๐ Class 7 Science Curiosity – Chapter 11 Notes
๐ฆ Light: Shadows and Reflections | Amresh Academy
๐ Introduction
๐ก 1. Sources of Light
๐ Luminous Objects:
๐ Produce their own light
- ☀️ Sun
- ⭐ Stars
- ๐ Fireflies
- ๐ก Bulbs
๐ Non-Luminous Objects:
- ๐ Moon
๐ฟ Types of Sources:
- ๐ Natural → Sun, stars, lightning
- ๐ฏ️ Artificial → Candle, bulb, LED
⚡ LED Lamps:
- Energy efficient ๐ก
- Long-lasting
- Eco-friendly ๐
๐ 2. Light Travels in a Straight Line
๐งช Experiments:
- ๐ฆ Matchbox → Light passes through aligned holes
- ๐ง Pipe → Straight pipe shows flame, bent pipe doesn’t
- ๐ด Laser → Moves straight even in water
๐งฑ 3. Light and Materials
๐ Types:
✔️ Transparent:
๐ Light passes completely
- Glass
๐ซ️ Translucent:
๐ Light passes partially
- Tracing paper
❌ Opaque:
๐ Light is blocked
- Cardboard
๐ 4. Shadow Formation
๐ Shadow:
๐ Dark region formed when light is blocked
๐ Requirements:
- Light source ๐ก
- Opaque object ๐งฑ
- Screen (wall)
๐ง Observations:
- Opaque → dark shadow
- Translucent → light shadow
- Size depends on position
- Color doesn’t affect shadow
๐ช 5. Reflection of Light
๐ Definition:
๐ Light bounces back from a surface
๐ Example:
- Mirror ๐ช
- Shiny surfaces
๐ช 6. Images in a Plane Mirror
๐ Properties:
- Same size ๐
- Upright (erect) ✔️
- Virtual image
- Laterally inverted ๐ (left-right reversed)
๐ Example:
๐ “AMBULANCE” appears reversed in mirror
๐ท 7. Pinhole Camera
๐ Definition:
๐ Device that forms image through a small hole
๐ง Image Properties:
- Inverted (upside down) ๐
- Shows colors ๐จ
๐ ️ Construction:
- Cardboard box
- Small hole
- Screen
๐ 8. Useful Devices
๐ญ Periscope:
- Uses mirrors
- Helps see around corners
๐จ Kaleidoscope:
- Uses mirrors
- Creates beautiful patterns
๐ Final Summary
๐ Light helps us understand:
- Shadows ๐
- Reflection ๐ช
- Images ๐ท
๐ Key Concepts:
- Light travels straight ๐
- Materials affect light ๐งฑ
- Mirrors form images ๐ช
- Devices use reflection ๐ญ
✨ Perfect for revision + exams + concept clarity ๐
