# Notes And Questions For NCERT Class 10 Science Light Reflection and Refraction

Students should refer to the below Light Reflection and Refraction Class 10 notes prepared as per the latest curriculum issued by CBSE and NCERT. These notes and questions are really useful as they have been developed based on the most scoring topics and expected questions in upcoming examinations for Class 10. Light Reflection and Refraction is an important topic in Science Class 10 which if understood properly can help students to get very good marks in class tests and exams.

## Light Reflection and Refraction Class 10 Notes and Questions PDF Download

Read the notes below which will help you to understand all important and difficult topics in this chapter. There are some topics in Light Reflection and Refraction chapter which you should understand carefully as many questions can come from those parts. Our team of teachers have designed the revision notes so that its helpful for students to revise entire course prior to the class tests.

### MCQ Questions Light Reflection and Refraction Class 10 Science

Question. The figure shows a ray of light as it travels from medium A to medium B. The refractive index of the medium B relative to medium A is:

(a) √3/√2
(b) √2/√3
(c) 1/√2
(d) √2

A

Question. You are given water, mustard oil, glycerine and kerosene. In which of these media, a ray of light incident obliquely at some angle would bend the most? (Refractive index of nater = 1.33, Musterd oil = 1.46, Glycerin = 1.473, Kerosine = 1.44)
(a) Kerosene
(b) Water
(c) Mustard oil
(d) Glycerine

D

Question. A student obtains a blurred image of a distant ob􀅉ect on a screen using a convex lens. To obtain a distinct image on the screen he should move the lens:
(a) away from the screen
(b) towards the screen
(c) to a position very far away from the screen
(d) either towards or away from the screen depending upon the position of the object

D

Question. A light ray enters from medium A to medium B as shown in the figure. The refractive index of medium B relative to A will be:

(a) Greater than unity
(b) Less than unity
(c) Equal to unity
(d) Zero

A

Question. Rays from the sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that the size of its image is equal to the size of the object?
(a) 15 cm in front of the mirror.
(b) 30 cm in front of the mirror.
(c) Between 15 cm and 30 cm in front of the mirror.
(d) More than 30 cm in front of the mirror.

B

Question. When object moves closer to convex lens, the image formed will be
(a) away from the lens on the other side of lens.
(b) towards the lens.
(c) away from the lens on the same side of an object.
(d) first towards and then away from the lens.

C

Question. A student has focussed on the screen a distant building using a convex lens. If he has selected a blue coloured building as object, select from the following options the one which gives the correct characteristics of the image formed on the screen.
(a) Virtual, erect, diminished and green shade
(b) Real, inverted, diminished and in violet shade
(c) Real, inverted, diminished and in blue shade
(d) Virtual, inverted, diminished and in blue shade

C

Question. A full length image of a distant tall building can definitely be seen by using:
(a) a concave mirror
(b) a convex mirror
(c) a plane mirror
(d) both concave as well as plane mirror

B

Question. Your school laboratory has one large window. To find the focal length of a concave mirror using one of the walls as screen, the experiment may be performed:
(a) on the same wall as the window.
(b) on the wall adjacent to the window.
(c) on the wall opposite to the window.
(d) only on the table as per laboratory arrangement.

D

Question. A student determines the focal length of a device ‘X’ by focusing the image of a distant object on a screen placed 20 cm from the device on the same side as the object.
The device ‘X’ is
(a) Concave lens of focal length 10 cm
(b) Convex lens of focal length 20 cm
(c) Concave mirror of focal length 10 cm
(d) Concave mirror of focal length 20 cm

D

Question. The path of a ray of light coming from air passing through a rectangular glass slab is traced by four students shown as A, B, C and D in the figure. Which one of them is correct?

B

Question. A student obtained a sharp inverted image of a distant tree on the screen placed behind a convex lens. He then removed the screen and tried to look through the lens in the direction of the object. He would now observe:
(a) a blurred image on the wall of the laboratory
(b) an erect image of the tree on the lens
(c) no image as the screen has been removed
(d) an inverted image of the tree at the focus of the lens

D

Question. A student determined the focal length of a device ‘X’ by focusing a bright distant object on the screen as shown in the diagram:

According to the diagram, select the correct statement from the following:
(a) Device ‘X’ is a concave mirror and distance ‘d’ is its focal length.
(b) Device ‘X’ is a concave mirror and distance ‘d’ is its radius of curvature.
(c) Device ‘X’ is a convex lens and distance ‘d’ is its focal length.
(d) Device ‘X’ is a convex lens and distance ‘d’is its radius of curvature.

C

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 the combinations for the magic mirror from top to bottom.
(a) Plane, convex and concave
(b) Convex, concave and plane
(c) Concave, plane and convex
(d) Convex, plane and concave

C

Question. In order to determine the focal length of a concave mirror by obtaining the image of a distant object on screen, the position of the screen should be:
(a) parallel to the plane of concave mirror
(b) perpendicular to the plane of concave mirror
(c) inclined at an angle 600 to the plane of mirror
(d) in any direction with respect to the plane of concave mirror

A

Question. If you focus a distant object of the shape using a concave mirror, the image obtained must be of the shape

C

Question. In which of the following diagrams has the protractor (D) been correctly placed to measure the angle of incidence and the angle of emergence?

(a) I, III
(b) I, IV
(c) II, III
(d) II, IV

A

Question. An optical device has been given to a student and he determines its focal length by focusing the image of the sun on a screen placed 24 cm from the device on the same side as the sun. Select the correct statement about the device.
(a) Convex mirror of focal length 12 cm
(b) Convex lens of focal length 24 cm
(c) Concave mirror of focal length 24 cm
(d) Convex lens of focal length 12 cm

C

Question. Select from the following the best experimental set-up for tracing the path of a ray of light through a glass slab:

(a) I
(b) II
(c) III
(d) IV

B

Question. While determining the focal length of a concave mirror, you try to focus the image of a distant object formed by the mirror on the screen. The image formed on the screen, ascompared to the object, should be:
(a) erect and highly diminished
(b) inverted and enlarged
(c) erect and enlarged
(d) inverted and highly diminished

D

Question. When you focus the image of a distant flag,whose shape is given below, on a screen using a convex lens, the shape of the image as it appears on the screen is

A

Question. The refractive index of four substance P, Q, R and S are 1.50, 1.36, 1.77 and 1.31 respectively. The speed of light is the maximum in the substance:
(a) P
(b) Q
(c) R
(d) S

D

Question. A student is performing the experiment of determining the focal length of a given concave mirror by focussing a distant tree on a screen. Which one of the following kinds of images he is likely to obtain on the screen?

(a) (A)
(b) (B)
(c) (C)
(d) (D)

B

Question. Beams of light are incident through the holes A and B and emerge out of box through the holes C and D respectively, as shown in the figure. Which of the following could be inside the box?

(a) A rectangular glass slab
(b) A convex lens
(c) A concave less
(d) A prism

A

Question. The laws of reflection hold true for:
(a) plane mirrors only
(b) concave mirrors only
(c) convex mirrors only
(d) all reflecting surfaces

D

Assertion-Reason (A-R) Questions
In each of the following questions, a statement of Assertion (A) is given followed by a corresponding statement of Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both (A) and (R) are true and (R) is the correct explanation of the (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation of the (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

Question. Assertion (A) : A convex mirror is used as a rear view/driver’s mirror.
Reasoning (R) : Convex mirrors have a wider field of view as they are curved outwards. They also give an erect, although diminished image.

Question. Assertion (A) : The word AMBULANCE on the hospital vons is written in the form of its mirror image as MA.
Reason (R) : The image formed in a plane mirror is same size of the object.

Question. Assertion (A) : Concave mirrors are used as reflectors in torches, vehicle headlights and in search lights.
Reason (R) : When an object is placed beyond the centre of curvature of a concave mirror, the image formed is real and inverted.

Question. Assertion (A) : Light travels faster in glass than in air.
Reason (R) : Glass is denser than air.

Question. Assertion (A) : Image formed by a concave lens is not always virtual.
Reason (R) : Image formed by a lens is real if the image is formed in the direction of a ray of light with respect to the lens.

Question. Assertion (A) : Assertion: A convex lens has a real focus.
Reason (R) : All light rays pass through the focus of a convex lens after refraction.

Question. Assertion (A) : A ray of light passing through the centre of curvature of a concave mirror is reflected back along the same path.
Reason (R) : The incident ray, the reflected ray and the normal at the point of incidence lie on the same plane.

Question. Assertion (A) : Power of a concave lens is negative.
Reason (R) : A concave lens has a virtual focus.

Passage Based Questions

Analyse the following observation table showing variation of image-distance (v) with object-distance (u) in case of a convex lens and answer the questions that follow without doing any calculations:

(A) What is the focal length of the convex lens? State reason for your answer.
(B) For what object-distance (u) is the corresponding image-distance (v) not correct? How did you arrive at this conclusion?
(C) A concave mirror gives real, inverted and same size image if the object is placed
(a) At focus
(b) At infinity
(c) At C i.e. centre of curvature
(d) Beyond centre of curvature
(D) Local length of plane mirror is:
(a) At infinity (b) Zero
(c) Negative (d) None of these
Answer : (A) From / S.No. 3, we can say that the radius of curvature of the lens is 20 cm because when an object is placed at the centre of curvature of a convex lens its image is
formed on the other side of the lens at the same distance from the lens. And, we also know that focal length is half of the radius of curvature. Thus, focal length of the lens is
+ 10 cm. 1
(B) S.No. 6 is not correct as for this observation the object distance is between focus and pole, and for such cases the image formed is always virtual but in this case a real image
is forming as the image distance is positive.
(C) (c) At C i.e. centre of curvature.

Question. Analyse the following table showing refractive indices of four media A, B, C and D and answer the questions that follow:
The refractive indices of four media A, B, C and D are given in the following table:

(A) If light, travels from one medium to another, in which case the change in speed will be minimum.
(B) If light, travels from one medium to another, in which case the change in speed will be maximum.
(C) A light ray enters from medium A to medium B as shown in the figure. The refractive index of medium B relative to A will be:

(a) Greater than unity
(b) Less than unity
(c) Equal to unity
(d) Zero
(D) The laws of reflection hold good for
(a) plane mirror only
(b) concave mirror only
(c) convex mirror only
(d) all mirrors irrespective of their shape
Answer : (A) Minimum change is seen as light moves between 1.50 and 1.52, i.e. B and C.
(B) Maximum change when light moves between 1.33 and 2.40, i.e. A and D.

Question: How does image changes when the face is slowly moved away from inner face of a
shining spoon?
Ans. As the face is moved away than after a particular time image becomes inverted.

Question: Identify the type of lens or mirror placed at XY where O is object and I is image.
Ans Convex lens (when object is placed between pole and focus)

Question: Due to which property of light, sharp shadow of an object is obtained?
Ans. straight line property of the light.

Question: What type of lens must be placed at XY so that image I shifts to I’

Ans. concave lens

Question:  A ray AFB is incident on a spherical mirror whose centre of curvature is 2 F. In which direction will it reflect?
Ans It will reflect towards the object side parallel to principal axis.

Question: For the same angle of incidence the angle of refraction in three different media A, B and C are 300 , 450 and 600 respectively. In which medium will the velocity of light be minimum?
Ans) μA=sin i/sin 30 , μB=sin i/sin45, μC=sin i/sin 60
μABC , μ=c/v as μA= max. ,vA=min.

Question: A ray of light is incident at angle of 350 to a plane surface. What will the angle of reflection?
Ans. 550

Question: A fish under water is viewing obliquely a fisherman standing on the bank of lake.
Does the man look taller or shorter?
Ans. As light travels from rarer to denser medium, it bends towards normal and appears
to come from greater height.. Therefore to fish under water man looks taller.

Question: Two lenses 1&2 are placed in contact .Focal length of lens 1 is 20 cm and of 2 is – 10 cm. Calculate
i) Total Power of combination
ii) What is the nature of combination..
Ans (i) P= -5 D ,(ii)Concave Lens

Question: A rod of length 10 cm lies along the principal axis of a concave mirror of f= 10 cm in such a way that the end closer to the pole is 20cm away from it. Find the length of image?
Ans. R =2f=20cm. Thus the nearer end B of the rod AB is at C and hence its image will be formed at B itself
For end A u = -30 cm, f = -10 cm, v = -15cm
Length of image will be at 5 cm

Question: An Object is placed 15 cm in front of a lens ‘A’ and lens gives real, inverted , magnified image and formed at large distance. Lens ‘A’ is replaced by Lens ‘B’ and a real, inverted image of the same size as of object is formed.
i) What is the nature of Lens A&B?
ii) What is the focal length of A&B?
Ans i) A=Convex lens ,B=Convex Lens
ii) fA=15cm, fB=7.5cm

Question: You are given three lenses.
i) a concave lens of focal length 25 cm.
ii) a convex lens of focal length ¼ m and
iii) a convex lens of focal length 100 cm.
Which combination out of these three lenses will form a lens of zero power?
Ans ) Combination of concave lens of focal length of 25 cm and a convex lens of focal length of 1/4m

Question: Absolute refractive Index of some of material is tabulated below

i) In which of these does light travel fastest and why?
ii) arrange these materials in ascending order of their optical densities.
Ans i) Water due to least refractive index.
ii) Water ,Kerosene, Rock salt ,diamond