MCQ Question practice
1. What makes things visible?
a) Darkness
b) Light
c) Sound
d) Air
✔️ Answer: b) Light
2. Light travels in a _______.
a) Circular path
b) Zig-zag path
c) Straight line
d) Curved line
✔️ Answer: c) Straight line
3. The bouncing back of light from a surface is called:
a) Refraction
b) Dispersion
c) Reflection
d) Absorption
✔️ Answer: c) Reflection
4. Which device is used to see objects behind you in vehicles?
a) Concave lens
b) Plane mirror
c) Convex mirror
d) Prism
✔️ Answer: c) Convex mirror
5. An image that cannot be obtained on a screen is called:
a) Real
b) Virtual
c) Inverted
d) Enlarged
✔️ Answer: b) Virtual
6. The image formed by a plane mirror is:
a) Real and inverted
b) Virtual and inverted
c) Real and erect
d) Virtual and erect
✔️ Answer: d) Virtual and erect
7. The mirror used by dentists to view teeth is a:
a) Plane mirror
b) Convex mirror
c) Concave mirror
d) Cylindrical mirror
✔️ Answer: c) Concave mirror
8. The image formed in a plane mirror is:
a) Laterally inverted
b) Magnified
c) Inverted
d) Smaller than the object
✔️ Answer: a) Laterally inverted
9. The angle between the incident ray and the normal is called:
a) Angle of refraction
b) Angle of deviation
c) Angle of incidence
d) Angle of emergence
✔️ Answer: c) Angle of incidence
10. Which mirror is used in torchlights?
a) Plane mirror
b) Convex mirror
c) Concave mirror
d) Parabolic mirror
✔️ Answer: c) Concave mirror
11. A ray of light falling on a surface is called:
a) Incident ray
b) Reflected ray
c) Normal ray
d) Divergent ray
✔️ Answer: a) Incident ray
12. The line perpendicular to the reflecting surface is called:
a) Angle
b) Axis
c) Normal
d) Vertex
✔️ Answer: c) Normal
13. Light travels at a speed of approximately:
a) 300 m/s
b) 3,000 m/s
c) 30,000 km/s
d) 3 × 10⁸ m/s
✔️ Answer: d) 3 × 10⁸ m/s
14. Which part of the eye controls the amount of light entering it?
a) Retina
b) Cornea
c) Iris
d) Optic nerve
✔️ Answer: c) Iris
15. The image formed on the retina is:
a) Virtual and erect
b) Real and inverted
c) Virtual and inverted
d) Real and erect
✔️ Answer: b) Real and inverted
16. The smallest part of the eye through which light enters is:
a) Retina
b) Iris
c) Pupil
d) Cornea
✔️ Answer: c) Pupil
17. Which of the following is a luminous object?
a) Book
b) Moon
c) Bulb
d) Chair
✔️ Answer: c) Bulb
18. The distance between the pole and focus is called:
a) Radius
b) Focal length
c) Aperture
d) Diameter
✔️ Answer: b) Focal length
19. The mirror that always forms a diminished image is:
a) Concave mirror
b) Convex mirror
c) Plane mirror
d) None
✔️ Answer: b) Convex mirror
20. The image of an object placed at infinity by a concave mirror is formed at:
a) At focus, real and inverted
b) At center, virtual and erect
c) At pole, real
d) Behind the mirror
✔️ Answer: a) At focus, real and inverted
21. Which type of image can be formed on a screen?
a) Real
b) Virtual
c) Lateral
d) Erect
✔️ Answer: a) Real
22. Which is a non-luminous object?
a) Sun
b) Star
c) Bulb
d) Moon
✔️ Answer: d) Moon
23. The straight line joining the pole and center of curvature is called:
a) Mirror line
b) Principal axis
c) Reflection line
d) Tangent
✔️ Answer: b) Principal axis
24. Which of the following mirrors is used in shaving mirrors?
a) Convex
b) Plane
c) Concave
d) Cylindrical
✔️ Answer: c) Concave
25. A mirror forms an image of the same size as the object. The mirror is:
a) Convex
b) Plane
c) Concave
d) Parabolic
✔️ Answer: b) Plane
26. Which phenomenon is responsible for forming shadows?
a) Diffusion
b) Reflection
c) Refraction
d) Rectilinear propagation
✔️ Answer: d) Rectilinear propagation
27. A mirror that diverges rays of light falling on it is called:
a) Plane mirror
b) Concave mirror
c) Convex mirror
d) Cylindrical mirror
✔️ Answer: c) Convex mirror
28. Which mirror is best suited for security purposes in shops?
a) Plane
b) Concave
c) Convex
d) None
✔️ Answer: c) Convex
29. Reflection of light from a smooth surface is called:
a) Regular reflection
b) Diffused reflection
c) Dispersed reflection
d) Irregular reflection
✔️ Answer: a) Regular reflection
30. The mirror that can form both real and virtual images is:
a) Plane
b) Convex
c) Concave
d) None
✔️ Answer: c) Concave
31. What type of image is formed by a convex mirror?
a) Real and inverted
b) Virtual and erect
c) Real and erect
d) Virtual and inverted
✔️ Answer: b) Virtual and erect
32. Light changes direction when it passes through a:
a) Mirror
b) Prism
c) Vacuum
d) Transparent medium
✔️ Answer: d) Transparent medium
33. Which is not a source of light?
a) Sun
b) Firefly
c) Mirror
d) Candle
✔️ Answer: c) Mirror
34. The phenomenon of bending of light when it passes from one medium to another is called:
a) Reflection
b) Refraction
c) Dispersion
d) Diffraction
✔️ Answer: b) Refraction
35. Which of these objects forms a shadow?
a) Transparent
b) Opaque
c) Translucent
d) Luminous
✔️ Answer: b) Opaque
36. If the angle of incidence is 40°, what is the angle of reflection?
a) 40°
b) 50°
c) 90°
d) 20°
✔️ Answer: a) 40°
37. Which type of mirror is used in street lights?
a) Concave mirror
b) Convex mirror
c) Plane mirror
d) Cylindrical mirror
✔️ Answer: b) Convex mirror
38. The retina is sensitive to:
a) Touch
b) Smell
c) Sound
d) Light
✔️ Answer: d) Light
39. Which mirror forms a real image?
a) Plane
b) Convex
c) Concave
d) All
✔️ Answer: c) Concave
40. The full form of IRIS in the eye is:
a) It is not an abbreviation
b) Infra Red Imaging Sensor
c) Internal Retinal Image Setup
d) Inner Retina Imaging System
✔️ Answer: a) It is not an abbreviation
41. The eye lens forms the image on the:
a) Cornea
b) Iris
c) Retina
d) Pupil
✔️ Answer: c) Retina
42. Which part of the eye sends signals to the brain?
a) Cornea
b) Retina
c) Iris
d) Optic nerve
✔️ Answer: d) Optic nerve
43. What is the nature of the image formed by a convex mirror?
a) Real, diminished
b) Virtual, erect, diminished
c) Virtual, magnified
d) Real, erect, magnified
✔️ Answer: b) Virtual, erect, diminished
44. Which of the following cannot form a real image?
a) Concave mirror
b) Convex mirror
c) Plane mirror
d) Both b and c
✔️ Answer: d) Both b and c
45. Image formed by our eyes is:
a) Real and inverted
b) Virtual and erect
c) Real and erect
d) Virtual and inverted
✔️ Answer: a) Real and inverted
46. Which mirror is used in solar cookers?
a) Plane
b) Convex
c) Concave
d) None
✔️ Answer: c) Concave
47. When light falls on a mirror at 30°, the reflected ray will be at:
a) 30°
b) 60°
c) 90°
d) 0°
✔️ Answer: a) 30°
48. Which of the following materials is transparent?
a) Wood
b) Glass
c) Cardboard
d) Mirror
✔️ Answer: b) Glass
49. A beam of light is a:
a) Single ray
b) Bundle of light rays
c) Source of light
d) Image of light
✔️ Answer: b) Bundle of light rays
50. Which surface gives a regular reflection?
a) Rough wall
b) Sandpaper
c) Polished table
d) Rocky surface
✔️ Answer: c) Polished table
90. Plane mirror produces how many images of an object?
a) One
b) Two
c) Many
d) None
✔️ Answer: a) One
91. Which of the following mirrors can form an enlarged image?
a) Plane
b) Convex
c) Concave
d) Both b and c
✔️ Answer: c) Concave
92. Which part of the eye allows vision in dim light?
a) Cones
b) Rods
c) Cornea
d) Retina
✔️ Answer: b) Rods
93. Which part of the eye helps in color perception?
a) Rods
b) Cones
c) Iris
d) Lens
✔️ Answer: b) Cones
94. What is the nature of the image formed by the retina?
a) Real and inverted
b) Virtual and inverted
c) Virtual and erect
d) Real and erect
✔️ Answer: a) Real and inverted
95. The inability to distinguish colors is called:
a) Cataract
b) Blindness
c) Color blindness
d) Astigmatism
✔️ Answer: c) Color blindness
96. The point through which the light ray passes undeviated is called:
a) Pole
b) Focus
c) Optical center
d) Radius
✔️ Answer: c) Optical center
97. When light passes through a prism, the light splits into:
a) 5 colors
b) 6 colors
c) 7 colors
d) Infinite colors
✔️ Answer: c) 7 colors
98. Which color appears at the top of the rainbow?
a) Violet
b) Red
c) Blue
d) Green
✔️ Answer: b) Red
99. Which color is at the bottom of the rainbow?
a) Red
b) Violet
c) Orange
d) Green
✔️ Answer: b) Violet
100. Which device uses total internal reflection to work?
a) Prism
b) Optical fiber
c) Lens
d) Mirror
✔️ Answer: b) Optical fiber
✅ Very Short Answer Questions (with Answers)
Class 8 – Science – Light
1. What is light?
→ Light is a form of energy that enables us to see objects.
2. In which path does light travel?
→ Straight line.
3. What is the bouncing back of light called?
→ Reflection.
4. What is a ray of light?
→ A straight line path along which light travels.
5. What is a beam of light?
→ A group of light rays.
6. Name the device that helps us to see behind in vehicles.
→ Convex mirror.
7. What is lateral inversion?
→ The left appears right and right appears left in a mirror.
8. What kind of image is formed by a plane mirror?
→ Virtual and erect.
9. What kind of mirror is used by dentists?
→ Concave mirror.
10. Define real image.
→ An image that can be obtained on a screen.
11. Define virtual image.
→ An image that cannot be obtained on a screen.
12. Which mirror always forms a virtual image?
→ Plane mirror.
13. What is the angle between incident ray and normal called?
→ Angle of incidence.
14. What is the angle between reflected ray and normal called?
→ Angle of reflection.
15. Name a mirror that always forms a diminished image.
→ Convex mirror.
16. Which law states that angle of incidence equals angle of reflection?
→ Law of reflection.
17. What is the center of a spherical mirror called?
→ Center of curvature.
18. What is the mid-point of the mirror’s surface called?
→ Pole.
19. What is the distance between pole and focus called?
→ Focal length.
20. What is the distance between pole and center of curvature?
→ Radius of curvature.
21. Which mirror converges rays of light?
→ Concave mirror.
22. Which mirror diverges rays of light?
→ Convex mirror.
23. What type of image is formed by a concave mirror when object is close?
→ Virtual and enlarged.
24. Which mirror is used in solar cookers?
→ Concave mirror.
25. What is the nature of the image formed by a convex mirror?
→ Virtual, erect, and diminished.
26. What is the function of the retina?
→ To form an image.
27. Which part of the eye controls light entry?
→ Iris.
28. What is the black opening in the center of the eye called?
→ Pupil.
29. Which nerve sends image signals to the brain?
→ Optic nerve.
30. Which cells help in seeing in dim light?
→ Rods.
31. Which cells help in seeing colors?
→ Cones.
32. What is the function of the cornea?
→ To refract light entering the eye.
33. What is the role of the lens in the eye?
→ Focus light on the retina.
34. Name the condition where a person can’t see nearby objects clearly.
→ Hypermetropia.
35. Which lens is used to correct myopia?
→ Concave lens.
36. Which lens is used to correct hypermetropia?
→ Convex lens.
37. What is dispersion of light?
→ Splitting of light into its colors.
38. How many colors are in a rainbow?
→ Seven.
39. What causes a rainbow?
→ Dispersion and reflection of sunlight by raindrops.
40. What is total internal reflection?
→ Complete reflection of light within a medium.
41. What is the full form of IRIS in eye?
→ It is not an acronym.
42. What type of reflection occurs on smooth surfaces?
→ Regular reflection.
43. What type of reflection occurs on rough surfaces?
→ Diffused reflection.
44. What kind of image does a convex mirror form?
→ Virtual and diminished.
45. What is the shape of a concave mirror?
→ Spherical and inward curved.
46. What is the shape of a convex mirror?
→ Spherical and outward curved.
47. Which part of the eye is transparent and bulges out?
→ Cornea.
48. What is the size of the image in a plane mirror?
→ Same as object.
49. What happens to light when it passes from air to glass?
→ It bends (refracts).
50. What is the rule for reflection in plane mirrors?
→ Angle of incidence = angle of reflection.
1. What is reflection of light?
Reflection is the bouncing back of light from a polished or shiny surface like a mirror.
2. State the two laws of reflection.
-
Angle of incidence = Angle of reflection
-
The incident ray, reflected ray, and normal lie in the same plane.
3. What is the difference between regular and diffused reflection?
Regular reflection occurs on smooth surfaces and produces clear images, while diffused reflection occurs on rough surfaces and forms no clear image.
4. What do we mean by a virtual image?
A virtual image is one that cannot be formed on a screen. It appears to be behind the mirror.
5. What is meant by lateral inversion?
Lateral inversion is the phenomenon where the left and right sides appear reversed in a mirror image.
6. Name the types of mirrors.
Plane mirror, Concave mirror, and Convex mirror.
7. What is a concave mirror?
A concave mirror is a spherical mirror whose reflecting surface is curved inward.
8. What is a convex mirror?
A convex mirror is a spherical mirror whose reflecting surface is curved outward.
9. Define pole, focus, and center of curvature of a spherical mirror.
-
Pole: The center of the mirror’s surface
-
Focus: Point where parallel rays converge or appear to diverge
-
Center of curvature: The center of the sphere of which the mirror is a part
10. What kind of image is formed by a concave mirror when the object is placed between pole and focus?
A virtual, erect, and enlarged image is formed.
11. What kind of image is formed by a convex mirror?
Virtual, erect, and diminished image.
12. Why are concave mirrors used in headlights?
Because they converge light rays and produce a strong parallel beam.
13. Why are convex mirrors used in vehicles?
Because they provide a wider field of view.
14. What is refraction of light?
Refraction is the bending of light when it passes from one medium to another.
15. Why does light bend during refraction?
Because it changes speed when moving from one medium to another.
16. Define real image.
A real image is one that can be obtained on a screen and is usually inverted.
17. Define focal length.
The distance between the pole and the focus of a spherical mirror.
18. What is the nature of the image formed by a plane mirror?
Virtual, erect, same size, and laterally inverted.
19. What is dispersion of light?
The splitting of white light into its seven component colors.
20. Name the colors of the visible spectrum.
Violet, Indigo, Blue, Green, Yellow, Orange, Red (VIBGYOR)
21. What is the role of the iris in the human eye?
The iris controls the size of the pupil and the amount of light entering the eye.
22. What is the retina?
Retina is the light-sensitive screen in the eye where images are formed.
23. What are rods and cones?
Rods detect dim light; cones detect color.
24. Why does a shadow form?
A shadow forms when an opaque object blocks light.
25. What is a pinhole camera?
A device that forms an image by allowing light to pass through a tiny hole.
26. Why does a concave mirror form different types of images?
Because image formation varies with the position of the object.
27. What is meant by the principal axis?
A straight line passing through the pole and center of curvature of a mirror.
28. What is the significance of the center of curvature?
It is the center of the sphere from which the mirror segment is taken.
29. What happens when an object is at the focus of a concave mirror?
Image is formed at infinity and highly enlarged.
30. How can you show that light travels in a straight line?
By using a pinhole camera or looking through aligned holes in cardboard.
31. How does a rainbow form?
By dispersion, reflection, and refraction of sunlight by raindrops.
32. What is total internal reflection?
When light reflects completely inside a denser medium at a certain angle.
33. What is the blind spot in the eye?
It is the point on the retina where the optic nerve exits and no image is formed.
34. What causes twinkling of stars?
Due to refraction of starlight by Earth's atmosphere.
35. How is a concave mirror used in solar cookers?
It focuses sunlight at one point to produce heat.
36. What is the nature of the image formed by the eye lens?
Real and inverted.
37. What are luminous objects?
Objects that emit their own light (e.g. Sun, bulb).
38. What are non-luminous objects?
Objects that do not emit light but reflect it (e.g. Moon, book).
39. What is an optical instrument?
A device that uses lenses or mirrors to form images (e.g. camera, telescope).
40. What happens to the size of the image in a concave mirror as the object moves closer?
The image becomes larger and more magnified.
41. Why can't a convex mirror form a real image?
Because the reflected rays diverge and do not actually meet.
42. Why does a pencil appear bent in water?
Due to refraction of light at the interface of air and water.
43. Why is the Sun visible a few minutes before actual sunrise?
Due to atmospheric refraction bending sunlight.
44. What is meant by inverted image?
An image that appears upside down compared to the object.
45. What is meant by erect image?
An image that appears upright as the object.
46. Why are mirrors polished?
To reflect light effectively.
47. What is the function of the pupil?
To allow light to enter the eye.
48. What is magnification?
The ratio of the size of the image to the size of the object.
49. What is the normal in reflection?
A perpendicular line drawn to the surface at the point of incidence.
50. Why can’t we see in total darkness?
Because light is required for vision.
51. What is meant by image formation?
When reflected or refracted rays appear to meet, an image is formed.
52. What is the main use of rearview mirrors?
To see the traffic behind the vehicle.
53. How many images are formed when two mirrors are placed at 90°?
Three images.
54. Why is the image in a mirror not real?
Because the rays do not actually meet; they only appear to.
55. Why is a convex mirror preferred for security purposes?
It provides a wide-angle view.
56. What is the relation between focal length and radius of curvature?
f = R / 2
57. What is the mirror formula?
1/f = 1/v + 1/u (used in higher classes, conceptually important)
58. Why are shadows black?
Because no light reaches the region behind the object.
59. Can a mirror form a magnified virtual image?
Yes, a concave mirror can do that when the object is close to it.
60. What is a real-life use of plane mirrors besides reflection?
Periscopes, kaleidoscopes, dressing mirrors.
📝 Long Answer Questions (With Answers)
1. Explain the laws of reflection of light with the help of a diagram.
Answer:
There are two laws of reflection:
-
The angle of incidence is equal to the angle of reflection.
-
The incident ray, reflected ray, and the normal all lie in the same plane.
Diagram: (Draw a ray hitting a mirror, with angles labeled.)
2. Differentiate between real and virtual images with examples.
Answer:
-
Real Image: Formed when reflected rays actually meet; can be obtained on a screen. Example: Image formed by a concave mirror when the object is beyond the focus.
-
Virtual Image: Formed when reflected rays appear to meet; cannot be obtained on a screen. Example: Image in a plane mirror.
3. Describe image formation by a concave mirror for various positions of the object.
Answer:
| Object Position | Image Formed |
|---|---|
| At infinity | Real, inverted, highly diminished at F |
| Beyond C | Real, inverted, smaller, between F and C |
| At C | Real, inverted, same size at C |
| Between C and F | Real, inverted, enlarged beyond C |
| At F | Image at infinity |
| Between F and Pole | Virtual, erect, enlarged behind mirror |
4. What is dispersion of light? Describe how a rainbow is formed.
Answer:
Dispersion is the splitting of white light into seven colors.
Rainbow Formation:
-
Sunlight enters raindrops, gets refracted, then internally reflected and dispersed.
-
This results in seven colors appearing in the sky in the form of a rainbow.
5. Describe the structure and function of the human eye.
Answer:
Parts and Functions:
-
Cornea: Transparent outer layer, allows light to enter.
-
Pupil: Opening that controls light entry.
-
Iris: Colored part, adjusts pupil size.
-
Lens: Focuses light on retina.
-
Retina: Light-sensitive screen, forms real image.
-
Optic Nerve: Sends signals to brain.
The eye helps in vision by adjusting focus and processing light into images.
6. What is a plane mirror? Explain its image characteristics.
Answer:
A plane mirror is a flat, polished surface that reflects light.
Image characteristics:
-
Virtual and erect
-
Laterally inverted
-
Same size as the object
-
Image is as far behind the mirror as the object is in front
7. Explain why a concave mirror is used in solar cookers.
Answer:
A concave mirror converges parallel rays of sunlight to a point (focus), concentrating heat.
This high temperature helps cook food quickly. The concave shape is ideal for focusing energy.
8. How do convex mirrors help in road safety?
Answer:
Convex mirrors provide a wide field of view as they diverge light rays.
They form virtual, erect, and diminished images, allowing drivers to see more area, helping avoid collisions and increasing safety.
9. Compare the image formation of concave and convex mirrors.
Answer:
| Mirror Type | Image Nature | Size | Position | Real/Virtual |
|---|---|---|---|---|
| Concave | Erect/Inverted | Enlarged/Diminished | In front of mirror | Both |
| Convex | Always Erect | Always Diminished | Behind mirror | Virtual |
10. What are the differences between regular and diffused reflection? Give examples.
Answer:
-
Regular Reflection: From smooth surfaces like a mirror. Image is formed.
-
Diffused Reflection: From rough surfaces like paper. No clear image.
Example: Mirror vs. wall.
11. Describe the process of image formation in the human eye.
Answer:
Light enters through the cornea, passes through the aqueous humour, then through the pupil. The iris adjusts the pupil based on light. The lens focuses the image on the retina, which converts it to electrical signals. These signals travel through the optic nerve to the brain.
12. Explain how a periscope works.
Answer:
A periscope uses two plane mirrors placed at 45° angles inside a tube.
Light reflects from one mirror to another, allowing us to see over walls or around corners. Used in submarines and trenches.
13. What are the characteristics of the image formed by a convex mirror?
Answer:
-
Always virtual and erect
-
Always diminished
-
Formed behind the mirror
-
Used for wide field viewing
14. How does a pinhole camera work?
Answer:
A pinhole camera allows light through a tiny hole onto a screen.
An inverted, real, and diminished image is formed on the screen. It works on the principle that light travels in straight lines.
15. Explain why we cannot see clearly in dim light.
Answer:
In dim light, the rods in our retina work, but they are less sensitive to detail and color. Cones, which detect color and sharp images, do not function well in low light.
16. Discuss the use of mirrors in daily life with examples.
Answer:
-
Plane mirrors: Dressing, bathrooms
-
Concave mirrors: Makeup mirrors, dentist tools, headlights
-
Convex mirrors: Vehicle side mirrors, surveillance
Mirrors help us see images, improve safety, and reflect light.
17. How does the eye adjust to different light conditions?
Answer:
The iris controls the size of the pupil.
-
In bright light: Pupil contracts to reduce light.
-
In dim light: Pupil expands to allow more light.
This helps protect the eye and ensure clear vision.
18. What is lateral inversion? How does it happen?
Answer:
Lateral inversion is the left-right reversal in mirror images.
It happens because the mirror reflects light directly back, but our brain assumes light travels in a straight line.
19. Write the rules of image formation by concave mirrors.
Answer:
-
A ray parallel to principal axis passes through focus.
-
A ray through the center of curvature reflects back on the same path.
-
A ray passing through the focus reflects parallel to principal axis.
-
A ray hitting the pole reflects at equal angle.
20. Write the rules of image formation by convex mirrors.
Answer:
-
A ray parallel to the principal axis appears to come from the focus.
-
A ray heading toward the center of curvature reflects back on the same path.
-
All reflected rays diverge, and appear to meet at a point behind the mirror.
21. Explain the image formation by a concave mirror when the object is placed at different positions.
(Already covered in Q3; can be redrawn and elaborated)
22. How is a shadow formed? Explain its properties.
Answer:
A shadow is formed when an opaque object blocks light.
Properties:
-
Dark in center (umbra), light at edges (penumbra)
-
Size depends on distance of object and light
-
Only forms with a light source and opaque object
23. Describe the structure and functioning of an optical fibre.
Answer:
Optical fibres are thin glass strands that use total internal reflection.
Light enters at one end and reflects inside repeatedly until it exits at the other.
Used in internet cables, medical devices.
24. Explain why white light splits into colors when it passes through a prism.
Answer:
Because different colors bend (refract) by different amounts, with violet bending the most and red the least. This is called dispersion.
25. Why do stars twinkle but planets don’t?
Answer:
Stars are very far, and their light gets bent by atmospheric refraction causing twinkling.
Planets appear steady as their light appears to come from a wider source.
26. How does a kaleidoscope work?
Answer:
It uses three plane mirrors arranged in a triangle. Colored objects placed inside produce multiple reflections forming symmetrical patterns.
27. Why is vision not clear underwater without goggles?
Answer:
Because water and cornea have similar refractive indices, bending of light doesn’t occur properly, so the image doesn’t focus well on the retina.
28. How do sunglasses protect the eyes?
Answer:
They block harmful UV rays and reduce glare. Some have polarized lenses to cut out horizontal light reflections.
29. What is total internal reflection? State two applications.
Answer:
When light travels from denser to rarer medium and hits the boundary at a steep angle, it reflects entirely within the medium.
Applications:
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Optical fibres
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Diamond sparkle
30. Why is concave mirror used by ENT specialists?
Answer:
It focuses light on specific body parts and forms a magnified image for examination.
31. What causes color blindness?
Answer:
It is caused by the absence or defect of cone cells in the retina that sense specific colors. It is often inherited genetically.
32. How do rods and cones function in the eye?
Answer:
-
Rods: Help in night/dim vision, detect shades of grey
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Cones: Help in daylight and color vision
33. Explain how magnification occurs in concave mirrors.
Answer:
When the object is close to the mirror (between focus and pole), the reflected rays diverge and appear to come from a larger image behind the mirror.
34. Describe the working of a lens in the eye.
Answer:
The convex lens in the eye bends light rays and focuses them on the retina.
It adjusts shape to focus near and far objects (accommodation).
35. What is the blind spot and why is it called so?
Answer:
It is the point on the retina where the optic nerve exits. No rods or cones are present, so no image is formed — hence “blind”.
36. How does a convex lens help correct hypermetropia?
Answer:
In hypermetropia (farsightedness), the image forms behind the retina. A convex lens bends light to converge sooner, forming the image on the retina.
37. Why is rearview mirror always a convex mirror?
Answer:
Because it gives a wide field of view and shows a larger area behind the vehicle, though images are smaller.
38. How does light behave when it passes from air to water?
Answer:
It slows down and bends towards the normal due to higher density of water — this is refraction.
39. What is the difference between incident ray and reflected ray?
Answer:
-
Incident Ray: The ray striking the surface
-
Reflected Ray: The ray bouncing off from the surface
40. Write a short note on reflection from a rough surface.
Answer:
It causes diffused reflection, where rays scatter in all directions due to uneven surface. No clear image is formed.
41. Describe an activity to show light travels in straight line.
Answer:
Take 3 cardboards with holes and align them. Light from a candle can pass through only when they are perfectly aligned — proving light travels straight.
42. How does refraction help us see the sun before it rises?
Answer:
Atmosphere bends sunlight toward the Earth before the Sun actually rises, making it visible earlier — this is due to refraction.
43. Explain the role of iris and pupil in the eye.
Answer:
The iris controls the pupil size based on light intensity, helping regulate how much light enters the eye.
44. How can we reduce glare while driving at night?
Answer:
Use anti-glare glasses, adjust rearview mirror, and avoid looking directly into headlights.
45. What is meant by image inversion in mirrors?
Answer:
In concave mirrors (real image cases), the image is inverted (upside-down). Plane mirrors cause lateral inversion.
💡 50 "Give Reason" Questions (With Answers)
1. Give reason: A concave mirror can form both real and virtual images.
Answer: Because it can converge or diverge light depending on the position of the object.
2. Give reason: A convex mirror always forms virtual images.
Answer: Because the reflected rays diverge and never actually meet.
3. Give reason: Plane mirrors show lateral inversion.
Answer: Because the left and right sides appear reversed due to the way light reflects.
4. Give reason: A shadow is black.
Answer: Because no light reaches the area behind the object to reflect color.
5. Give reason: We cannot see in complete darkness.
Answer: Because vision is only possible when light enters the eye and forms an image on the retina.
6. Give reason: Dentists use concave mirrors.
Answer: Because they provide a magnified and clear view of teeth and inner parts of the mouth.
7. Give reason: Convex mirrors are used as rear-view mirrors.
Answer: Because they give a wide field of view and show more area behind.
8. Give reason: We see a rainbow after rain.
Answer: Due to dispersion, reflection, and refraction of sunlight by water droplets.
9. Give reason: The sun appears reddish during sunrise and sunset.
Answer: Because shorter wavelengths (blue) are scattered, and only red light reaches our eyes.
10. Give reason: Stars twinkle but planets don’t.
Answer: Because stars are point sources and their light is bent more due to atmospheric disturbances.
11. Give reason: Shadows have the same shape as the object.
Answer: Because light travels in straight lines and doesn’t bend around the object.
12. Give reason: Light reflects better from smooth surfaces.
Answer: Because smooth surfaces cause regular reflection without scattering light.
13. Give reason: A periscope uses plane mirrors.
Answer: To reflect light at 45° angles and allow the user to see over obstacles.
14. Give reason: A convex mirror gives a diminished image.
Answer: Because reflected rays appear to diverge from a smaller image.
15. Give reason: Concave mirrors are used in solar cookers.
Answer: Because they focus sunlight to a point, increasing heat.
16. Give reason: A pencil in water appears bent.
Answer: Due to refraction – light changes direction when it passes from water to air.
17. Give reason: Image in a plane mirror cannot be taken on a screen.
Answer: Because it is a virtual image, formed by rays that appear to meet but don’t.
18. Give reason: The back of a mirror is coated with silver or aluminum.
Answer: To make the surface reflective and produce a clear image.
19. Give reason: A concave mirror produces an inverted image when object is far.
Answer: Because reflected rays actually meet at a point to form a real image.
20. Give reason: A convex mirror is used in parking lots and shops.
Answer: Because it allows wide-angle viewing to monitor large areas.
21. Give reason: The image formed on the retina is real and inverted.
Answer: Because the eye lens converges light onto the retina, just like a convex lens.
22. Give reason: You see your face in a mirror but not on a wall.
Answer: Because a mirror reflects light regularly, while a wall causes diffuse reflection.
23. Give reason: Virtual images cannot be projected.
Answer: Because the light rays don’t actually meet at the image location.
24. Give reason: The Moon appears bright at night.
Answer: Because it reflects sunlight.
25. Give reason: Image formed in water appears deeper than the actual depth.
Answer: Due to refraction – light bends away from the normal when it goes from water to air.
26. Give reason: A spoon acts like a concave mirror on the inside.
Answer: Because the inner surface is curved inward and reflects like a concave mirror.
27. Give reason: A coin at the bottom of a glass of water appears raised.
Answer: Because of refraction, the light bends and makes the coin appear higher.
28. Give reason: We see the sun even before it rises.
Answer: Due to atmospheric refraction bending light toward Earth.
29. Give reason: We use multiple mirrors in kaleidoscopes.
Answer: To produce symmetrical and repeating reflection patterns.
30. Give reason: Shadows are longer in the morning and evening.
Answer: Because the Sun is at a lower angle, casting longer shadows.
31. Give reason: Optical fibers use total internal reflection.
Answer: To transmit light signals efficiently over long distances without loss.
32. Give reason: Concave mirrors can burn paper in sunlight.
Answer: Because they focus sunlight to a single point, increasing heat energy.
33. Give reason: Convex mirrors never form real images.
Answer: Because the reflected rays always diverge and do not meet.
34. Give reason: The pupil becomes smaller in bright light.
Answer: To reduce the amount of light entering the eye and protect the retina.
35. Give reason: Rods help us see in the dark.
Answer: Because they are sensitive to low light, unlike cones which need bright light.
36. Give reason: Your image in a mirror appears to be behind it.
Answer: Because the light rays reflect and appear to come from behind the mirror.
37. Give reason: We see a flickering of light over a fire.
Answer: Due to refraction caused by temperature differences in air.
38. Give reason: Concave mirrors are used by makeup artists.
Answer: Because they form enlarged, erect images when the object is close.
39. Give reason: The back surface of mirrors is painted black.
Answer: To protect the silver coating and improve image clarity.
40. Give reason: The iris controls the amount of light entering the eye.
Answer: To adjust vision in bright and dim conditions by changing pupil size.
41. Give reason: The same object can have different shadows during the day.
Answer: Because the angle and position of the sun keep changing.
42. Give reason: Plane mirrors are used in dressing rooms.
Answer: Because they produce images that are the same size and shape as the object.
43. Give reason: A convex lens focuses light to a point.
Answer: Because it bends light rays inward due to its curved shape.
44. Give reason: A beam of sunlight appears to contain dust.
Answer: Because dust particles scatter light, making them visible.
45. Give reason: You can’t see your face in a rough metal surface.
Answer: Because rough surfaces cause diffused reflection, not forming clear images.
46. Give reason: A prism splits white light into seven colors.
Answer: Due to dispersion — different wavelengths refract by different amounts.
47. Give reason: Some people wear glasses.
Answer: To correct defects in the eye lens that cause improper image formation on the retina.
48. Give reason: Total internal reflection makes diamonds sparkle.
Answer: Because light reflects multiple times inside due to their high refractive index.
49. Give reason: Eye lens becomes thin while looking at distant objects.
Answer: To reduce bending of light and focus the image on the retina.
50. Give reason: A pinhole camera forms an inverted image.
Answer: Because light travels in straight lines and crosses at the pinhole.