Practice Test


1) A concave mirror has a focal length of 2 meter in vacuum. What would be its focal length when used in a medium of refractive index 2.759 ?


2) A clock hung on a wall has marks instead of numerals in its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicates the time 4.20. Then the time on the clock is


3) In a plane mirror, an object is 0.5 m in front of the mirror. The distance between object and image is


4) An object 0.5 m tall is in front of a plane mirror at a distance of 0.2 m. The size of the image formed is


5) When a convergent beam of light is incident on a plane mirror, the image formed is


6) A plane mirror reflects a pencil of light to form a real image. Then the pencil of light incident on the mirror is


7) A light ray incident normally on a plane mirror suffers a deviation of


8) A candle is placed before a thick plane mirror. When looked obliquely in the mirror a number of images are seen from the surfaces of the plane mirror. Then


9) A boy stands in front of a plane mirror with his hand at 0.3 m from the mirror. In order to see the image of his hand clearly, he must focus his eye at a distance of


10) The power of a plane mirror is


11) How many images of himself does an observer see if two adjacent walls of rectangular room are mirror surfaced ?


12) A man 2 m tall stands 5 m in front of a large vertical plane mirror. Then the angle subtended at his eye by his image in the plane mirror is


13) A man 180 cm high stands in front of a plane mirror. His eyes are at a height of 170 cm from the floor. Then the minimum length of the plane mirror for him to see his full length image is


14) It is desired to photograph the image of an object placed at a distance of 3m from a plane mirror. The camera which is at a distance of 4.5 m from the mirror should be focused for a distance of


15) A person standing in the centre of a room, 12 m high looks into a plane mirror fixed on the wall. Then the minimum length of the plane mirror for him to see the full length image of the wall behind him, is equal to


16) An object is placed between two parallel plane mirrors,. The number of images formed is


17) The images of clouds and trees in water are always less bright than in reality


18) The image of an object formed by a plane mirror is


19) An object is placed between two plane mirrors inclined at an angle to each other. If the number of images formed is 7 then the angle of inclination is


20) Which of the following letters do not suffer lateral inversion


21) Two mirrors are placed perpendicular to each other. A ray strikes the first mirror and after reflection from the first mirror it falls on the second mirror. The ray after reflection from the second mirror will emerge


22) If you want to see your full image, then minimum size of the mirror :


23) A number of images of a candle flame can be seen in a thick mirror. The brightest image is


24) Statement 1 : When an object is placed between two plane parallel mirrors, then all found are of equal intensity.
Statement 2 : In case of plane parallel mirrors, infinite images are formed.


25) Statement 1 : A ray incident along normal to the mirror retraces its path.
Statement 2 : In reflection, angle of incidence is always equal to angle of reflection.


26) The angle at which the ray is incident on the second mirror


27) The angle at which the ray is incident on the first mirror after being reflected from the second mirror is


28) The angle of deviation between incidence ray and first reflected ray is


29) The glancing angle with the first mirror is


30) The glancing angle with the second mirror is


31) The total deflection of the incident ray after two reflection is


32) A cut diamond sparkles because of its


33) A diver in a swimming pool wants to signal his distress to a person lying on the edge of the pool by flashing his water proof flash light


34) Finger prints on a piece of paper may be detected by sprinkling fluorescent powder on the paper and then looking it into


35) Critical angle of light passing from glass to air is minimum for


36) Total internal reflection of light is possible when light enters from


37) Critical angle is that angle of incidence in the denser medium for which the angle of refraction in rarer medium is


38) The critical angle for diamond (refractive index = 2) is


39) The reason for shining of air bubble in water is


40) 'Mirage' is a phenomenon due to


41) When a ray of light emerges from a block of glass, the critical angle is


42) The phenomenon utilised in an optical fibre is


43) The refractive index of water is 4/3 and that of glass is 5/3. What will be the critical angle for the ray of light entering water from the glass


44) Total internal reflection is possible when light rays travel


45) The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected, is


46) A ray of light propagates from glass (refractive index = 3/2) to water (refractive index = 4/3). The value of the critical angle


47) Relation between critical angles of water and glass is


48) The refractive index of water is 1.33. The direction in which a man under water should look to see the setting sun is


49) Optical fibres are related with


50) Brilliance of diamond is due to


51) Light wave enters from medium 1 to medium 2. Its velocity in 2nd medium is double from 1st . For total internal reflection the angle of incidence must be greater than


52) Consider telecommunication through optical fibres. Which of the following statements is not true


53) An endoscope is employed by a physician to view the internal parts of a body organ. It is based on the principle of


54) The phenomena of total internal reflection is seen when angle of incidence is


55) A point source of light is placed 4 m below the surface of water of refractive index 5 / 3. The minimum diameter of a disc which should be placed over the source on the surface of water to cut-off all light coming out of water is


56) What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other


57) A plane mirror is approaching you at a speed of 10 cm/sec. You can see your image in it. At what speed will your image approach you


58) A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the


59) A man is 180 cm tall and his eyes are10 cm below the top of his head. In order to see his entire height right from toe to head, he uses a plane mirror kept at a distance of 1 m from him. The minimum length of the plane mirror required is


60) A person is in a room whose ceiling and two adjacent walls are mirrors. How many images are formed


61) A ray of light is incidenting normally on a plane mirror. The angle of reflection will be


62) When light wave suffers reflection at the interface from air to glass, the change in phase of the reflected wave is equal to


63) A ray is reflected in turn by three plain mirrors mutually at right angles to each other. The angle between the incident and the reflected rays is


64) Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand


65) A plane mirror produces a magnification of


66) A watch shows time as 3 : 25 when seen through a mirror, time appeared will be


67) If an observer is walking away from the plane mirror with 6 m/sec. Then the velocity of the image with respect to observer will be


68) A man runs towards mirror at a speed of 15 m/s. What is the speed of his image


69) A small object is placed 10 cm in-front of a plane mirror. If you stand behind the object 30 cm from the mirror and look at its image, the distance focused for your eye will be


70) An object is at a distance of 0.5 m in front of a plane mirror. Distance between the object and image is


71) A man runs towards a mirror at a speed 15 m/s The speed of the image relative to the man is


72) The light reflected by a plane mirror may form a real image


73) A man of length h requires a mirror, to see his own complete image of length at least equal to


74) A man having height 6 m. He observes image of 2 m height erect, then mirror used is


75) Focal length of a plane mirror is