🔦 Chapter 10 – Light: Mirrors and Lenses
🌟 Introduction
- 🪞 Plane mirrors → form erect & same-size images
- 🔄 Curved mirrors → form different images:
- Enlarged
- Diminished
- Inverted
- Erect
👉 These curved mirrors are called:
Spherical Mirrors
🪞 10.1 What Are Spherical Mirrors?
📌 Definition:
Mirrors whose reflecting surface is part of a sphere
🔄 Types of Spherical Mirrors
🔹 1. Concave Mirror
- Reflecting surface curves inward
🔸 2. Convex Mirror
- Reflecting surface curves outward
🥄 Example:
- A shiny spoon acts like a spherical mirror
👉 Inner side → concave
👉 Outer side → convex
⚙️ How Mirrors Are Made
- Glass is curved and polished
- Coating decides type:
Coating Position | Mirror Type |
Outer surface | Concave |
Inner surface | Convex |
🔍 10.2 Image Formation by Mirrors
🪞 1. Concave Mirror
📌 Characteristics:
- Object near → image erect & enlarged
- Object far → image inverted
🔄 Image Nature:
- Can be:
- Erect
- Inverted
- Enlarged
- Diminished
👉 Depends on object distance
🚗 2. Convex Mirror
📌 Characteristics:
- Image is always:
- Erect
- Diminished (smaller)
🔄 Distance Effect:
- Image becomes slightly smaller as object moves away
🪞 3. Plane Mirror
📌 Characteristics:
- Image is:
- Erect
- Same size
🔁 Special Property:
- Lateral inversion (left-right reversal)
🛠️ Uses of Mirrors
🔦 Concave Mirrors
- Torch reflectors 🔦
- Car headlights 🚗
- Dentist mirror 🦷
- Telescopes 🔭
🚘 Convex Mirrors
- Side-view mirrors
- Road safety mirrors
- Security mirrors in shops
👉 Provide wide field of view
📐 10.3 Laws of Reflection
📌 Important Terms:
- Incident Ray → incoming light
- Reflected Ray → outgoing light
- Normal → perpendicular line
📏 Angles:
- Angle of incidence (i)
- Angle of reflection (r)
⭐ Laws of Reflection:
1.
Angle of incidence = Angle of reflection
2.
Incident ray, reflected ray, and normal lie in same plane
🔄 Reflection in Different Mirrors
- Plane mirror → parallel rays remain parallel
- Concave mirror → rays converge
- Convex mirror → rays diverge
🔥 10.3.1 Concentration of Light
🔆 Concave Mirror:
- Can focus sunlight to a point
👉 Heat increases → can burn paper
⚙️ Applications:
- Solar cookers 🍳
- Solar furnaces
- Power generation
🔍 10.4 What Is a Lens?
📌 Definition:
Lens = Transparent object that allows light to pass through
🔄 Types of Lenses
🔹 1. Convex Lens
- Thicker in middle
- Converges light
🔸 2. Concave Lens
- Thinner in middle
- Diverges light
⚠️ Difference from Mirror:
- Mirrors → reflect light
- Lenses → allow light to pass
🔎 10.5 Image Formation by Lenses
🔍 1. Convex Lens
📌 Characteristics:
- Object near → erect & enlarged
- Object far → inverted
🔄 Image can be:
- Enlarged
- Diminished
- Erect
- Inverted
🔍 2. Concave Lens
📌 Characteristics:
- Image always:
- Erect
- Diminished
🔄 10.6 Convergence and Divergence
🔹 Convex Lens:
Converging Lens
🔸 Concave Lens:
Diverging Lens
🔥 Important:
- Convex lens can also burn paper by focusing sunlight
🎯 10.7 Uses of Lenses
👓 Daily Life:
- Eyeglasses
🔬 Instruments:
- Microscopes
- Telescopes
- Cameras 📸
👁️ Human Eye:
- Contains convex lens
- Changes shape to focus
📌 Snapshots (Quick Revision)
⚡ One-Line Points
- Concave mirror:
- Forms all types of images
- Convex mirror:
- Always erect & diminished
- Laws of reflection:
- i = r
- Rays lie in same plane
- Concave mirror → converges light
- Convex mirror → diverges light
- Convex lens:
- Converges light
- Forms different types of images
- Concave lens:
- Always erect & diminished
- Diverges light
🎯 Final Conclusion
Light behaves differently depending on:
🔑 Mirror shape + Lens type
🌟 Final Formula:
Reflection + Refraction = Image Formation
🧠 Learning Outcome:
- Understand mirrors & lenses
- Identify image types
- Apply concepts in real life
