Light — Reflection and Refraction — Complete Lesson
?? Reflection of Light
Laws of Reflection:
- The angle of incidence = angle of reflection (?i = ?r)
- The incident ray, reflected ray, and normal all lie in the same plane
?? Spherical Mirrors
| Feature | Concave Mirror | Convex Mirror |
|---|---|---|
| Shape | Caves inward (like a spoon) | Bulges outward |
| Image | Real or virtual (depends on position) | Always virtual, erect, diminished |
| Use | Torches, headlights, dentist mirror | Rear-view mirrors, ATM cameras |
?? Refraction of Light
When light passes from one medium to another, it bends. This bending is called refraction.
Mirror Formula: 1/v + 1/u = 1/f
Lens Formula: 1/v - 1/u = 1/f
Magnification: m = v/u = h'/h
Light — MCQ Practice
Light — Reflection and Refraction — Mnemonic
Mnemonic 1: For Laws of Reflection 📏✨
"Incident Angle = Reflected Angle, Normal is the Middle Man"
Explanation: The angle of incidence equals the angle of reflection, and both angles are measured with respect to the normal (the "middle man" line perpendicular to the surface).
Mnemonic 2: Refraction Through Different Media 🌈👓
"Air to Glass? Speed will Pass!"
Meaning: When light passes from air to glass, it slows down and bends towards the normal.
Mnemonic 3: Hindi Rhyming Trick for Refraction Sequence 🇮🇳📚
"Hawa se Pani, Roshni Jhat se Mani" 🌬️💧
Translation: Light bends quickly when going from air (hawa) to water (pani).
Use: Helps remember that light bends towards the normal when entering a denser medium like water.
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