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## Class 10 Physics (India)

### Course: Class 10 Physics (India)>Unit 1

Lesson 15: Prepare for CBSE board exam

# Light class 10: CBSE previous question paper problems

Prepare for class 10 CBSE exam using this analysis of the last 10 years’ question papers from the chapter Light. Explore common and important questions, with solutions.
Let's explore problems that appeared in the last ten years of CBSE board exams, arranged by subtopic and type of question.
Happy practicing!

### Spherical mirrors

A. Definitions
Q1. Define the following terms in the context of spherical mirrors:
(start text, i, end text) Pole
(start text, i, i, end text) Center of curvature
(start text, i, i, i, end text) Principal axis
(start text, i, v, end text) Principal focus.
[2 marks, Delhi 2016]
Frequency of appearance: start color #ff9c39, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, \bigstar, end color gray
Feeling stuck?
B. Applications of spherical mirrors
Q2. Name the type of mirrors used in the following situations:
(start text, i, end text) Headlights of a car
(start text, i, i, end text) Rear-view mirror of vehicle
(start text, i, i, i, end text) Solar furnace
[5 marks, Foreign 2012]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, end color gray
Feeling stuck?
C. Drawing ray diagrams
Q3. Draw a ray diagram to show the path of the reflected ray in each of the following cases.
A ray of light incident on a convex mirror:
(start text, i, end text) strikes at its pole making an angle theta from the principal axis.
(start text, i, i, end text) is directed towards its principal focus.
(start text, i, i, i, end text) is parallel to its principal axis.
[3 marks, Foreign 2015]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, end color gray
Feeling stuck?
D. Conceptual questions about spherical mirrors
Q4. If the image formed by a mirror for all positions of the object placed in front of it is always virtual and diminished, state the type of the mirror. Draw any ray diagram in support of your answer.
[3 marks, Foreign 2016, AI 2015]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, end color gray
Feeling stuck?
• Related videos: (start text, i, end text) Concave mirrors, (start text, i, i, end text) Convex mirror & applications.
E. Inferring data from the magnification of a spherical mirror
Q5. The linear magnification produced by a spherical mirror is plus, 1, slash, 3. Analysing this value, state the (start text, i, end text) type of mirror and (start text, i, i, end text) position of the object with respect to the pole of the mirror. Draw any diagram to justify your answer.
[2 marks, AI 2014, Foreign 2014]
Frequency of appearance in CBSE exams: start color #ff9c39, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, end color gray
Q6. A spherical mirror produces a magnification of minus, 1 on a screen placed at a distance of 50, space, start text, c, m, end text from the mirror.
(start text, i, end text) Write the type of the mirror.
(start text, i, i, end text) Find the distance of the image from the object.
(start text, i, i, i, end text) What is the focal length of the mirror?
(start text, i, v, end text) Draw the ray diagram to show the image formation in this case.
[3 marks, Delhi 2014, AI 2014]
Frequency of appearance in CBSE exams: start color #ff9c39, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, end color gray
Feeling stuck?
F. Applying the magnification formula (for mirrors)
Q7. An object is kept at a distance of 4, space, start text, m, end text in front of a spherical mirror, which forms its erect image at a distance of 1, space, start text, m, end text from the mirror. What is the magnification? Is the mirror concave or convex?
[1 mark, Foreign 2010]
Frequency of appearance in CBSE exams: start color #ff9c39, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, end color gray
Similar problems: These commonly appear together with questions from the mirror formula. See the list of similar problems for Q8 below.
Here's an example of a different application of the magnification formula:
Q7.1. A concave mirror produces a three times magnified image on a screen. If the object is placed 20, space, start text, c, m, end text in front of the mirror, how far is the screen from the object?
[3 marks, Delhi 2017]
Feeling stuck?
G. Mirror formula
Q8. The image of a candle flame placed at a distance of 30, space, start text, c, m, end text from a mirror is formed on a screen placed in front of the mirror at a distance of 60, space, start text, c, m, end text from its pole. What is the nature of the mirror? Find its focal length.
[1 mark, Foreign 2010]
Frequency of appearance in CBSE exams: start color #ff9c39, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, end color gray
Feeling stuck?
H. Mirror formula plus magnification formula
Q9. Draw a diagram and apply [the new Cartesian sign] conventions for calculating focal length and nature of a spherical mirror which forms a 1, slash, 3 times magnified virtual image of an object placed 18, space, start text, c, m, end text in front of it.
[3 marks, AI 2012]
Frequency of appearance in CBSE exams: start color #ff9c39, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, \bigstar, end color gray
Feeling stuck?
I. Range of object or image distance
Q10. Suppose you want to observe an erect image of a candle flame using a concave mirror of focal length 20, space, start text, c, m, end text. State the range of distance of the candle flame from the mirror. List two other characteristics of the observed image. Draw a ray diagram to show the formation of image in this case.
[3 marks, Delhi 2013]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, end color gray

### Refraction of light and spherical lenses

A. Definitions
Q11. Explain the following terms related to spherical lenses:
(start text, i, end text) Optical centre
(start text, i, i, end text) Centres of curvature
(start text, i, i, i, end text) Principal axis
(start text, i, v, end text) Aperture
(start text, v, end text) Principal focus
(start text, v, i, end text) Focal length.
[3 marks, AI 2014]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, end color gray
Feeling stuck?
• Related videos: (start text, i, end text) Convex lenses, (start text, i, i, end text) Concave lenses.
B. Sign conventions and drawing ray diagrams
Q12. (start text, a, end text) Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.
(start text, b, end text) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (plusve or minusve as per the new Cartesian sign convention) [and state how these distances are related to the focal length (f) of the convex lens in this case].
[3 marks, Delhi 2016]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, end color gray
Feeling stuck?
C. Refraction through a glass slab
Q13. What is understood as lateral displacement of light? Illustrate this with the help of a diagram. List two factors on which the lateral displacement in a particular substance depends.
[3 marks, Foreign 2011]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, \bigstar, end color gray
Feeling stuck?
D. Refractive index, Snell's law, and the speed of light in different media
Q14. State the law of refraction of light that defines the refractive index of a medium with respect to the other. Express it mathematically. How is the refractive index of any medium 'A' with respect to a medium 'B' related to the speed of propagation of light in two media A and B? State the name of this constant when one medium is vacuum or air.
The refractive indices of glass and water with respect to vacuum are 3, slash, 2 and 4, slash, 3 respectively. If the speed of light in glass is 2, times, 10, start superscript, 8, end superscript, find the speed of light in (start text, i, end text) vacuum, (start text, i, i, end text) water.
[5 marks, Delhi 2012]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, \bigstar, \bigstar, end color #ff9c39
Feeling stuck?
E. Conceptual questions about spherical lenses
Q15. One student uses a lens of focal length plus, 50, space, start text, c, m, end text and another of minus, 50, space, start text, c, m, end text. State the nature and find the power of each lens. Which of the two lenses will always give a virtual and diminished image irrespective of the position of the object?
[3 marks, Foreign 2014]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, end color gray
F. Lens formula plus magnification formula
Q16. The image of a candle flame placed at a distance of 30, space, start text, c, m, end text from a spherical lens is formed on a screen placed on the other side of the lens at a distance of 60, space, start text, c, m, end text from the optical centre of the lens. Identify the type of lens and calculate its focal length. If the height of the flame is 3, space, start text, c, m, end text, find the height of the image.
[5 marks, Delhi 2015]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, \bigstar, \bigstar, end color #ff9c39
Feeling stuck?
G. Power of lens
Q17. Find the power of a convex lens which forms a real and inverted image of magnification minus, 1 of an object placed at a distance of 20, space, start text, c, m, end text from its optical centre.
[2 marks, Delhi 2016]
Frequency of appearance: start color #ff9c39, \bigstar, \bigstar, \bigstar, end color #ff9c39, start color gray, \bigstar, \bigstar, end color gray
Feeling stuck?

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