# Class 10 Science Chapter 10 Light-Reflection and Refraction

Class 10 Science Chapter 10 Light-Reflection and Refraction The answer to each chapter is provided in the list so that you can easily browse throughout different chapters NCERT Class 10 Science Chapter 10 Light-Reflection and Refraction and select need one.

### Class 10 Science Chapter 10 Light-Reflection and Refraction

Also, you can read the SCERT book online in these sections Solutions by Expert Teachers as per SCERT (CBSE) Book guidelines. These solutions are part of SCERT All Subject Solutions. Here we have given Assam Board Class 10 Science Chapter 10 Light-Reflection and Refraction Solutions for All Subjects, You can practice these here…

Multiple Choice Questions

Q.1. The angle of reflection is equal to the angle of incidence

( a ) Always.

( b ) Sometimes.

( c ) Under special conditions.

( d ) Never.

Ans :- ( a ) Always.

Q.2. The angle between and incident ray and the plane mirror is 30°. The total angle between the incident ray and reflected ray will be :

( a ) 30°

( b ) 60°

( c ) 90°

( d ) 120°

Ans :- ( d ) 120°

Q.3. A ray of light is incident on a plane mirror making an angle of 90° with the mirror surface. The angle of reflection for this ray of light will be.

( a ) 45°

( b ) 90°

( c ) O°

( d ) 60°

Ans :- ( c ) O°

Q.4. The image of an object formed by a plane mirror is-

( a ) Virtual.

( b ) Real.

( c ) Diminished.

( d ) Upside-down.

Ans :- ( a ) Virtual.

Q.5. The image formed by a plane mirror is :

( a )  Virtual, behind the mirror and enlarged.

( b )  Virtual, behind the mirror and of the same size as the object.

( c ) Real, behind the mirror and of the same size with object.

( d ) Real, at the surface of the mirror and enlarged.

Ans :- ( b ) Virtual, behind the mirror and of the same size as the object.

Q.6. In a convex spherical mirror, reflection of light takes place at :

( a ) A flat surface.

( b ) A bent in surface.

( c ) A bulging surface.

( d ) An uneven surface.

Ans :- ( c ) A bulging surface.

Q.7. A diverging mirror is :

( a ) A plane mirror.

( b ) A convex mirror.

( c ) A concave mirror.

( d ) A shaving mirror.

Ans :- ( b ) A convex mirror.

Q.8. If R is the radius of curvature of a spherical mirror and f is its focal length, then :

( a ) R = f

( b ) R = 2f

( c ) R = f/2

( d ) R = 3f

Ans :-  ( b ) R = 2f

Q.9. The focal length of a spherical mirror of radius of carvature 30 cm. is :

( a ) 10 cm

( b ) 15 cm

( c ) 20 cm

( d ) 30 cm

Ans :- ( b ) 15 cm.

Q.10. If the focal length of a spherical mirror is 12.5 less cm. its radius of curvature will be :

( a ) 25 cm

( b ) 15cm

( c ) 20cm

( d ) 35cm

Ans :- 25 cm.

Q.11. The real image formed by a concave mirror is larger than the object when the object is :

( a ) At a distance equal to radius of curvature.

( b ) At a distance less than the focal length.

( c ) Between focus and centre of curvature.

( d ) At a distance greater than radius of curvature.

Ans :- ( c ) Between focus and centre of curvature.

Q.12. The real image formed by a concave mirror is smaller than the object if the object is :

( a ) Between centre of curvature and focus.

( b ) At a distance greater than radius of curvature.

( c ) At a distance equal to radius of curvature.

( d ) At a distance equal to focal length.

Ans :- ( b ) At a distance greater than radius of curvature.

Q.13. The image formed by a concave mirror is virtual, erect and magnified. The position of object is :

( a ) At focus.

( b ) Between focus and centre of curvature.

( c ) At pole.

( d ) Between pole and focus.

Ans :- ( d ) Between pole and focus.

Q.14. The image formed by a concave mirror is real, inverted and of the same size as the object. The position of the object must then be :

( a ) At the focus.

( b ) Between the centre of curvature and focus.

( c ) At the centre of curvature.

( d ) Beyond the centre of curvature.

Ans :- ( c ) At the centre of curvature.

Q.15. The image formed by a concave mirror is real, inverted and highly diminished. The object must be :

( a ) Between pole and focus.

( b ) At focus.

( c ) At the centre of curvature.

( d ) At infinity.

Ans :- ( d ) At infinity.

Q.16. The angle of incidence for a ray of light passing through the centre of curvation of a concave mirror is

( a ) 45°

( b ) 90°

( c ) O°

( d ) 180°

Ans :- ( c ) O°

Q.17. One of the following does not apply to a concave mirror, This is :

( a ) Focal length is negative.

( b ) Image distance can be positive or negative.

( c ) Image distance is always positive.

( d ) Height of image can be positive or negative.

Ans :- ( c ) Image distance is always positive.

Q.18. Linear magnification produced by a concave mirror may be :

( a ) Less than 1 or equal to 1

( b ) More than 1 or equal to 1

( c ) Less than 1, more than 1 or equal to 1

( d ) Less than 1 or more than 1

Ans :- ( c ) Less than 1, more than 1 or equal to 1

Q.19. Magnification produced by a convex mirror is always :

( a ) More than 1

( b ) Less than 1

( c ) Equal to 1

( d ) More or less than 1

Ans :- ( b ) Less than 1

Q.20. Magnification produced by a plane mirror is

( a ) Less than one.

( b ) Greater then one.

( c ) Zero.

( d ) Equal to one.

Ans :- ( d ) Equal to one.

Q.21.The image formed by a spherical mirror is virtual. The mirror will be :

( a ) Concave.

( b ) Convex.

( c ) Either concave or convex.

( d ) Metallic.

Ans :- ( c ) Either concave or convex.

Q.22. The mirror used by a dentist to examine the teeth of person is :

( a ) Convex.

( b ) Concave.

( c ) Plane.

( d ) Any one of the above.

Ans :- ( b ) Concave.

Q.23. If the image formed is always virtual, the mirror can be

( a ) Concave or convex.

( b ) Concave or plane.

( c ) Convex or plane.

( d ) Only convex.

Ans :- ( c ) Convex or plane.

Q.24. The mirror which can form a magnified image of an object is :

( a ) Convex mirror.

( b ) Plane mirror.

( c ) Concave mirror.

( d ) Both convex and concave mirrors.

Ans :- ( c ) Concave mirror.

Q.25. Tight travelling from a denser medium to rarer medium along a normal to the boundary.

( a ) Is refracted towards the normal.

( b ) Is refracted away from the normal.

( c ) Goes along the boundary.

( d ) Is not refracted.

Ans :- ( d ) Is not refracted.

Q.26. A ray of light travelling in air goes into water. The angle of refraction will be :

( a ) 90°

( b ) Smaller than the angle of incidence.

( c ) Equal to the angle of incidence.

( d ) Greater than the angle of incidence.

Ans :- ( b ) Smaller than the angle of incidence.

Q.27. The speed of light in air is

( a ) 3×10⁸ cm/s

( b ) 3×10⁸ mm/s

( c ) 3×10⁸ km/s

( d ) 3×10⁸ m/s

Ans :- ( d ) 3×10⁸ m/s

Q.28. A ray of light passes from medium X to another medium Y. No refraction of light occurs if the of light with the boundary of medium Y at an angle of

( a ) 0°

( b ) 45°

( c ) 90°

( d ) 120°

Ans :- ( c ) 90°

Q.29. The speed of light in substance X is 1.25×10⁸ m/s and that in air is 3×10⁸m/s. The refractive index of this substance will be :

( a ) 2.4

( b ) 0.4

( c ) 4.2

( d ) 3.75

Ans :- ( a ) 2.4

Q.30. The refractive index of water is

( a ) 1.33

( b ) 1.50

( c ) 2.42

( d ) 1.36

Ans :- ( a ) 1.33

Q.31. The refractive index of water with respect to air is 4/3 The refractive index of air with respect to water will be :

( a ) 1.75

( b ) 0.50

( c ) 0.75

( d ) 0.25

Ans :- ( c ) 0.75

Q.32. Which one of the following materials cannot be used to make a lens?

( a ) Water.

( b ) Glass.

( c ) Plastic.

( d ) Clay.

Ans :- ( d ) Clay.

Q.33. An object is placed between f and 2f of a convex lens. Which of the following statements correct describes its image?

( a ) Real, larger than the object.

( b ) Erect, smaller than the object.

( c ) Inverted, same size as object.

( d ) Virtual, larger than the object.

Ans :- ( a ) Real, larger than the object.

Q.34. A spherical mirror and a spherical lens each have a focal length of -15 cm. The mirror and the lens are likely to be :

( a ) Both concave.

( b ) Both convex.

( c ) The mirror is concave but the lens is convex.

( d ) The mirror is convex but the lens is concave.

Ans :- ( a ) Both concave.

Q.35. Magnification produced by a concave lens is always :

( a ) More than 1

( b ) Equal to 1

( c ) Less than 1

( d ) More than 1 or less than 1

Ans :- ( c ) Less than 1

Q.36. A convex lens produces a magnification of +5. The object is placed :

( a ) At focus.

( b ) Between f and 2f

( c ) At less than f

( d ) Beyond 2f

Ans :- ( c ) At less than f

Q.37. An object is 0.09 m from a magnifying lens and the image is formed 36cm. from the lens. The magnification produced is :

( a ) 0.4

(b) 1.4

( c ) 4.0

( d ) 4.5

Ans :- ( c ) 4.0

Q.38. A diverging lens is used in :

( a ) A magnifying glass.

( b ) A car to see objects on rear side.

( c ) Spectacles for the correction of short sight.

( d ) A simple camera.

Ans :- ( c ) Spectacles for the correction of short sight.

Q.39. When an object is kept at any distance in front of a concave lens, the image formed is always :

( a ) Virtual, erect and magnified.

( b ) Virtual, inverted and diminished.

( c ) Virtual, erect and diminished.

( d ) Virtual, erect and same size as object.

Ans :- ( c ) Virtual, erect and diminished.

Q 40. A concave lens produces an image 20cm from the lens of an object planed 30 cm form the lens. The focal length of the lens is :

( a ) 50 cm.

( b ) 40 cm.

(c) 60 cm.

( d ) 30 cm.

Ans :- (c) 60 cm.

Q.41. Only one of the following applies to a concave lens. This is

( a ) Focal length is positive.

( b ) Image distance can be positive or negative.

( c ) Height of image can be positive or negative.

( d ) Image distance is always negative.

Ans :- ( d ) Image distance is always negative.

Q.42. The magnification produced by a spherical mirror and a spherical lens is +0.8.

( a ) The mirror and lens are both convex.

( b ) The mirror and lens are both concave.

( c ) The mirror is concave but the lens is convex.

( d ) The mirror is convex but the lens is concave.

Ans :- ( d ) The mirror is convex but the lens is concave.

Q.43. The focal lengths of four convex lenses P, Q, R and S are 20cm, 15cm, 5 cm and 10 cm respectively. The lens having greatest power is :

( a ) P

( b ) Q

( c ) R

( S ) S

Ans :- ( c ) R

Q.44. A converging lens has a focal length of 50 cm. The power of this lens is :

( a ) +0.2 D

( b ) –2.OD

(c) +2.0 D

( d ) –0.2 D

Ans :- ( c ) +2.0 D

Q.45. A diverging lens has a focal length of 0.10 m. The power of this lens will be :

( a ) +10.0 D

( b ) +1.0 D

( c ) –1.0 D

( d ) –10.0 D

Ans :- ( d ) –10.0 D

Q.46. The power of a lens is +2.0 D. Its focal length should be :

( a ) 100 cm.

( b ) 50 cm.

( c ) 25 cm.

( d ) 40 cm.

Ans :- ( b ) 50 cm.

Q.46. If a spherical lens has a power of -0.25 D, the focal length of this lens will be :

( a ) –4 cm.

( b ) –400 mm

( c ) –4m

( d ) –40m

Ans :- ( c ) –4m.

Q.48. The power of a concave lens is 10 D and that of a convex le lens is D. When these two lenses are placed in contract with each other, the power of their combination will be :

( a ) +16 D

( b ) +4 D

(c) –16 D

( d ) –4 D

Ans :- ( d ) –4 D.

Q.49. The powre of a converging lens is 4.5 D and that of a diverging lens is D. The power of this combination of lenses placed close together is :

( a ) +1.5 D

( b ) +7.5 D

( c ) –7.5 D

( d ) –1.5 D

Ans :- ( a ) +1.5 D.

Q.50. A convex lens of focal length 10 cm. is placed in contact with a concave lens of focal length 20 cm. The focal m length of this combination of lenses will be :

( a ) +10 cm

( b ) +20 cm

( c ) –10 cm

( d ) –20 cm

Ans :- ( b ) +20 cm

Q.1. Define luminous objects.

Ans :- The objects like the sun, other stars, electric bulb, tube light, torch, candle and fire etc., which emit their own light are called luminous objects.

Q.2. Define non-luminous objects. Give example.

Ans :- Those objects which do not emit light themselves but only reflect or scatter the light which falls on them are called non-luminous objects.

Examples :- Chair, table, book, human bings, mirror etc.

Q.3. Write the laws of reflection.

Ans :- The laws of reflection are :-

( i ) The incident ray, the reflected ray and the normal at the point miler of incidence all lie in the same plane.

( ii ) The angle of reflection is always equal to the angle of incidence.

Q.4. What do you mean by lateral inversion?

Ans :- When an object is placed in front of a plane mirror, then the right side of object appears to become the left side of image and the left side of object appears to become the right side of image. This change of sides of an object and its mirror image is called lateral inversion.

Q.5. What are the characteristics of an image formed by a plane mirror?

Ans :- The characteristics are

( i ) The image formed in a plane mirror is virtual.

( ii ) The image formed in a plane mirror is erect. It is the same side up as the object.

( iii ) The image in a plane mirror is of the same size as the object.

( iv ) The image formed by a plane mirror is at the same distance behind the mirror as the object is in front of the mirror.

( v ) The image formed in a plane mirror is laterally inverted.

Q.6. What happens when a ray of light falls normally or perpendicularly on the surface of a plane mirror?

Ans :- A ray of light falls normally or perpendicularly on a plane mirror is reflected back along the same path because the angle of incidence, as well as the angle of reflection for such a ray of light, are zero.

Q.7. A ray of light is incident normally on a plane mirror. What will be the :

( a ) Angle of incidence?

( b ) Angle of reflection?

Ans :- ( a ) 0°

( b ) 0°

Q.8. Define the following for a spherical mirror :

( a ) Pole.

( b ) Principal axis.

( c ) Focal length.

Ans :- ( a ) Pole :- The centre of a spherical mirror is called its pole.

Principal axis :- The straight line passing through the centre of curvature and pole of a spherical mirror is called its principal axis.

( c ) Focal length :- The focal length of a concave mirror is the distance between its pole and principal focus.

Q.9. Name the spherical mirror which has :

( a ) Virtual principal focus.

( b ) Real principal focus.

Ans :- ( a ) Convex mirror.

( b ) Concave mirror.

Q.10. Define refraction of light. Write the laws of refraction.

Ans :- The change in direction of light when it passes from one medium to another obliquely, is called refraction of light.

Laws of refraction are :-

( i ) The incident ray, the refracted ray and the normal at the point of incidence, all lie in the same plane.

( ii ) The ratio of sign of angle of incidence to the sine of angle of refraction is constant for a given pair of media.

Numerical Problems

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