CBSE Class 10 Physics Light Reflection and Refraction MCQs Set B

Question. When a convex lens made up of glass is immersed in water, its focal length    
(a) decreases
(b) does not change
(c) increases
(d) None of the above

Answer : C

Question. A 10 mm long awlpin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is  
(a) – 30 cm
(b) – 20 cm
(c) – 40 cm
(d) – 60 cm

Answer : B

Question. The linear magnification for a mirror is the ratio of the size of the image to the size of the object, and is denoted by m. Then, m is equal to (symbols have their usual meanings):  
(a) f/ f - u
(b) f - u/f
(c) f/ f + v
(d) f + v/f

Answer : A

Question. An inverted image can be seen in a convex mirror,    
(a) under no circumstances
(b) when the object is very far from the mirror
(c) when the object is at a distance equal to the radius of curvature of the mirror
(d) when the distance of the object from the mirror is equal to the focal length of the mirror

Answer : A

Question. When an objects is placed between two mirrors placed inclined to each at an angle 45° Number of images formed are     
(a) 3
(b) 5
(c) 7
(d) None of these

Answer : C

Question. Two plane inclined mirrors form 5 images by multiple reflection. The angle of inclination is  
(a) 90°
(b) 60°
(c) 45°
(d) 30°

Answer : B

Question. For an object at infinity, a concave mirror produces an image at its focus which is    
(a) enlarged
(b) virtual
(c) erect
(d) real and point sized

Answer : D

Question. Foam of soap always appears white as   
(a) it contains large hydrocarbon chains.
(b) it absorbs red portion of the visible light
(c) it reflects light of all wavelengths.
(d) it has one hydrophobic end, which is insoluble in water.

Answer : C

Question. A bright × (cross) mark is made on a sheet of white paper. Over the white paper a rectangular glass-slab of thickness 3 cm is placed. On looking through, the image of the mark appears above the mark. It is below the upper surface of the slab by (μglass = 1.5)  
(a) 2.5 cm
(b) 1.5 cm
(c) 2 cm
(d) 1.75 cm

Answer : C

Question. When viewed vertically a fish appears to be 4 meter below the surface of the lake. If the index of refraction of water is 1.33, then the true depth of the fish is  
(a) 5.32 metres
(b) 3.32 metres
(c) 4.32 metres
(d) 6.32 metres

Answer : A

Question. A diverging lens with magnitude of focal length 25 cm is placed at a distance of 15 cm from a converging lens of magnitude of focal length 20 cm. A beam of parallel light falls on the diverging lens. The final image formed is :   
(a) real and at a distance of 40 cm from the divergent lens
(b) real and at a distance of 6 cm from the convergent lens
(c) real and at a distance of 40 cm from convergent lens
(d) virtual and at a distance of 40 cm from convergent lens.

Answer : C

Question. The ratio of the sine of angle of incidence to the sine of angle of refraction is called   
(a) refractive index
(b) optical density
(c) relative density
(d) none of these

Answer : A

Question. A convex lens is put 10 cm from a light source and it makes a sharp image on a screen, kept 10 cm from the lens. Now a glass block (refractive index 1.5) of 1.5 cm thickness is placed in contact with the light source. To get the sharp image again, the screen is shifted by a distance d. Then d is:   
(a) 1.1 cm away from the lens
(b) 0
(c) 0.55 cm towards the lens
(d) 0.55 cm away from the lens

Answer : D

Question. In order to get a diminished virtual image, the object can be placed anywhere in front of a     
(a) concave mirror
(b) plane mirror
(c) convex mirror
(d) none of these

Answer : C

Question : If an incident ray passes through the focus, the reflected ray will
(a) pass through the pole
(b) be parallel to the principal axis
(c) retrace its path
(d) pass through the centre of curvature

Answer :  B

Question : In case of refraction, if the angle of incidence and the angle of refraction are 45 degrees and 30 degrees respectively, then the angle of deviation is
(a) 75 o
(b) 15o
(c) 7.5o
(d) 37.5o

Answer :  B

Question : Which of the following statements is true?
(a) A convex lens has 4 dioptre power having a focal length 0.25 m
(b) A convex lens has –4 dioptre power having a focal length 0.25 m
(c) A concave lens has 4 dioptre power having a focal length 0.25 m
(d) A concave lens has –4 dioptre power having a focal length 0.25 m

Answer :  A

Question : Under which of the following conditions a concave mirror can form an image larger than the actual object?
(a) When the object is kept at a distance equal to its radius of curvature
(b) When object is kept at a distance less than its focal length
(c) When object is placed between the focus and centre of curvature
(d) When object is kept at a distance greater than its radius of curvature

Answer :  C

Question : A concave mirror forms a real and enlarged image of an object if the object is placed at/between
(a) 2F
(b) F
(c) F and C
(d)F and P

Answer :  C

Question : Focal length of a plane mirror is
(a) zero
(b)infinity
(c) double of its aperture
(d)half of its aperture

Answer :  A

Question : Between red and violet, which color has more frequency? 
(a) Red has more frequency than violet
(b) Violet has more frequency than red
(c) Red and violet has the same frequency
(d) Can not say

Answer :  B

Question : An object at a distance of + 15 cm is slowly moved towards the pole of a convex mirror. The image will get
(a) shortened and real
(b) enlarged and real
(c) enlarge and virtual
(d) diminished and virtual

Answer :  D

Question : Pradeep Appeared In Class Test But He Confused To Know The Correct Statement. Would You Help Him To Know That?
(a) According to the first law of refraction of light, the incident ray, the refracted ray and the normal at the point of incidence, all lie in the same plane.
(b) According to Snell’s law of refraction of light, the ratio of sine of angle of incidence to the sine of angle of refraction is constant for a given pair of media.
(c) The refractive index of a medium gives an indication of the light bending ability of that medium.
(d) All the above.

Answer :  D

Question : In case of refraction, when the light passes from rarer to a denser medium, if the angle of incident is 65o and angle of refraction is 25o, then the deviation of angle would be-
(a) 65o
(b) 25o
(c) 40o
(d) 30o

Answer :  C

Question : In torches, search lights and headlights of vehicles the bulb is placed
(a) between the pole and the focus of the reflector
(b) very near to the focus of the reflector
(c) between the focus and centre of curvature of the reflector
(d) at the centre of curvature of the reflector

Answer :  B

Question : An object at a distance of 30 cm from a concave mirror gets its image at the same point. The focal length of the mirror is
(a) – 30 cm
(b) 30 cm
(c) – 15 cm
(d) +15 cm

Answer :  C

Question : To obtain parallel ray from a point light source we use
(a) both convex lens and concave mirror
(b) both convex lens and convex mirror
(c) both concave lens and concave mirror
(d) both concave lens and convex mirror

Answer :  A

Question : A Concave Mirror Produces Magnification Of +4. The Object Is Place(d)
(a) At the focus
(b) Between focus and centre of curvature
(c) Between focus and pole
(d) Beyond the centre of curvature

Answer :  C

Question : Magnification produced by a rear view mirror fitted in vehicles
(a) is less than one
(b) is more than one
(c) is equal to one
(d) can be more than or less than one depending upon the position of the object in front of it

Answer :  A

Question : The refractive index of a medium with respect to vacuum is
(a) Always greater than one
(b) Always less than one
(c) Equal to one
(d) none of the above

Answer :  B

Question : A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.
(a) Plane, convex and concave
(b) Convex, concave and plane
(c) Concave, plane and convex
(d) Convex, plane and concave

Answer :  C

Question : The distance between the object and image will be
(a) 0.25 m
(b) 1.0 m
(c) 0.5 m
(d) 0.125 m

Answer :  C

Question : Magnification produced by a plane mirror is
(a)-1
(b) zero
(c) +1
(d) infinity

Answer :  C

Question : Mirror used for focusing light is
(a) Concave
(b) Convex
(c) plane
(d) none

Answer :  A

Question : What will be the angle of refraction for a ray of light fall perpendicular to the interface of two mediums?
(a) 90o
(b) 0o
(c) 180o
(d) 45o

Answer :  B

Question : Focal length of a convex lens is 15 cm. For which distance an object is placed so that the lens acts as a magnifying glass?
(a) Between 15 cm and 30 cm
(b) Less than 15 cm
(c) Greater than 30 cm
(d) Exactly at 30 cm

Answer :  B

Question : A ray of light strikes the surface of mirror at an angle of 300 with the mirror. The angle of reflection is:
(a) 300
(b) 600
(c) 450
(d) none.

Answer :  B

Question : An object 20cm high is placed at a distance of 100 cm from a plane mirror .The size of the image will be.
(a) 20 cm
(b) 40cm
(c) 10cm
(d) 100cm

Answer :  A

Question : Velocity of light in vacuum is
(a) 3×10⁸ cm/s
(b) 3×10⁸ km/s
(c) 3×10⁸m/s
(d) none of these

Answer :  C

Question : A concave mirror is a part of a sphere of radius 30cm.It’s focal length is
(a) at infinity
(b)10cm
(c)15cm
(d) 60cm

Answer :  C

Question : Focal length of plane mirror is

(a) at infinity
(b) zero
(c) negative
(d) none of these

Answer :  A

Question : A concave mirror gives, real, inverted and same size image if the object is placed
(a) at F
(b) at infinity
(c) at C
(d) beyond C

Answer :  C

Question : A concave mirror gives virtual, erect and enlarged image if the object is placed:
(a) at infinity
(b) between F and C
(c) between P and F
(d) at F.

Answer :  C

Question : All the distances in case of spherical mirror are measured in relation to
(a) object to image
(b) the pole of the mirror
(c) the focus of the mirror
(d) the image to the object.

Answer :  B

Question : The object distance in both concave as well as convex mirror is
(a) negative
(b) positive
(c) zero
(d) none of these

Answer :  A

Question : In optics an object which has higher refractive index is called
(a) optically rarer
(b) optically denser
(c) optical density
(d) refractive index

Answer :  B

Question : Convex lens focus a real, point sized image at focus, the object is placed
(a) at focus
(b) between F and 2f
(c) at infinity
(d) at 2f

Answer :  C

Question : The radius of curvature of a mirror is 20 cm the focal length is
(a) 20 cm
(b) 10 cm
(c) 40 cm
(d) 5 cm

Answer :  B

Question : The power of a lens is + 1.6 D. The nature of lens is
(a) Convex lens
(b) Concave lens
(c) both concave an convex
(d) none of these

Answer :  A

Question : If the object is placed at focus of a concave mirror, the image is formed at
(a) infinity
(b) focus
(c) centre of curvature
(d) between F and O.

Answer :  A