प्रकाश – परावर्तन तथा अपवर्तन

(Light – Reflection and Refraction)

RBSE Class 10 Science Chapter 9: Light – Reflection and Refraction (2026) — Question Bank

🌟 परीक्षा उपयोगी प्रश्न — MCQ + Very Short + Short + Long Answer

📝 Part A — Multiple Choice Questions (MCQ)

1. Light travels in:
   (a) curved path (b) straight line (c) zig-zag path (d) none
   Answer: (b)
2. The angle between incident ray and normal is called:
   (a) Angle of incidence (b) Angle of reflection (c) Angle of deviation (d) None
   Answer: (a)
3. Unit of focal length is:
   (a) metre (b) dioptre (c) cm/s (d) candela
   Answer: (a)
4. Power of a convex lens is:
   (a) positive (b) negative (c) zero (d) none
   Answer: (a)
5. The mirror used in a car headlight is:
   (a) convex (b) concave (c) plane (d) none
   Answer: (b)
6. Real image is always:
   (a) formed on screen (b) erect (c) virtual (d) none
   Answer: (a)
7. Speed of light is maximum in:
   (a) glass (b) water (c) vacuum (d) air
   Answer: (c)
8. Refractive index is the ratio of:
   (a) speed in vacuum to medium
   (b) speed in medium to vacuum
   (c) angle of incidence to refraction
   (d) none
   Answer: (a)
9. Power of lens (P) =
   (a) 1/f (b) f² (c) 2f (d) none
   Answer: (a)
10. Unit of Power of lens:
    (a) newton (b) dioptre (c) joule (d) watt
    Answer: (b)

📝 Part B — Very Short Answer Questions

1. Define reflection of light.
   Answer: The bouncing back of light from a smooth surface is called reflection.
2. State Snell’s law.
   Answer: n = sin i / sin r
3. Write mirror formula.
   Answer: 1/f = 1/v + 1/u
4. Write lens formula.
   Answer: 1/f = 1/v − 1/u
5. Define focal length.
   Answer: The distance between pole and focus is focal length.

📝 Part C — Short Answer Questions

1. What do you understand by real and virtual image?
   Answer: Real image is formed on screen and inverted. Virtual image is not formed on screen and is erect.
2. State the laws of reflection.
   Answer: 1) Angle of incidence = Angle of reflection 2) Incident ray, reflected ray and normal lie in same plane.
3. What is refractive index?
   Answer: It is ratio of speed of light in vacuum to speed in medium.

📝 Part D — Long Answer Questions

1. Explain refraction of light with ray diagram.
   Answer: When light travels from one medium to another, its speed changes causing bending. This is called refraction.
2. What is Power of Lens? Write its unit.
   Answer: Power is reciprocal of focal length in metres.
   P = 1/f
   Unit = Dioptre.

📌 Important Formulas

• 1/f = 1/v + 1/u (Mirror)
• 1/f = 1/v − 1/u (Lens)
• P = 1/f (m)
• Magnification m = v/u

🎯 Exam Tip

Sign convention याद रखें — Left negative, Right positive!

RBSE Class 10 Science – Chapter 9 Light (Reflection & Refraction) – MCQ Question Bank 2026

📌 कुल 30 बेहद महत्वपूर्ण MCQ — परीक्षा फोकस्ड

1. Light travels in —
   (a) curved path (b) straight line (c) circular path (d) none
   Answer: (b)
2. The bouncing back of light after striking a surface is called —
   (a) Reflection (b) Refraction (c) Dispersion (d) Scattering
   Answer: (a)
3. The angle between incident ray and normal is —
   (a) Angle of deviation (b) Angle of incidence (c) Angle of reflection (d) none
   Answer: (b)
4. Laws of reflection are applicable to —
   (a) plane mirror (b) concave mirror (c) convex mirror (d) all
   Answer: (d)
5. Real image is always —
   (a) erect (b) inverted (c) cannot be obtained on screen (d) none
   Answer: (b)
6. The mirror used in cars as side mirror —
   (a) Plane (b) Concave (c) Convex (d) None
   Answer: (c)
7. Unit of focal length —
   (a) dioptre (b) metre (c) watt (d) joule
   Answer: (b)
8. Power of convex lens is —
   (a) positive (b) negative (c) zero (d) none
   Answer: (a)
9. Power of lens is given by —
   (a) P = f (b) P = 1/f (c) P = f² (d) none
   Answer: (b)
10. Unit of power of a lens —
    (a) metre (b) dioptre (c) candela (d) newton
    Answer: (b)
11. Speed of light is maximum in —
    (a) air (b) glass (c) water (d) vacuum
    Answer: (d)
12. Refraction occurs due to change in —
    (a) speed of light (b) colour of light (c) source of light (d) none
    Answer: (a)
13. Mirror formula —
    (a) 1/f = 1/u + 1/v (b) 1/f = 1/v − 1/u (c) v = u (d) none
    Answer: (a)
14. Lens formula —
    (a) 1/f = 1/u + 1/v (b) 1/f = 1/v − 1/u (c) v = f (d) none
    Answer: (b)
15. Magnification (m) =
    (a) v/u (b) u/v (c) f/u (d) none
    Answer: (a)
16. Convex mirror always forms —
    (a) real & inverted image (b) virtual & erect (c) real & erect (d) none
    Answer: (b)
17. Refraction is due to —
    (a) change in wavelength (b) change in frequency (c) both (d) none
    Answer: (a)
18. Refractive index =
    (a) sin r / sin i (b) sin i / sin r (c) 1/sin i (d) none
    Answer: (b)
19. Focal length of plane mirror is —
    (a) 0 (b) ∞ (c) 1 (d) none
    Answer: (b)
20. Concave mirror forms real image when object is placed —
    (a) between F and P (b) beyond C (c) at infinity (d) all above
    Answer: (d)

Short Answer Type Questions

1. Define Reflection of Light.
   Reflection is the phenomenon of bouncing back of light from a polished surface.
2. Define Refraction of Light.
   Refraction is the bending of light when it travels from one medium to another.
3. State the two laws of reflection.
   ✔ Angle of incidence = Angle of reflection
   ✔ All rays lie in the same plane
4. Define focal length.
   Distance between pole and focus.

Long Answer Type Questions

1. Explain refraction with diagram.
   When light travels from a rarer to denser medium, it bends towards normal.
2. What is Power of Lens?
   Power = 1/f, Unit = Dioptre.

Important Numericals — Light Chapter

1. A concave mirror forms an image at 30 cm in front when object is at 60 cm. Find focal length.
   Solution: 1/f = 1/v + 1/u = 1/(-30)+1/(-60)= -1/20 → f = -20 cm
2. A convex lens has focal length 25 cm. Find its power.
   Solution: P = 1/f(m)= 1/0.25 = +4D

RBSE Class 10 Science – Chapter 9
Light: Reflection and Refraction – Worksheet (2026)

🟢 Section – A : Multiple Choice Questions

1. The bouncing back of light is called —
   (a) Reflection (b) Refraction (c) Dispersion (d) Scattering
2. Unit of focal length is —
   (a) metre (b) dioptre (c) second (d) candela
3. Real image is always —
   (a) erect (b) inverted (c) blurred (d) none
4. Speed of light is maximum in —
   (a) glass (b) water (c) vacuum (d) air
5. The mirror used as rear-view mirror in vehicles is —
   (a) plane (b) concave (c) convex (d) none
6. Power of a convex lens is —
   (a) positive (b) negative (c) zero (d) none
7. Lens formula is —
   (a) 1/f = 1/v + 1/u (b) 1/f = 1/v − 1/u (c) v = u (d) none
8. Refraction occurs due to —
   (a) change in speed (b) change in colour (c) change in source (d) none
9. Refractive index is —
   (a) sin i / sin r (b) sin r / sin i (c) 1 / sin i (d) none
10. Magnification m = —
    (a) v/u (b) u/v (c) f/v (d) u/f

🟡 Section – B : Very Short Answer (1 Mark)

1. Define reflection.
2. Define refraction.
3. Write mirror formula.
4. Write lens formula.
5. Define focal length.
6. Define power of lens.
7. Unit of power of lens?
8. Define refractive index.
9. What is real image?
10. What is virtual image?

🔵 Section – C : Short Answer (2–3 Marks)

1. State and explain laws of reflection.
2. Why does a pencil in water appear bent?
3. Differentiate between concave and convex mirror.
4. Give uses of convex mirror.
5. State sign conventions for lenses.
6. What is magnification?
7. Write two differences between real & virtual image.
8. What do you mean by optical density?
9. Define principal focus of concave mirror.
10. Why does refraction occur?

🟣 Section – D : Long Answer (4–5 Marks)

1. Explain refraction through glass slab with ray diagram.
2. Explain image formation by concave mirror in different positions with diagrams.
3. Explain rules for ray construction in convex lens with proper diagrams.
4. What is power of lens? Write its unit. Explain with examples.

🔴 Section – E : Numericals

1. A concave mirror forms an image at 30 cm in front of it when object is placed at 60 cm. Find focal length.
2. A convex lens has focal length 25 cm. Find its power.
3. An object is placed 20 cm in front of a convex lens of focal length 10 cm. Find position of image.
4. Find magnification when object distance is –15 cm and image distance is –30 cm.
5. Find power of lens whose focal length is –50 cm.

🟤 Section – F : Ray-Diagram Based Questions

1. Draw ray diagram for concave mirror when object is placed beyond C.
2. Draw ray diagram for convex lens when object is placed between F and 2F.
3. Draw ray diagram showing refraction through rectangular glass slab.
4. Draw image formation by plane mirror.

🟠 Section – G : Very Important Concept Questions

1. Why do stars appear twinkling?
2. Why is convex mirror used as rear-view mirror?
3. Why does a coin in water appear raised?
4. Why is focal length of plane mirror infinite?
5. What happens when ray passes through optical centre of lens?

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RBSE Class 10 Science — Chapter 9
Light: Reflection & Refraction (Answer Key — 2026)

🟢 Section – A : Multiple Choice Answers

1. a) Reflection
2. a) metre
3. b) inverted
4. c) vacuum
5. c) convex
6. a) positive
7. a) 1/f = 1/v + 1/u
8. a) change in speed
9. a) sin i / sin r
10. a) v/u

🟡 Section – B : Very Short Answer

1. Reflection: Bouncing back of light from a surface.
2. Refraction: Bending of light when it travels from one medium to another.
3. Mirror Formula: 1/f = 1/v + 1/u
4. Lens Formula: 1/f = 1/v − 1/u
5. Distance between pole & focus.
6. Power of lens = inverse of focal length.
7. Unit = Dioptre (D)
8. Ratio of speed of light in air to medium.
9. Image formed due to actual intersection of rays.
10. Image formed due to virtual intersection.

🔵 Section – C : Short Answers

1. Laws of Reflection:
   (i) Angle of incidence = angle of reflection
   (ii) Incident ray, reflected ray & normal lie in same plane.
2. Pencil appears bent due to change in speed of light causing refraction.
3. Concave: Converging mirror
   Convex: Diverging mirror
4. Convex mirrors give wider field view.
5. All distances from pole, sign convention applies.
6. Magnification = height of image / height of object.
7. Real image inverted, virtual erect.
8. Optical density depends on speed of light.
9. Point on principal axis where rays parallel to axis converge.
10. Due to change in optical density.

🟣 Section – D : Long Answers

1. Refraction causes deviation + emergent ray parallel to incident ray.
2. Concave mirror forms real/inverted images except when object is between pole & focus.
3. Convex lens converges & follows 3 rules:
   (i) Ray || axis → passes through F
   (ii) Ray through F → emerges || axis
   (iii) Ray through optical centre → undeviated
4. Power = 1/f (metres)
   Convex → +ve
   Concave → −ve

🔴 Section – E : Numerical Answers

1. f = −30 cm
2. P = +4D
3. v = 20 cm
4. m = +2
5. P = −2D

🟤 Section – F : Ray Diagram Answers

• Beyond C → Image between C & F (real, inverted, diminished)
• Between F & 2F → Image beyond 2F (real, inverted, enlarged)
• Glass slab → lateral displacement occurs
• Plane mirror → virtual, erect, same size

🟠 Section – G : Concept Questions

1. Due to refraction by atmosphere.
2. Gives wide field view.
3. Due to refraction causing apparent depth.
4. Plane mirror focal length = infinity.
5. Ray passes undeviated.

🎯 Marwari Mission 100™ — Teacher Answer Key 🎯

RBSE Class 10 Science — Chapter 9
Light: Reflection & Refraction (Exam Booster Crash Notes — 2026)

🌟 सबसे जरूरी पॉइंट्स जो हमेशा आते हैं

• Light travels in straight line (Rectilinear propagation)
• Reflection: Bouncing back of light
• Refraction: Bending of light when it changes medium
• Real Image: Screen पर बनती है (Inverted)
• Virtual Image: Screen पर नहीं बनती (Erect)
• Convex Lens = Converging
• Concave Lens = Diverging
• Convex Mirror = Rear View Mirror
• Concave Mirror = Headlights

📘 Laws of Reflection

• Angle of incidence = Angle of reflection
• Incident ray, reflected ray & normal — same plane

📕 Laws of Refraction (Snell’s Law)

n = sin i / sin r

Refractive Index = Speed in Vacuum / Speed in Medium

📏 Mirror Formula

1/f = 1/v + 1/u

📐 Lens Formula

1/f = 1/v − 1/u

🔍 Magnification

m = v/u

⚡ Power of Lens

P = 1/f (in metres)
Unit = Dioptre (D)

• Convex Lens → Positive Power
• Concave Lens → Negative Power

🧠 याद रखने के Short Tricks

• P = +ve ⇒ Convex Lens
• P = −ve ⇒ Concave Lens
• Virtual Image — हमेशा erect
• Real Image — हमेशा inverted (except plane mirror)
• Sign Convention: Left = Negative, Right = Positive

🎯 100% पूछे जाने वाले Concepts

• Why coin appears raised in water? → Refraction
• Why stars twinkle? → Atmospheric Refraction
• Rear-view mirror क्यों convex? → Wide field view
• Glass slab में lateral displacement होता है

📌 Numericals — Golden Rules

• Distances हमेशा metre में convert करें (Power वाले sum में)
• u हमेशा negative होता है (real object)
• Convex Lens → f = +ve
• Concave Lens → f = −ve

📝 Expected Exam Questions

• Define refraction with diagram
• Difference: Real vs Virtual Image
• Uses of convex & concave mirror
• Derive lens formula
• Numericals on power & focal length

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