Looking for reliable SEBA Class 10 Science Chapter 10 (Light – Reflection and Refraction) extra questions and answers for the 2026–27 academic year? Access essential numerical practice problems, mirror and lens formula practice sets, ray diagram construction questions, refractive index numericals, and conceptual physics notes to score top marks in your HSLC board exams.
EXTRA QUESTION AND ANSWER
Q1. Define light and explain why we cannot see objects in the dark.
Ans.
Light is a form of energy that enables us to see objects. We can see an object only when light reflected from its surface enters our eyes. In darkness, no light is available for reflection, so objects cannot be seen.
Q2. State two properties of light.
Ans.
- Light travels in a straight line (rectilinear propagation).
- Light can be reflected and refracted when it strikes surfaces or enters different media.
Q3. What is reflection of light? State its laws.
Ans.
Reflection is the bouncing back of light when it strikes a polished surface like a mirror.
Laws of Reflection:
- The angle of incidence (∠i) is equal to the angle of reflection (∠r).
- The incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane.
Q4. What type of image is formed by a plane mirror?
Ans.
The image formed by a plane mirror is:
- Virtual and erect
- Same size as the object
- Laterally inverted (left-right reversed)
- Formed behind the mirror at the same distance as the object in front
Q5. Distinguish between concave and convex mirrors.
Ans.
| Feature | Concave Mirror | Convex Mirror |
| Reflecting Surface | Curved inward | Curved outward |
| Action on Light | Converges light rays | Diverges light rays |
| Image Formed | Real and inverted (Virtual and erect when object is between P and F) | Always virtual, erect, and diminished |
| Common Uses | Torches, dentist mirrors, shaving mirrors | Rear-view mirrors in vehicles |
SEBA Class 10 Science Chapter 10 Extra Questions
Q6. Define pole, centre of curvature, and principal axis.
Ans.
- Pole (P): The centre of the reflecting surface of a spherical mirror.
- Centre of Curvature (C): The centre of the sphere of which the mirror forms a part.
- Principal Axis: The straight line passing through the pole (P) and the centre of curvature (C).
Q7. What is the relation between focal length and radius of curvature?
Ans.
The focal length (f) of a spherical mirror is equal to half of its radius of curvature (R):
R = 2f (or f = R / 2)
Q8. What kind of image does a concave mirror form when the object is placed between focus (F) and pole (P)?
Ans.
The image formed is virtual, erect, enlarged, and appears behind the mirror (e.g., as used in a shaving mirror).
Q9. State two uses of concave mirrors.
Ans.
- Used in torches, searchlights, and vehicle headlights to produce powerful parallel beams of light.
- Used by dentists and as shaving mirrors to see an enlarged image of the object.
Q10. What type of image is formed by a convex mirror? Give one use.
Ans.
A convex mirror always forms a virtual, erect, and diminished image.
Use: It is used as a rear-view mirror in vehicles because it provides a wider field of view to the driver.
Class 10 Science Chapter 10 Important Questions SEBA 2026-27
Q11. State the mirror formula and define each term.
Ans.
The mirror formula is:
1/f = 1/v + 1/u
Where:
- f = focal length of the mirror
- v = image distance from pole
- u = object distance from pole
Q12. Define magnification for mirrors and give its formula.
Ans.
Magnification (m) is the ratio of the height of the image to the height of the object.
m = height of image / height of object = -v / u
- If m is positive, the image is virtual and erect.
- If m is negative, the image is real and inverted.
Q13. What is refraction of light? Give one example.
Ans.
Refraction is the bending of light when it passes obliquely from one transparent medium to another due to a change in its speed.
Example: A pencil partially immersed in water appears bent at the water surface.
Q14. State the laws of refraction (Snell’s laws).
Ans.
- The incident ray, the refracted ray, and the normal to the interface at the point of incidence all lie in the same plane.
- The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for a given pair of media:
sin i / sin r = constant (Snell’s Law)
Q15. Define refractive index.
Ans.
Refractive index (n) of a medium is the ratio of the speed of light in vacuum (or air) to the speed of light in that medium:
n = c / v
It indicates the degree of bending or optical density of a medium.
Light Reflection and Refraction Class 10 SEBA Extra Question Answer
Q16. What is optical density?
Ans.
Optical density measures how much a medium slows down light. A medium with a higher refractive index is optically denser. Light bends towards the normal when entering an optically denser medium.
Q17. Define a lens and list its two types.
Ans.
A lens is a transparent material bounded by two surfaces, of which one or both are spherical.
Types:
- Convex lens: Converging lens (thicker at the middle, thinner at the edges).
- Concave lens: Diverging lens (thinner at the middle, thicker at the edges).
Q18. What is the optical centre of a lens?
Ans.
The optical centre (O) is the central point of a lens through which a ray of light passes without undergoing any deviation.
Q19. What is the principal focus of a convex and a concave lens?
Ans.
- Convex Lens: The point on the principal axis where rays of light parallel to the principal axis converge after refraction.
- Concave Lens: The point on the principal axis from which rays of light parallel to the principal axis appear to diverge after refraction.
Q20. State the sign convention used for lenses.
Ans.
- Distances measured in the direction of incident light (to the right of optical centre) are taken as positive (+ve).
- Distances measured opposite to incident light (to the left of optical centre) are taken as negative (-ve).
- Heights measured upward perpendicular to principal axis are positive (+ve); downward are negative (-ve).
- Focal Length: Convex lens = positive (+ve); Concave lens = negative (-ve).
SEBA Class 10 Science Chapter 10 Numericals
Q21. Write the lens formula and define the terms.
Ans.
The lens formula is:
1/f = 1/v – 1/u
Where:
- f = focal length of the lens
- v = image distance from optical centre
- u = object distance from optical centre
Q22. Define magnification for a lens. Give its formula.
Ans.
Magnification (m) is the ratio of the height of the image to the height of the object.
m = height of image / height of object = v / u
- If m is positive (+ve), the image is erect and virtual.
- If m is negative (-ve), the image is inverted and real.
Q23. What is the power of a lens? State its unit.
Ans.
Power (P) of a lens is the degree of convergence or divergence of light rays achieved by it, defined as the reciprocal of its focal length in metres.
P = 1 / f (in metres)
Unit: Dioptre (D), where 1 D = 1 m⁻¹.
Q24. What is the power of a convex lens of focal length 0.5 m?
Ans.
f = +0.5 m
P = 1 / f = 1 / (+0.5) = +2 D
Power = +2 Dioptres.
Q25. What is the power of a concave lens of focal length 0.4 m?
Ans.
f = -0.4 m
P = 1 / f = 1 / (-0.4) = -2.5 D
Power = -2.5 Dioptres.
HSLC Science Light Important Questions
Q26. What happens when two lenses are placed in contact?
Ans.
When lenses are placed in contact, their powers add up algebraically:
P = P1 + P2 + P3 + …
(Example: If P1 = +2 D and P2 = +1 D, total power P = +2 + 1 = +3 D).
Q27. Give two uses each of convex and concave lenses.
Ans.
- Convex Lens: Used in magnifying glasses, cameras, and microscopes.
- Concave Lens: Used in spectacles to correct myopia (short-sightedness), peepholes in doors, and flashlights.
Q28. Why does a convex lens burn paper when kept in sunlight?
Ans.
A convex lens converges parallel rays of sunlight passing through it to a single point at its principal focus. This concentrates a intense amount of heat energy at that focal spot, raising the temperature enough to burn the paper.
Q29. State two differences between reflection and refraction.
Ans.
| Feature | Reflection | Refraction |
| Mechanism | Light bounces back into the same medium | Light bends and passes into a different medium |
| Surface/Boundary | Occurs on polished/opaque surfaces (e.g., mirror) | Occurs at the transparent boundary between two media |
Q30. Why are convex mirrors preferred as rear-view mirrors?
Ans.
Convex mirrors always produce virtual, erect, and diminished images of objects behind the vehicle, providing a much wider field of view than a plane mirror can offer.
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