Refraction at Plane Surfaces & TIR — Practice Questions

Free NEET Physics multiple-choice questions on Refraction at Plane Surfaces & TIR. Attempt each question and reveal the answer with a full explanation.

A beam of light composed of red and violet colors is incident on a glass slab, making a non-zero angle with the normal. After passing through the slab, the red and violet beams come out from the opposite face: Parallel to each other but displaced laterally Converging towards each other Diverging from each other At an angle of 90 o to each other A ray of light is incident on a glass plate at an angle of 60 . If the reflected and refracted rays are mutually perpendicular, the refractive index of glass is: 3 3/2 4/3 2 The speed of light in vacuum ( c ) is related to the permeability ( 0 ) and permittivity ( 0 ) of free space by: c = 1 0 0 c = 0 0 c = 0 0 c = 1 0 0 If the critical angle for total internal reflection from a medium to vacuum is 30 , the velocity of light in the medium is: 1.5 10 8 m/s 3 10 8 m/s 2 10 8 m/s 6 10 8 m/s A ray of light falls on a transparent glass slab of refractive index 1.62 . If the reflected ray and the refracted ray are perpendicular, the angle of incidence is: -1 (1.62) -1 (1.62) -1 (1.62) 45 The dispersive power of the material of a prism depends on: The nature of the material The angle of the prism The angle of incidence The size of the prism When unpolarized light is incident on a glass surface at an angle of 57 , the reflected light is completely plane polarized. The angle of refraction is: 33 57 90 0 When a light wave travels from air to glass, which of the following remains constant? Frequency Wavelength Velocity Amplitude The angular resolution of a 10 cm diameter telescope at a wavelength of 5000 is of the order of - 10 -4 rad 10 -6 rad 10 6 rad 10 -2 rad A beam of light of = 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 first dark fringes on either side of the central bright fringe is :- 1.2 cm 1.2 mm 2.4 cm 2.4 mm A parallel beam of light of wavelength is incident normally on a single slit of width d. Diffraction bands are obtained on a screen placed at a distance D from the slit. The second dark band from the central bright band will be at a distance given by : 2 D d d D D 2d 2 d D A ray of light is incident at the Brewster's angle B on the surface of a transparent medium of refractive index n . If the angle of refraction is r , then: B + r = 90 o B = r B + r = 180 o B + r = 45 o In Young’s double slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes : half four times one-fourth double In a Young’s double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is 8 9 12 6 An unpolarised light beam strikes a glass surface at Brewster’s angle. Then The reflected light will be partially polarised. The refracted light will be completely polarised. Both the reflected and refracted light will be completely polarised. The reflected light will be completely polarised but the refracted light will be partially polarised. If the monochromatic source in Young’s double slit experiment is replaced by white light, then Interference pattern will disappear There will be a central dark fringe surrounded by a few coloured fringes There will be a central bright white fringe surrounded by a few coloured fringes All bright fringes will be of equal width An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster’s angle. Then Transmitted light is completely polarized with angle of refraction close to 30 Reflected light is completely polarized and the angle of reflection is close to 60 Reflected light is partially polarized and the angle of reflection is close to 30 Both reflected and transmitted light are perfectly polarized with angles of reflection and refraction close to 60 and 30 , respectively In interference and diffraction, the light energy is redistributed. If it reduces in one region, producing a dark fringe, it increases in another region, producing a bright fringe. A. As there is no gain or loss of energy, these phenomena are consistent with the principle of conservation of energy. B. Diffraction and interference are characteristics exhibited only by light waves. Choose the correct answer from the options given below: A is false, but B is true A is true, but B is false A is true and B is also true Both A and B are false A ray of light is incident at an angle of 45 on one face of a prism of angle 60 . The ray undergoes minimum deviation. The refractive index of the material of the prism is: 2 3 1.5 1.33 The critical angle for a light ray going from medium A to medium B is . If the speed of light in medium A is v , then the speed of light in medium B is: v/ v v/ v A ray of light is incident at an angle i on a surface of a small angle prism (angle A ) and emerges normally from the opposite surface. If the refractive index of the material is , the angle of incidence i is nearly equal to: A A / A / 2 A / 2 The refractive index of glass is 1.5 and that of water is 1.33. The critical angle for a ray of light going from glass to water is: -1 (8/9) -1 (1/2) -1 (4/5) -1 (2/3) A ray of light is incident on an equilateral glass prism such that the angle of incidence is equal to the angle of emergence, and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is: 30 o 45 o 20 o 37.5 o A ray of light travels from an optically denser to rarer medium. The critical angle for the two media is C . The maximum possible deviation of the ray is: - 2C /2 - C - C 2C A thin prism of 6 angle having refractive index 1.5 is combined with another thin prism of refractive index 1.6 to produce dispersion without deviation. The angle of the second prism is: 5 6 4 7.2 The speed of light in media M 1 and M 2 are 1.5 10 8 m/s and 2.0 10 8 m/s respectively. A ray of light enters from medium M 1 to M 2 at an incidence angle i . If the ray suffers total internal reflection, the value of i is: Equal to or greater than sin -1 (3/4) Equal to or greater than sin -1 (2/3) Less than sin -1 (2/3) Less than sin -1 (3/4) A ray of light is incident on one face of a transparent slab of thickness 15 cm at an angle of 60 o . The refractive index of the slab is √ 3 . The lateral shift of the ray is: 5 √ 3 cm 5 cm 10 cm 15 √ 3 cm A ray of light is incident at angle i on one surface of a small angle prism A and emerges normally from the opposite surface. If the refractive index of prism is n , then the angle of incidence i is: nA A/n nA/2 A/2n A fish looking up through water ( n = 4/3 ) sees the outside world contained in a circular horizon. If the fish is at a depth of 7 cm , the radius of this circle is: 7/ √ 7 cm 7 √ 7 cm 3 √ 7 cm 4 √ 7 cm Which of the following is true for the formation of a secondary rainbow? Two internal reflections and two refractions One internal reflection and two refractions Two internal reflections and one refraction One internal reflection and one refraction A vessel is filled with three immiscible liquids of densities d 1, d 2, d 3 and thicknesses h 1, h 2, h 3 with refractive indices 1, 2, 3 . The apparent depth of the vessel when viewed from above is: h 1 1 + h 2 2 + h 3 3 1 h 1 + 2 h 2 + 3 h 3 h 1+h 2+h 3 1+ 2+ 3 1 h 1 + 2 h 2 + 3 h 3 A ray of light is incident on a transparent glass slab of refractive index 1.5. If the reflected and refracted rays are perpendicular, the angle of incidence is: -1 (1.5) -1 (1.5) -1 (1.5) 45 Light appears to travel in straight lines because its: Wavelength is very small Velocity is very large Frequency is very small It is not absorbed by atmosphere Which of the following is correct for a primary rainbow? It is formed by two refractions and one internal reflection It is formed by two refractions and two internal reflections Violet color is on the outer edge It is formed by scattering only A ray of light is incident normally on one face of a right-angled isosceles prism. If it undergoes total internal reflection at the hypotenuse, the minimum refractive index of the material must be: 2 1.5 3 2.0 In Young’s double slit experiment, the slits are 2 mm apart and are illuminated by photons of two wavelengths 1 = 12000 and 2 = 10000 . At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other? 8 mm 6 mm 4 mm 3 mm In the Young's double-slit experiment, the intensity of light at a point on the screen where the path difference is is K, ( being the wave length of light used). The intensity at a point where the path difference is /4 , will be :- K K/4 K/2 Zero In a diffraction pattern due to a single slit of width 'a', the first minimum is observed at an angle 30 when light of wavelength 5000 Å is incident on the slit. The first secondary maximum is observed at an angle of : -1 ( 1 4 ) -1 ( 2 3 ) -1 ( 1 2 ) -1 ( 3 4 ) The intensity at the maximum in a Young's double slit experiment is I 0 . Distance between two slits is d = 5 , where is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance D = 10 d ? I 0 I 0 4 3 4 I 0 I 0 2 Two coherent sources of intensity ratio interfere. The value of I -I I +I is : 1+ 2 1+ 1+ 2 1- 1+ Unpolarised light is incident from air on a plane surface of a material of refractive index ' '. At a particular angle of incidence 'i', it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation? i = -1 ( 1 ) Reflected light is polarised with its electric vector perpendicular to the plane of incidence Reflected light is polarised with its electric vector parallel to the plane of incidence i = -1 ( 1 ) In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength of the light used is 5896 and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20 . To increase the fringe angular width to 0.21 (with same and D) the separation d between the slits needs to be changed to 2.1 mm 1.9 mm 1.8 mm 1.7 mm In a double slit experiment, when light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed 1 m away, was found to be 0.2°. What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? ( water =4/3 ) 0.1° 0.266° 0.15° 0.05° Assume that light of wavelength 600 nm is coming from a star. The limit of resolution of telescope whose objective has a diameter of 2 m is : 1.83 10 -7 rad 7.32 10 -7 rad 6.00 10 -7 rad 3.66 10 -7 rad The refractive index of water is 1.33 . What will be the speed of light in water? 2.25 10 8 m/s 3 10 8 m/s 1.5 10 8 m/s 4 10 8 m/s For Young’s double slit experiment, two statements are given below: Statement I : If screen is moved away from the plane of slits, angular separation of the fringes remains constant. Statement II : If the monochromatic source is replaced by another monochromatic source of larger wavelength, the angular separation of fringes decreases. In the light of the above statements, choose the correct answer from the options given below: Both Statement I and Statement II are true. Both Statement I and Statement II are false. Statement I is true but Statement II is false. Statement I is false but Statement II is true. The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at 22.5 from the polarization axis of one of the polaroids, is ( I 0 is the intensity of polarised light after passing through the first polaroid): I 0 16 I 0 2 I 0 4 I 0 8 In Young’s double slit experiment, using monochromatic light of wavelength , the intensity of light at a point on the screen where the path difference is , is K units. The intensity of light at a point where the path difference is 3 will be K 2K K 2 K 4 A point source of light is placed at the bottom of a tank containing water ( n = 4/3 ) up to a depth of 80 cm . The area of the surface of water through which light from the source can emerge out is: 2.58 m 2 6.25 m 2 1.48 m 2 4.32 m 2 The refractive index of the material of a prism is 2 and the angle of the prism is 30 . One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is: 45 30 60 zero When a small amount of phosphorus is added to silicon, what happens to the refractive index of the material? It changes slightly due to change in electron density It remains exactly the same It becomes zero It becomes infinite A ray of light is incident on a prism of angle A at grazing incidence and emerges from the other face at grazing emergence. The refractive index of the prism is: (A/2) (A/2) (A/2) (A/2) A point source of light is placed at the center of the bottom of a cylinder of radius 3 cm and height 4 cm filled with water ( n=4/3 ). Will any light emerge from the vertical curved surface? Yes, from the upper part No, only from the top surface Yes, from the whole surface Light cannot travel in water A ray of light is incident at Brewster's angle p on a glass slab. If c is the speed of light in vacuum and v is the speed of light in the glass, then: v = c p v = c p v = c p v = c / p Consider three media P , Q and R with refractive indices 1 , 1.25 and 1.5 respectively. The medium Q having a thickness of 5 cm is placed in between extended media P and R as shown in the figure. An object O is placed at the centre of medium Q . If viewed from medium P near the normal direction, the apparent depth of O is h 1 . For similar observation from medium R , the apparent depth is h 2 . The value of |h 1-h 2| , in cm, is: 0 1 2 3 When a light wave of frequency and wavelength travels from air into a medium of refractive index n , the frequency and wavelength in the medium will be: , /n /n, /n , n /n, The ratio of the speed of light in vacuum to the speed of light in a medium is known as: Absolute refractive index Relative refractive index Optical density Polarizing angle In the phenomenon of Total Internal Reflection, when the angle of incidence is equal to the critical angle, the angle of refraction is: 90 0 180 45 The phenomenon used in optical fibers to transmit light signals is: Total Internal Reflection Diffraction Polarization Interference