Reflection by Plane & Spherical Mirrors — Practice Questions

Free NEET Physics multiple-choice questions on Reflection by Plane & Spherical Mirrors. Attempt each question and reveal the answer with a full explanation.

A concave mirror of focal length f is immersed in water ( n = 4/3 ). The focal length of the mirror in water will be: f 4f/3 3f/4 7f/3 An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of Large focal length and large diameter Large focal length and small diameter Small focal length and large diameter Small focal length and small diameter In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction? 90 180 0 Equal to angle of incidence A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since A large aperture contributes to the quality and visibility of the images. A large area of the objective ensures better light gathering power. A large aperture provides a better resolution. All of the above A convex lens 'A' of focal length 20 cm and a concave lens 'B' of focal length 5 cm are kept along the same axis with a distance ' d ' between them. If a parallel beam of light falling on 'A' leaves 'B' as a parallel beam, then the distance ' d ' in cm will be 15 50 30 25 A biconvex lens has radii of curvature, 20 cm each. If the refractive index of the material of the lens is 1.5, the power of the lens is +20 D +5 D Infinity +2 D Two transparent media A and B are separated by a plane boundary. The speed of light in those media are 1.5 10 8 m/s and 2.0 10 8 m/s , respectively. The critical angle for a ray of light for these two media is -1 (0.750) -1 (0.500) -1 (0.750) -1 (0.500) Two thin lenses are of same focal lengths ( f ), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be Zero f 4 f 2 Infinite A small telescope has an objective of focal length 140 cm and an eye piece of focal length 5.0 cm. The magnifying power of telescope for viewing a distant object is: 34 28 17 32 In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to the power ( p ) and magnification ( m ) for each lens will be, respectively p 4 and m 4 4p and 4m p 4 and 4m 4p and m 4 A microscope has an objective of focal length 2 cm, eyepiece of focal length 4 cm and the tube length of 40 cm. If the distance of distinct vision of eye is 25 cm, the magnification in the microscope is 250 100 125 150 Two plane mirrors are inclined at an angle of 60 . The number of images of a point object placed symmetrically between them is: 5 6 7 Infinite In a concave lens, a ray of light emanating from the object parallel to the principal axis of the lens after refraction: passes through the second principal focus. appears to diverge from the first principal focus. passes through 2F , which is the radius of curvature of the lens. emerges parallel to the principal axis. A plane wavefront is incident on a concave mirror. The reflected wavefront will be: Converging spherical Diverging spherical Plane Cylindrical An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm . The magnification produced is: 0.6 0.4 1.5 2.5 A ray of light is incident on a plane mirror at an angle of 30 with the mirror surface. The angle of deviation is: 120 60 30 90 Two plane mirrors are inclined at an angle of 72 . The number of images formed for an object placed asymmetrically between them is: 5 4 6 Infinite A concave mirror produces a real image three times the size of the object. If the focal length of the mirror is 15 cm , the object distance is: 20 cm 10 cm 30 cm 60 cm A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid? 2.4 10 8 m/s 3.0 10 8 m/s 1.2 10 8 m/s 1.8 10 8 m/s A plano-convex lens fits exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If lenses are made of different materials of refractive indices 1 and 2 and R is the radius of curvature of the curved surface of the lenses, then the focal length of the combination is R 2( 1 + 2) R 2( 1 - 2) R ( 1 - 2) 2R ( 2 - 1) The angle of a prism is ‘A’. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index , of the prism is :- 2 A 2 A 1 2 A A The angle of incidence for a ray of light at a refracting surface of a prism is 45 . The angle of prism is 60 . If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are : 45 , 1 2 30 , 2 45 , 2 30 , 1 2 In the case of a convex mirror, for any position of the real object, the image is always: Virtual, erect and diminished Real, inverted and magnified Virtual, erect and magnified Real, inverted and diminished A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively. To view an object 200 cm away from the objective, the lenses must be separated by a distance :- 37.3 cm 46.0 cm 50.0 cm 54.0 cm Match the corresponding entries of column-1 with column-2 (Where m is the magnification produced by the mirror) :- A b and c, B b and c, C b and d, D a and d. A a and c, B a and d, C a and b, D c and d A a and d, B b and c, C b and d, D b and c A c and d, B b and d, C b and c, D a and d A person has near point at 60 cm. The focal length of spectacles lenses to read at 22 cm having glasses separated 2 cm from the eyes, is : 40 cm 10 cm 20 cm 30 cm A light beam is incident on a denser medium whose refractive index is 1.414 at an angle of incidence 45 . Find the ratio of width of refracted beam in a medium to the width of the incident beam in air. 3 : 2 1: 2 2 :1 2 : 3 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 prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is 30 45 60 Zero An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be 30 cm towards the mirror 36 cm away from the mirror 30 cm away from the mirror 36 cm towards the mirror Two similar thin equi-convex lenses, of focal length f each, are kept coaxially in contact with each other such that the focal length of the combination is F 1 . When the space between the two lenses is filled with glycerine (which has the same refractive index ( = 1.5) as that of glass) then the equivalent focal length is F 2 . The ratio F 1 : F 2 will be : 3 : 4 2 : 1 1 : 2 2 : 3 Pick the wrong answer in the context with rainbow. Rainbow is a combined effect of dispersion refraction and reflection of sunlight When the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed The order of colours is reversed in the secondary rainbow An observer can see a rainbow when his front is towards the sun A ray is incident at an angle of incidence i on one surface of a small angle prism (with angle of prism A) and emerges normally from the opposite surface. If the refractive index of the material of the prism is , then the angle of incidence is nearly equal to : 2A A A 2 A 2 The Brewsters angle i b for an interface should be 30 < i b < 45 45 < i b < 90 i b = 90 0 < i b < 30 A microscope is focused on a mark on a piece of paper and then a slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again:- 1 cm upward 4.5 cm downward 1 cm downward 2 cm upward Find the value of the angle of emergence from the prism. Refractive index of the glass is 3 . 30° 45° 90° 60° A point object is placed at a distance of 60 cm from a convex lens of focal length 30 cm. If a plane mirror were put perpendicular to the principal axis of the lens and at a distance of 40 cm from it, the final image would be formed at a distance of 30 cm from the lens, it would be a real image 30 cm from the plane mirror, it would be a virtual image 20 cm from the plane mirror, it would be a virtual image 20 cm from the lens, it would be a real image A light ray falls on a glass surface of refractive index 3 , at an angle 60 . The angle between the refracted and reflected rays would be 60 90 120 30 Light travels a distance x in time t 1 in air and 10x in time t 2 in another denser medium. What is the critical angle for this medium? -1 ( t 2 t 1 ) -1 ( 10t 2 t 1 ) -1 ( t 1 10t 2 ) -1 ( 10t 1 t 2 ) A light ray enters through a right angled prism at point P with the angle of incidence 30 as shown in figure. It travels through the prism parallel to its base BC and emerges along the face AC . The refractive index of the prism is: 5 4 5 2 3 4 3 2 A ray of monochromatic light is passing through an equilateral prism (ABC) as shown in the figure. The refracted ray (QR) is parallel to its base (BC) and the angle of incidence (i) is 50 . Then the angle of deviation ( ) is: 45 55 35 40 An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm . If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be: 36 cm away from mirror 30 cm away from mirror 30 cm towards mirror 36 cm towards mirror A linear object of length 10 cm is placed along the principal axis of a concave mirror of focal length 20 cm such that its end closer to the mirror is 30 cm away from the mirror. The length of the image is: 20 cm 10 cm 15 cm 25 cm An object moves at a constant speed v towards a convex mirror of focal length f along the principal axis. When the object is at a distance f from the mirror, the speed of the image is: v/4 v/2 v v/9 In the figure shown here, what is the equivalent focal length of the combination of lenses (Assume that all layers are thin)? 40 cm -40 cm -100 cm -50 cm A convex lens and a concave lens, each having same focal length of 25 cm, are put in contact to form a combination of lenses. The power in dipoters of the combination is:- 25 50 Infinite Zero The frequency of a light wave in a material is 2 10 14 Hz and wavelength is 5000 Å. The refractive index of material will be 1.50 3.00 1.33 1.40 For a normal eye, the cornea of eye provides a converging power of 40 D and the least converging power of the eye lens behind the cornea is 20 D. Using this information, the distance between the retina and the cornea - eye lens can be estimated to be 5 cm 2.5 cm 1.67 cm 1.5 cm If the focal length of objective lens is increased then magnifying power of :- microscope will increase but that of telescope decrease. microscope and telescope both will increase. microscope and telescope both will decrease microscope will decrease but that of telescope increase. If the angle of a prism is 60 and angle of minimum deviation is 40 , then the angle of refraction will be 4 30 20 3