MP Board Class 10th Science Chapter 10 Solutions Light Reflection And Refraction

In this article, we will share MP Board Class 10th Science Chapter 10 Light Reflection And Refraction Solution with free pdf file.

What’s we cover in this article

  • 10th Science Chapter 10 Tick the correct answer
  • 10th Science chapter 10 Fill in the blanks
  • 10th science chapter 10 true or false
  • 10th science chapter 10 match the pair
  • 10th science chapter 10 very short answer type questions
  • 10th science chapter 10 short answer type questions
  • 10th science chapter 10 long answer type questions

Light Reflection And Refraction Textbook Exercises

Question 1.
Which one of the following materials cannot be used to make a lens?
(a) Water
(b) Glass
(c) Plastic
(d) Clay
Answer:
(d) A lens allows light to pass through it, but clay does not have that property.

Question 2.
The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should be the position of the object?
(a) Between the principal focus and the centre of curvature
(b) At the centre of curvature
(c) Beyond the centre of curvature
(d) Between the pole of the mirror and its principal focus.
Answer:
(d) Between the pole of the mirror and its principal focus.

Question 3.
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
(a) At the principal focus of the lens
(b) At twice the focal length
(c) At infinity
(d) Between the optical centre of the lens and its principal focus.
Answer:
(b) When an object is placed at the centre of curvature in front of a convex lens, its image is formed at the centre of curvature on the other side of the lens.

Question 4.
A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The mirror and the lens are likely to be:
(а) both concave
(b) both convex
(c) the mirror is concave and the lens is convex
(d) the mirror is convex, but the lens is concave
Answer:
(а) both concave

Question 5.
No matter how far you stand from a mirror, your image appears erpct. The mirror is likely to be
(a) plane
(b) concave
(c) convex
(d) either plane or convex
Answer:
(d) either plane or convex

Question 6.
Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm
(b) A concave lens of focal length 50 cm
(c) A convex lens of focal length 5 cm
(d) A concave lens of focal length 5 cm
Answer:
(c)

Question 7.
We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.
Answer:
Range of the distance of the object = 0 cm to 15 cm.
Nature of the image = virtual, erect and larger than the object.

MP Board Solutions

Question 8.
Name the type of mirror used in the following situations.
(a) Headlights of a car.
(b) Side/rear-view mirror of a vehicle.
(c) Solar furnace.
Support your answer with reason.
Answer:
(a) Concave mirror: Concave mirrors can produce powerful parallel ’ beam of light when the light source is placed at their principal focus. Hence, we can visualize ways easily in little light.

(b) Convex mirror: A convex mirror when fitted at rear view position of vehicles, it gives a wider field of view, with which driver can see most of the traffic behind him.

(c) Concave mirror: They are converging mirrors. This is because it concentrates the parallel rays of sun at principal focus and increase intensity of light falling on it.

10th Science Chapter 10 Solutions Light Reflection And Refraction

Question 9.
One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.
Answer:
Yes, the convex lens will form complete image of the object, even if its one half is covered with black paper. Following two cases can better explain it:

Case I : When the upper half of the lens is covered.
In this case, a ray of light coming from the object is being refracted by the lower half of the lens. These rays meet at the other side of the lens to form the image of the given object.

MP-Board-Class-10th-Science-Solutions-Chapter-10-Light-Reflection-and-Refraction-7
MP-Board-Class-10th-Science-Solutions-Chapter-10-Light-Reflection-and-Refraction-8

Question 10.
An object 5 cm in length.is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.
Answer:
Converging lens means a convex lens. As the distances given in the question are large, so we choose a scale of 1 : 5, i.e., 1 cm represents 5 cm. Therefore, on this scale 5 cm high object, object distance of 25 cm and focal length of 10 cm can be represented by 1 cm high, 5 cm and 2 cm lines respectively. Now, we draw the ray diagram as follows;

  1. Draw a horizontal line to represent ‘die principal axis of the convex lens.
  2. Centre line is shown by DE.
  3. Mark two foci F and F’ on two sides of the lens, each at a distance of 2 cm from the lens.
  4. Draw an arrow AB of height 1 cm on the left side of lens at a distance of 5 cm from the lens.
  5. Draw a line AD parallel to principal axis and then allow it to pass straight through the focus (F’) on the right side of the lens.
Draw-a-horizontal-line-to-represent-‘die-principal-axis-of-the-convex-lens.
  1. Draw a line from A to C (centre of the lens), which goes straight without deviation.
  2. Let the two lines starting from A meet at A’.
  3. Draw A’B’, perpendicular to the principal axis from A’.
  4. Now A’B represents the real, but inverted image of the object AB.
  5. Then, measure CB’ and A’B’. It is found that CB’ = 3.3 cm and A’B’ = 0.7 cm.
  6. Thus the final position, nature and size of the image A’B’ are
    • (a) Position of image A’B’ = 3.3 cm × 5 = 16.5 cm from the lens on opposite side.
    • (b) Nature of image A’B’: Real and inverted.
    • (c) Height of image A’B’: 0.7 × 5 = 3.5 cm, i.e., image is smaller than the object.

Question 15
An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained? Find the size and the nature of the image.
Answer:
Object-distance, u = – 27 cm
Object-height, h = 7 cm
Focal length, f = – 18 cm
According to the mirror formula,
1v + 1u = 1f
Putting values, 1v + 1(−27) = 1(−18)
So, v = – 54 cm
The screen should be placed at a distance of 54 cm in front of the given mirror
and h2h1=−vu
h2 = -14 cm
The negative value of image indicates that the image is inverted.

Question 16.
Find the focal length of a lens of power – 2.0 D. What type of lens is this?
Answer:
Given, P = -2D
Power of lens. p = 1f
and, f = – 12
h2h1=−vu
= – 0.5 m
A concave lens, because it has a negative value of focal length.

Question 17.
A doctor has prescribed a corrective lens of power + 1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
Answer:
Given, P = 1.5.D
Power of lens, P = 1f
and, focal length f = 11.5
= 1015 = 0.66 m
A convex lens, because it has a positive focal length. Lens is converging.

MP Board Solutions

MP Board Class 10th Science Chapter 10 Additional Important Questions

Multiple Choice Questions

Question 1.
The image formed by a convex lens is virtual, erect and larger than the object. The position of the object must be:
(a) Between the lens and its focus
(b) At the focus
(c) At twice the focal length
(d) At infinity
Answer:
(a) Between the lens and its focus

Question 2.
A real image formed by a convex lens is always:
(a) On the same side of the lens as the object
(b) Erect
(c) Inverted
(d) Smaller than the object
Answer:
(c) Inverted

Question 3.
If an object is moved towards a convex lens, the size of its image:
(a) Decreases
(b) Increases
(c) First decreases and then increases
(d) Remains the same
Ans.
(b) Increases

Question 4.
An object is placed at a distance of 30 cm from a concave mirror of focal length 15 cm. The image will be:
(a) Real and of same size
(b) Real and magnified
(c) Real and diminished
(d) virtual and magnified
Answer:
(a) Real and of same size

Question 5.
A concave mirror always forms real and inverted image except when the object is placed:
(a) At infinity
(b) Between F and C
(c) At F
(d) Between F and pole of the mirror
Answer:
(b) Between F and C

Question 6.
The mirror which has a wide field of view must be:
(a) Concave
(b) Convex
(c) Plane
(d) None of these
Ans.
(b) Convex

10th Science Chapter 10 question answer pdf

Question 7.
The image formed by a concave mirror:
(a) Is always real
(b) Is always virtual
(c) Can be both real and virtual
(d) None of these
Ans.
(c) Can be both real and virtual

Question 8.
An object is placed 20 cm from a convex lens of focal length 10 cm. The image must be:
(a) Real and diminished
(b) Real and of same size
(c) Real and enlarged
(d) Virtual and enlarged
Answer:
(b) Real and of same size

Question 9.
The ratio of the focal length of spherical mirror to its radius of curvature is:
(a) 0.5
(b) 1
(c) 2
(d) 3
Answer:
(a) 0.5

Question 10.
A real and inverted image of the same size is formed by a concave mirror when the object is placed:
(a) Between the mirror and its focus.
(b) Between the focus and the centre of curvature.
(c) At the centre of curvature.
(d) Beyond the centre of curvature.
Ans.
(c) At the centre of curvature.

MP Board 10th science Solutions

Very Short Answer Type Questions

Question 1.
What is a mirror? Mention the different types of mirrors commonly used.
Answer:
Mirror: A highly polished surface which is smooth enough to reflect a good fraction of light incident on it is called a mirror. The mirror may be a highly polished metal surface or an ordinary glass plate coated with a thin silver layer.

Question 2.
What is the number of images of an object held between two plane parallel mirrors?
Answer:
Infinity.

Question 3.
Does the refractive index for a given pair of media depend on the angle of incidence?
Answer:
No, it is independent of the angle of incidence.

Question 4.
The refractive index of water with respect to air is 43. What is the refractive index of air with respect to water?
Answer:
Refractive index of air with respect to water = 34

Question 5.
Can absolute refractive index of a medium exceed unity?
Answer:
No, because speed of light is maximum in vacuum.

Question 6.
Why does a ray of light bend when it travels from one medium to another?
Answer:
The bending of light or refraction occurs due to the change in the speed of light as it passes from one medium to another due to change in the density of the medium.

Question 7.
What happens when a ray of light strikes the surface of separation between the two media at right angle?
Ans.
The ray of light passes undeflected from one medium to another.
Here, ∠i = ∠r = 0°

Question 8.
What do you mean by a magnification less than unity?
Answer:
It means that the size of the image is smaller than the size of the object.

Question 9.
Which spherical mirror has

  1. a real focus and
  2. a virtual focus?

Answer:

  1. A concave mirror has a real focus.
  2. A convex mirror has a virtual focus.

Question 10.
State the position of the object for which a concave mirror produces virtual magnified image.
Answer:
The object should be placed between F and P of the concave mirror.

Short Answer Type Questions

Question 1.
Explain the uses of concave and convex mirrors.
Answer:
Uses of concave mirrors:
1. Shaving mirror : A concave mirror is used as a shaving or make-up mirror because it forms erect and enlarged image of the face when it is held closer to the face.

2. As head mirror : E.N.T. specialists use a concave mirror on their forehead. The light from a lamp after reflection from the mirror is focussed into the throat, ear or nose of the patient making the affected part more visible.

3. In ophthalmoscope : It consists of a concave mirror with a small hole at its centre. The doctor looks through the hole from behind the mirror while a beam of light from a lamp reflected from it, is directed into the pupil of patient’s eye which makes the retina visible.

4. In headlights : Concave mirrors are used as reflectors in headlights of motor vehicles railway engines, torch lights etc. The source is placed at the focus of the concave mirror. The light rays after reflection travel over a. large distance as a parallel beam of high intensity.

5. In astronomical telescopes : A concave mirror of large diameter (5 m or more) is used as objective in an astronomical telescope. It collects light from the sky and makes visible even those faint stars which cannot be seen with naked eye.

6. In solar furnaces : Large concave mirrors are used to concentrate sunlight to produce heat in solar furnace.

Uses of convex mirrors : Drivers use convex mirror as a rear-view mirror in automobiles because of the following two reasons:

  1. A convex mirror always forms an erect, virtual and diminished image of an object placed anywhere in front of it.
  2. A convex mirror has a wider field of view than a plane mirror of the same size as shown in Fig. 10.5.
Light Reflection and Refraction
Fig. 10.5: Field of view of (a) a plane mirror, (b) a convex mirror.

Thus, convex mirrors enable the driver to view much larger traffic behind him than would be possible with a plane mirror. The main disadvantage of a convex mirror is that it does not give the correct distance and the speed of the vehicle approaching from behind.

MP Board 10th Science Chapter 10 Solutions Light Reflection And Refraction

Question 2.
What is the physical significance of refractive index?
Answer:
The refractive index of any medium gives the ratio of the speed of light in vacuum to the speed of light in that medium. For example, the refractive index of water, µw = 1.33. This means that the ratio of the speed of light in vacuum or air to the speed of light in water is 1.33.

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