Class 10 Science · Chapter 9

Light - Reflection and Refraction

409 Class 10 Science questions on Light - Reflection and Refraction from the NCERT textbook, NCERT Exemplar and CBSE board papers 2017–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 7 of 21

1. Q121 CBSE 2025
   An ​optical ​device ​which always ​produces images ​of $m=+1$ ​is :

   1. (a)Plane mirror
   2. (b)Convex mirror
   3. (c)Concave mirror
   4. (d)Convex lens
   Show answer

   (a) Plane mirror

   Step-by-step solution →
2. Q122 CBSE 2025
   An object is ​placed ​at ​a distance of 30 cm ​from the reflecting ​surface of ​a concave mirror of radius of curvature 40 cm. The ​image formed ​is

   1. (a)Virtual and magnified
   2. (b)Virtual and diminished
   3. (c)Real and magnified
   4. (d)Real and diminished
   Show answer

   (c) Real and magnified

   Step-by-step solution →
3. Q123 CBSE 2025
   Mirror ‘X’ is used to concentrate sunlight in ​solar furnace and Mirror ​‘Y’ is fitted on the side of the vehicle to ​see the traffic behind the driver. Which of the following ​statements are true for ​the two mirrors ?

   1. (i)The image ​formed by mirror ‘X’ is real, diminished and at its focus.
   2. (ii)​The image formed by mirror ‘Y’ is virtual, diminished and erect.
   3. (iii)The image formed ​by mirror ‘X’ is virtual, diminished and erect.
   4. (iv)The image formed by mirror ‘Y’ is real, diminished and at its focus.

   1. (a)(i) and (ii)
   2. (b)(ii) and (iii)
   3. (c)(iii) and (iv)
   4. (d)(i) and (iv)
   Show answer

   (a) (i) and (ii)

   Step-by-step solution →
4. Q124 CBSE 2025
   An optical device ​always forms ​images ​of magnification $m=+1$. This ​device ​is :

   1. (a)Concave mirror
   2. (b)Plane mirror
   3. (c)Convex lens
   4. (d)Concave lens
   Show answer

   (b) Plane mirror

   Step-by-step solution →
5. Q125 CBSE 2025
   In order to obtain large ​images ​of the teeth of patients, ​the dentist ​holds the ​concave mirror in such a ​manner that the teeth are positioned

   1. (a)at the focus of mirror.
   2. (b)between pole and focus of the mirror.
   3. (c)between focus and centre of curvature of the mirror.
   4. (d)at the centre of curvature of the mirror.
   Show answer

   (b) between pole and focus of the mirror.

   Step-by-step solution →
6. Q126 CBSE 2025
   Identify ​from ​the following the ray diagram which shows the correct path ​of the reflected ​ray for ​the ​ray incident ​on a concave mirror as shown :

   1. (a)The reflected ray crosses the principal axis between F and the pole P, and runs on below the axis.
   2. (b)The reflected ray crosses the principal axis at the centre of curvature C.
   3. (c)The reflected ray crosses the principal axis at the principal focus F.
   4. (d)The reflected ray travels back to the left above the principal axis without ever meeting it.
   Show answer

   (c) The reflected ray crosses the principal axis at the principal focus F.

   Step-by-step solution →
7. Q127 CBSE 2025
   Concave ​mirror ​finds ​its application in which ​of the following cases ​?

   1. (a)A solar furnace
   2. (b)A rear-view mirror in vehicles
   3. (c)To view full size erect image of distant tall buildings
   4. (d)To produce divergent beam of light
   Show answer

   (a) A solar furnace

   Step-by-step solution →
8. Q128 CBSE 2025
   Refractive index of diamond with ​respect ​to glass ​is $1.6$. ​If the absolute refractive index of glass is $1.5$, the absolute refractive ​index of ​diamond ​is ​:

   1. (a)$1.09$
   2. (b)$1.96$
   3. (c)$2.4$
   4. (d)$2.5$
   Show answer

   (c) $2.4$

   Step-by-step solution →
9. Q129 CBSE 2025
   Two statements ​are given — one labelled as Assertion (A) and the ​other labelled as Reason (R). ​Select the correct answer ​to this ​question ​from the codes (a), ​(b), (c) and (d) as given below.

   Assertion (A): The magnification of the virtual images produced by concave mirrors is always more than $+1$.

   Reason (R): The virtual images formed by concave mirrors are erect and magnified.

   1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
   2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
   3. (c)Assertion (A) is true, but Reason (R) is false.
   4. (d)Assertion (A) is false, but Reason (R) is true.
   Show answer

   (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

   Step-by-step solution →
10. Q130 CBSE 2025
    An object is placed at a distance of 10 cm ​in front of a concave mirror of focal length 15 cm. Use mirror formula to determine the ​position of ​the ​image formed ​by this ​mirror.
    Show answer

    $v=+30$ cm: the image is formed 30 cm behind the mirror, virtual, erect and three times the size of the object.

    $\frac{1}{v}=\frac{1}{f}-\frac{1}{u}=-\frac{1}{15}+\frac{1}{10}=\frac{1}{30}$, so $v=+30$ cm. The image is formed $30$ cm behind the mirror, on the side opposite to the object. The positive sign shows that it is a virtual image; since $m=-\frac{v}{u}=+3$, it is also erect and three times the size of the object.

    Step-by-step solution →
11. Q131 CBSE 2025
    During an experiment, a ​student observes that the given mirror is forming an ​erect and diminished image for all positions of the object ​placed in front of it. Based on the this ​information, answer the ​following ​questions :

    1. (a)Identify the mirror.
    2. (b)Using new Cartesian sign convention, write the magnitude of the magnification in this case.
    3. (c)What will be ​the radius of curvature of the mirror if its focal length is 20 ​cm ?
    Show answer

    It is a convex mirror, with $0<m<1$ and $R=40$ cm.

    (a) The mirror is a convex mirror: it is the only mirror that gives an erect, diminished image for every position of the object. (b) The magnification is positive, because the image is erect, and less than 1, because the image is diminished: $0<m<1$, so its magnitude is less than 1. For example, with $f=+20$ cm and $u=-20$ cm, $v=+10$ cm and $m=+0.5$. (c) $R=2f=2\times 20$ cm $=40$ cm; with the sign convention $R=+40$ cm, since the centre of curvature lies behind a convex mirror.

    Step-by-step solution →
12. Q132 CBSE 2025
    An ​object is ​placed at a ​distance of 30 cm in front of a concave mirror of ​focal ​length 20 cm. Use mirror formula to ​determine ​the position of ​the image formed in this case.
    Show answer

    $v=-60$ cm: the image is formed 60 cm in front of the mirror, beyond $C$, real and inverted.

    The image is formed at $v=-60$ cm, that is $60$ cm from the pole in front of the mirror, on the same side as the object and beyond the centre of curvature (at $40$ cm): $\frac{1}{v}=\frac{1}{f}-\frac{1}{u}=-\frac{1}{20}+\frac{1}{30}=-\frac{1}{60}$. The image is real and inverted ($m=-v/u=-2$).

    Step-by-step solution →
13. Q133 CBSE 2025
    When an incident ray ​of light enters a medium ‘X’ from ​air, it bends towards the normal. Infer about the ​following with respect to air :

    1. (a)Optical ​density of medium ‘X’.
    2. (b)​Speed of light through ​medium ‘X’ Give reason ​for your answer ​in each case.
    Show answer

    Medium X is optically denser than air, and light travels more slowly in X than in air.

    (a) Medium X is optically denser than air. Reason: a ray of light going from an optically rarer medium into an optically denser medium bends towards the normal, and this ray bends towards the normal on entering X from air. (b) The speed of light in medium X is less than its speed in air. Reason: light slows down on entering an optically denser medium; the refractive index of X with respect to air, $n=\frac{v_{\text{air}}}{v_X}=\frac{\sin i}{\sin r}$, is greater than $1$ because $r<i$, so $v_X<v_{\text{air}}$.

    Step-by-step solution →
14. Q134 CBSE 2025
    An object is placed at ​a distance of 60 ​cm from a ​concave lens of focal length ​30 cm. Use lens ​formula ​to find the position of ​the image ​formed in this case.
    Show answer

    $v=-20$ cm: the image is 20 cm from the lens on the same side as the object.

    $\frac{1}{v}=\frac{1}{f}+\frac{1}{u}=\frac{1}{-30}+\frac{1}{-60}=-\frac{1}{20}$, so $v=-20$ cm. The image is formed $20$ cm from the optical centre of the lens, on the same side as the object. The negative sign shows it is a virtual image; since $m=\frac{v}{u}=+\frac{1}{3}$, it is also erect and one-third the size of the object.

    Step-by-step solution →
15. Q135 CBSE 2025
    List four ​characteristics of ​the ​images ​formed ​by ​convex mirrors.
    Show answer

    The image is virtual, erect, diminished and formed between the pole and the principal focus, behind the mirror.

    For every position of the object, the image formed by a convex mirror is: (i) virtual — it lies behind the mirror and cannot be caught on a screen; (ii) erect — the same way up as the object, since $m$ is positive; (iii) diminished — always smaller than the object, since $m=f/(d+f)$ lies between $0$ and $1$; and (iv) formed between the pole and the principal focus of the mirror, since $v=fd/(d+f)$ lies between $0$ and $f$.

    Step-by-step solution →
16. Q136 CBSE 2025
    The values of absolute refractive indices of kerosene and ​water are 1.44 and 1.33 respectively. ​Compare the two media ​on the ​basis of their

    1. (a)optical density
    2. (b)mass density
    3. (c)relative speed of propagation of light. What do ​you infer ​on ​the basis of above comparisons ?
    Show answer

    Kerosene is optically denser but less dense in mass than water, and light is slower in it, so the two densities are independent.

    (a) Optical density: kerosene has the larger refractive index ($1.44>1.33$), so kerosene is optically denser than water. (b) Mass density: water is denser in mass, about $1000$ kg/m${}^3$ against about $800$ kg/m${}^3$ for kerosene, which is why kerosene floats on water. (c) Speed of light: from $v=c/n$, $v_k=2.08\times 10^8$ m/s and $v_w=2.26\times 10^8$ m/s, so light travels faster in water than in kerosene. Inference: optical density and mass density are independent properties - kerosene is optically denser yet has the smaller mass density - because optical density is decided by how much the medium slows light down and not by its mass per unit volume.

    Step-by-step solution →
17. Q137 CBSE 2025
    Study the figure in which the path of a ray ​of light going from Medium 1 to Medium 2 is shown.

    1. (a)​Out of ​the ​two Media – Medium 1 and Medium 2, in ​which is the speed ​of light more ?
    2. (b)State reason of bending of the ​refracted ray away from the normal.
    3. (c)Express refractive index of Medium 2 with respect to Medium 1 in terms of speed of light in two media.

    Show answer

    Light is faster in Medium 2; the ray bends away from the normal in the rarer medium; $n_{21}=\frac{v_1}{v_2}$.

    (a) The speed of light is more in Medium 2. (b) The ray bends away from the normal because it passes from an optically denser medium into an optically rarer medium, in which light travels faster; the change of speed at the boundary changes the direction of the ray, so the angle of refraction is greater than the angle of incidence. (c) $n_{21}=\frac{v_1}{v_2}$, where $v_1$ and $v_2$ are the speeds of light in Medium 1 and Medium 2 respectively.

    Step-by-step solution →
18. Q138 CBSE 2025
    An object is ​placed $25$ cm in front of a concave mirror of focal ​length $15$ cm. Use mirror formula and ​new ​cartesian sign ​convention to determine ​the position of ​the image formed.
    Show answer

    $v=-37.5$ cm: the image is formed 37.5 cm in front of the mirror, real, inverted and enlarged.

    $v=-37.5$ cm — the image is formed $37.5$ cm in front of the mirror, on the same side as the object. It is real, inverted and enlarged, with $m=-1.5$.

    Step-by-step solution →
19. Q139 CBSE 2025
    An object is placed $18$ cm in front of a concave mirror of ​focal length $12$ cm. Use ​mirror formula ​to ​determine the position of the image ​formed in ​this ​case.
    Show answer

    $v=-36$ cm: the image is formed 36 cm in front of the mirror, beyond $C$, real, inverted and enlarged ($m=-2$).

    $v=-36$ cm: the image is formed $36$ cm in front of the mirror, on the same side as the object, beyond the centre of curvature. It is real, inverted and enlarged, with $m=-2$.

    Step-by-step solution →
20. Q140 CBSE 2025
    Out of ​the two lenses, ​one ​concave and the other ​convex, state which one will diverge a parallel ​beam of light falling on ​it. Draw a ​ray diagram ​to show the principal focus of the lens.
    Show answer

    A concave lens diverges a parallel beam; the refracted rays appear to come from its virtual principal focus $F$.

    The concave lens diverges a parallel beam of light. After refraction the rays spread outwards, and when they are produced backwards they appear to come from a single point F on the principal axis on the same side as the incoming light. F is the principal focus of the concave lens; it is a virtual focus, so its focal length is negative.

    Step-by-step solution →