Reflection and Refraction of Light, Assignments of Physics

Download Reflection and Refraction of Light and more Assignments Physics in PDF only on Docsity! 9.2 Reflection of Light by Spherical Mirrors (5 marks) 1. Define the term ‘focal length of a mirror’. With the help of a ray diagram, obtain the relation between its focal length and radius of curvature. (2020) EEG 6 mark) 2. When an object is placed between f and 2f of a concave mirror, would the image formed be (i) real or virtual and (ii) diminished or magnified? (Delhi 2015C)(U) EEG (2 marks) _ 3. An object is kept 20 cm in front of a concave mirror of radius of curvature 60 cm. Find the nature and position of the image formed. (2020) An object is kept in front of a concave mirror of focal fength 15 cm. The image formed is real and three times the size of the object. Calculate the distance of the object from the mirror. (Al 2019) 5. Use the mirror equation to show. that-an-object placed between fand 2f of aconcave mirror produces areal image beyond 2f. (Delhi 2015) HEME (3 marks) 6. (a) Calculate the distance of an objects of ‘height ACL Mee CBSE Board Questions a i ’ r a a =a FEM (3 marks) h from a concave mirror of radius of curvature » 20 cm, so as to obtain a real image of : magnification 2. Find the location of image also. : (b) Using mirror formula, explain why does a convex : mirror always produce a virtual image. (Dethi 2016) (Rp) | 7. (a) A mobile phone lies along the principal axis of a ° concave mirror. Show, with the help of a suitable diagram, the formation of its image. Explain why magnification is not uniform. (b) Suppose the lower half of the concave mirror's : reflecting surface is covered with an opaque material. What effect this will have on the image of the object? Explain. EEEW (5 marks) _ 8. An object is placed in front of a concave mirror. Itis is observed that a virtual image is formed. Draw the (Delhi 2014) (Ap) | ray diagram to show the image formation and hence derive the mirror equation 11,1. (975, 2020) f uy (a) Draw a ray diagram to show image formation when the concave mirror produces a real, inverted and magnified image of the object. (b) Obtain the mirror formula and write the expression for the linear magnification (4/5, 2018) (Kn) 9.3 Refraction 10. Monachromatic light of wavelength 589 nm is incident from air on a water surface. If 1 for water is 1.33, find the wavelength, frequency and speed of the refracted light. (2/3, Al 2017) (Kp) 9.4 Total Internal Reflection Rey oho Here, question 11 wy to (v) is acase se study base question of 5 marks. 11. Aray of light travels from a denser to a rarer medium. After refraction, it bends away from the normal, When we keep increasing the angle of incidence, the angle of refraction also increases till the refracted Tay grazes along the interference of two media. The angle of incidence for which it happens is called critical angle. If the angle of incidence is.increased further the ray will not emerge and it will be reflected back in the denser medium. This phenomenon is called total internal reflection of light. (i) A ray of light travels from a medium into water at an angle of incidence of 18° The refractive index of the medium is more than that of water and the critical angle for the interface between the two media is 20° Which one of the following figures best represents the correct path of the ray of light? (a) (b) () (d) 18° as (ii) A point source of light is placed at the bott of a tank filled with water, of refractive index }. Ce CamsSc  a depth d. The area of the surface of water through which light from the source can emerge. is. ? 2 o =< os an?) (n ha 2nd? ) = (a) Va yn?-d We (iii) For which of the following media, with respect to air, the value of critical angle is maximum? fa) Crown glass (b) Flint glass (©) Water {d) Diamond {iv) The critical angle for a pair of two media A and B of refractive indices 2.0 and 1.0 respectively is: (a) 0° {b) 30° te) 45" (ad) 60° (v) The critical angle of pair of a medium and air is 30° The speed of light in the medium is: (a) 1 10%ms"? (b) 1.510% ms! () 2.2*10%ms! {d) 2.8 10%ms? (Term |] 2021-22) BEGET (2 marks) 12. How does the refractive index of a transparent medium depend on the wavelength of incident light used? Velocity of light in glass is 2 x 10° m/s and in air is 3 x 10° m/s. If the ray of light passes from glass to air, calculate the value of critical angle. (Foreign 2015)(Ap) 13. {a) Write the necessary conditions fcr the phenomenon of total internal reflection to occur. (b) Write the relation between the refractive index and critical angle for a given pair of optical media. {Delhi 2013) En (3 marks) 14. Define the term ‘critical angle’ for a pair of media. A point source of monochromatic light ‘S’ is kept at the centre of the bottom of a cylinder of radius 15.0 cm. The cylinder contains water (refractive index 4/3) to a height of 7.0 cm. Draw the ray diagram and calculate the area of water surface through which the light emerges in air. (Delhi 2013¢) small bulb (assumed to be a point source) is placed At the bottom of a tank containing water to a depth of 80 cm. Find out the area of the surface of water through which light from the bulb can emerge. Take the value of the refractive index of water to be 4/3. (Delhi 2013C) a (5 marks) (1) Under what conditions is the phenomenon of total internal reflection of light observed ? Obtain the oh relation between the eritical angle of incidence ang the refractive index of the medium: (3/5, Dethi 2019) (Ap) 9.5 Refraction at Spherical Surfaces and by Lenses BRE 11 maria 17. A ray of light falls on a transparent sphere with centre C as shown in the figure. The ray emerges from the sphere parallel to the line AB. Find the angle of refraction at A if refractive index of the material of the sphereis /3. Here, question 18 (i) to (v) is a case study base question of 5 marks. 18. Two transparent media of refractive indices n, anda, are separated by a spherical transparent surface. The rays o/ light incident on the surface.get refracted into the medium on the other side. The laws of refraction are valid at each point of the spherical surface. A lens is a transparent optical medium bounded by two surfaces, at least one of which should be spherical. The focal length of a lens is determined by the radii of curvature (R, and R;) of its two surfaces and the refractive index(n) of the medium of the lens with respect to the surrounding medium. Depending on R, and R2 a lens behaves as a diverging or a converging lens. The ability of a lens to diverge or converge a beam of light incident on it define its power, (i) An object is placed at the point B as shown in the figure. The object distance {u) and the image distance (v) are related as Pa, Cc 8 (ny >) CB cansean