mark correct choice if
a)Statements-1 and 2 are true and statement-2 is a correct explanation for statement-1
b)Statements-1 and 2 are true and statement-2 is not a correct explanation for statement-1
c)Statement-1 is true, statement-2 is flase
d)Statement-1 is false, statement-2 is true
72.Statement-1 : The formula connecting u. v and f for a spherical mirror is valid only for mirrors whose sizes are very small compared to their radii of curvature.
Statement-2 : Laws of reflection are strictly valid for plane surfaces, but not for large spherical surfaces. [2007-3 marks]
Comprehension based question type
Read the passage given below and answer the questions that follow
Paragraph-1: The figure shows a surface XY separating two transparent media, medium-1 and medium-2. The lines ab and cd represent wavefronts of a light wave travelling in medium- 1 and incident on XY. The lines ef and gh represent wavefronts of the light wave in medium-2 after refraction.
73.Light travels as a [2007-4 marks]
a)parallel beam in each medium
b)convergent beam in each medium
c)divergent beam in each medium
d)divergent beam in one medium and convergent beam in the other medium.
75.Speed of light is [2007-4 marks]
a)the same in medium-1 and medium-2
b)larger in medium-1 than in medium-2
c)larger in medium-2 than in medium-1
d)different at b and d
Ans.(b) The ray diagram suggests that on entering medium- 2, the ray bends towards normal, medium-2 is denser than medium-1.
76.A simple telescope used to view distant objects has eyepiece and objective lenses of focal lengths fe and f0 respectively. Then [2006-6 m]
77.An optical component and an object S placed along its optic axis are given in Column I. The distance between the object and the component can be varied. The properties of images are given in Column II. Match all the properties of images from Column II with the appropriate components given in Column I.
Subjective / Numerical integer type
Ans.A->p,s; B ->q;C->t;Dâ€” »r,s,t
80.A ray of light is incident at angle of 60 ° on one face of a prism which has an angle of 30 °. The ray emerging out of the prism makes an angle of 30 ° with the incident ray. Show that the emergent ray is perpendicular to the face through which it emerges and calculate the refractive index of the material of the lens. 
Ans.(c) The formula is derived under paraxial approximation, only those rays are considered which make very small angle with the principal axis. This requires a small aperture.
Statement-1 is true. Statement-2 is false, the laws of reflection are valid whenever the light is reflected. Nature of surface does not matter
81.A pin is placed 10 cm in front of a convex lens of focal length 20cm and made of a material of refractive index 1.5. The surface of the lens farther away from the pin is silvered and has a radius of curvature of 22 cm. Determine the position of the final image. Is the image real or virtual? 
85.An object is placed 21 cm in front of a concave mirror of radius curvature 10 cm. A glass slab of thickness 3 cm and refractive index 1.5 is placed close to the mirror in the space between the object and the mirror. Find the position of the final image formed. The distance of the nearer surface of the slab from mirror to be 1 cm. 
86.A telescope has an objective of focal length 50 cm and an eyepiece of focal length 5 cm. The least distance of distinct vision is 25 cm. The telescope is focussed for distinct vision on a scale 200 cm away from the objective. Calculate (a) the separation between the objective and the eyepiece and (b) the magnification produced 
87.The convex surface of a thin concavo-convex lens of glass of refractive index 1.5 has a radius of curvature 20 cm. The concave surface has a radius of curvature 60 cm. The convex side is slivered and placed on a horizontal surface. [1981-6 marks]
i)where should a pin be placed on the optic axis such that its image is formed at the same place?
ii)If the concave part is filled with water of refractive index 4/3, find the distance through whcih the pin should be moved so that the image of the pin again coincides with the pin.
88.Screen S is illuminated by two point sources A and B. Another source C sends a parallel beam of light towards point P on the screen (see figure). Line AP is normal to the screen and the lines AP, BP and CP are in one plane. The distance AP, BP and CP are 3m, 1.5 m & 1.5m respectively. The radiant powers of sources A and B are 90 watt and 180 watt respectively. The beam from C is of intensity 20 watt/m2. Calculate the intensity at P on the screen. [1982-5 marks]
Ans.Whenever any surface of a convex or plano-convex or concave convex lens is silvered, it behaves like
89.In Young’s double slit experiment using monochromatic light, the fringe pattern shifts by a certain distance on the screen, when a mica sheet of refractive index 1.6 and thickness 1.964 micron is introduced in the path of one of the interfering waves. The mica sheet is then removed and the distance between the slits and the screen is doubled. It is found that the distance between successive maxima (or minima) now is the same as the observed fringe shift upon the introduction of the mica sheet. Calculate the wavelength of the monochromatic light used in the experiment [1983-6 marks]
90.A piano convex lens has a thickness of 4 cm. When placed on a horizontal table, with the curved surface in contact with it, the apparent depth of the bottom most point of the lens is found to be 3 cm. If the lens is inverted such that the plane face is in contact with the table, the apparent depth of the centre of the palne face is found to be (25/8) cm. Find the focal length of the lens.
91.A beam of light consisting of two wavelengths, 6500 A and 5200 A, is used to obtain interference fringes in Young’s double slit experiment :
i)Find the distance of the third bright fringe on the screen from the central maximum for wavelength 6500 A
ii)What is the least distance from the central maximum where the bright fringes due to both the wavelengths coincide?
The distance between the slits is 2 mm and the distance between the plane of the slits and the screen is 120 cm. [1985-6 marks]