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NCERT Solutions for Class 10 Science Chapter 10 Light - Reflection and Refraction- This article includes free NCERT Solutions for Class 10 Science Chapter 10 Light - Reflection and Refraction, developed by the top Biology experts at GFG, according to the latest CBSE Syllabus 2023-24 and guidelines. The solutions to all the exercises in NCERT Class 10 Science Chapter 10 Light - Reflection and Refraction have been collectively covered in NCERT Solutions for Class 10.
Also, to learn the basic concepts of NCERT Class 10 Chapter 10 Light - Reflection and Refraction from scratch, check out Class 10 NCERT Science Chapter 10 Light - Reflection and Refraction.
We cannot use clay to make lens because clay is an opaque material and light cannot pass through clay. Thus we cannot see anything through a clay lens.
Thus option (d) clay is the correct answer.
Concave image forms a virtual, erect and larger image when the object is between the principal focus and pole of the mirror.
Thus option (d) is the correct answer.
To get a real image of the object through a convex lens, we need to place the object at a distance equal to radius of curvature of the lens which is twice the focal lengh.
Thus option (b) is the correct answer.
The focal length given here is negative. Negative focal length is a property of concave mirror. Thus the mirror and lens both are concave.
Thus option (a) is the correct answer.
A plane and convex mirror always form an erect image. Thus the mirror is likely to be either plane or convex.
Thus option (d) is the correct answer.
A mirror with shorter focal length has a higher magnification power and a convex lens makes an erect image when object is between the mirror and its focal length. Thus we will make use of a convex mirror with focal length of 5cm.
Thus option (c) is the correct answer.
A concave mirror will form an erect image of an object when the distance of object from the mirror is less than its focal length. Thus we will place the image between 0 to 15 cm. The image thus formed is virtual, erect, and enlarged (larger than the object). The ray diagram is shown below:
👁 ray diagram of reflection from a concave mirror
(a) A concave mirror is used in the headlights of car because when the light source is placed at the focus of the concave mirror, it produces a powerful parallel beam of light which helps to see the objects on the front of car clearly to a large distance.
(b) Side/ rear view mirror of a vehicle is a convex mirror because we need to see a large amount of area and vehicles behind us while driving. A convex mirror is used because a convex mirror forms a virtual and diminished image of the objects which provide us with a smaller view of the large area.
(c) Solar furnace makes use of concave mirror because the sun's rays coming from infinity are converged by the concave mirror at its focus which concentrates the energy at a particular point to produce a high temperature.
Yes, the lens will produce a complete image of the object but the image will be reduced in intensity. This is because to form an image, we need only two rays of light coming from an object. As the upper portion of lens is not covered, at least two rays can pass through upper part of lens and form the image. This can be verified by an experiment.
Experiment: To show that a half lens can produce a complete image of an object
Requirements: Convex lens, Candle, matchstick, Two black sheets of paper, Table
Procedure:
👁 Ray Diagram of Reflection through Convex Lens
- Fix the convex lens on the table.
- Now light a candle with matchstick and place it on one side of the lens.
- Turn off the lights to ensure that the room is dark
- Take a sheet of paper and obtain the image of the candle on the sheet by moving it.
- Mark the positions of the candle, lens and image in this case.
- Now, cover one half of the lens with a black sheet.
- Repeat the above experiment.
Observations: A complete image of candle is obtained on the sheet but it is less bright as compared to previous image.
Thus, we conclude that a half lens can form a complete image of an object.
Given u = -25 cm, h = 5cm, f = 10 cm, h' = ?
Using lens formula: 1/f = 1/v - 1/u
1/10 = 1/v - (-1/25)
1/v = 1/10 - 1/25
1/v = 15/250 = 3/50
v = 50/3 cm = 16.67 cm
We know that h/h' = v/u
5/h' = 50/3*(-25)
h' = 250/(-75) = -10/3
h' = 3.33 cm
Negative sign indicates that the image is inverted and diminished in size as h' < h. It is formed at a distance of 16.67 cm behind the lens.
The ray diagram is shown below:
Given u = ?, f = -15 cm, v = -10 cm
Using lens formula:
1/f = 1/v - 1/u
-1/15 = -1/10 - 1/u
1/u = -1/10 + 1/15
1/u = -5/150
u = -30 cm
Thus, the object is placed at a distance of 30 cm in front of the lens.
The ray diagram is shown below:
Given u = -10 cm, f = 15 cm
Using mirror formula : 1/f = 1/v + 1/u
1/15 = 1/v + (-1/10)
1/v = 1/15 + 1/10
1/v = 25/250
v = 6 cm
Magnification = -v/u = -6/-10 = 0.6 < 1
Thus a diminished image is formed at a distance 6 cm behind the mirror.
As magnification = h'/h. A magnification of 1 means that the height of image is same as the height of object and a positive sign indicates that the image is virtual and erect.
Given h = 5 cm, u = -20 cm, R = 30 cm
As R = 2f
30 = 2f
f = 15 cm
Using mirror formula:
1/f = 1/v + 1/u
1/15 = 1/v - 1/20
1/v = 1/15 + 1/20
1/v = 35/300
v = 300/35 = 8.57 cm
Magnification m= -v/u = -8.57/-20 = 0.428
m = h'/h
0.428 = h'/5
h' = 2.14 cm
As m < 1, v is positive and h' < h, a virtual , erect and diminished image of size 2.14 cm is formed.
Given h = 7, u = -27 cm, f = -18 cm, v = ?
Using mirror formula:
1/f = 1/v + 1/u
-1/18 = 1/v - 1/27
1/v = -1/18 + 1/27
1/v = -1/54
v = -54 cm
Magnification m= -v/u = 54/-27 = -2
As m > 1 and has a negative sign, a real, inverted and magnified image of double the size of the object is formed at a distance of 54 cm in front of the mirror.
Given P = -2.0 D
We know that 1/f = P
1/f = -2
f = -1/2 = -0.5 m = -50cm
As the focal length is negative, it is a concave lens.
Given P = 1.5 D
We know that 1/f = P
1/f = 1.5
f = 1/1.5 = 0.667m
Thus the focal length is 0.667 m. As the focal length is positive, it is a convex lens which is converging lens.
The topics covered in Chapter 10 'Light-Reflection and Refraction' chapter in Class 10 NCERT Science are:
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