Class 10 Science Chapter 9 Revision Notes – Light: Reflection and Refraction

Class 10 Science Chapter 9 – Revision Notes: Light: Reflection and Refraction

• Focal length & radius of curvature: f = R/2 for spherical mirrors.
• Mirror formula: 1/v + 1/u = 1/f (sign convention: distances measured from the pole, distances against incident light direction are negative).
• Magnification (mirror): m = -v/u = h’/h.
• Lens formula: 1/v – 1/u = 1/f.
• Magnification (lens): m = v/u = h’/h.
• Power of a lens: P = 1/f (f in metres); SI unit dioptre (D). Convex lens: positive power. Concave lens: negative power.
• Lens combination in contact: P_combined = P1 + P2 + …
• Refractive index: n = speed of light in vacuum / speed of light in medium = c/v.
• Concave mirror images: real & inverted when object is beyond F; virtual, erect & magnified when object is between pole and F.
• Convex mirror images: always virtual, erect, and diminished, regardless of object position.
• Convex lens images: real & inverted when object is beyond F; virtual, erect & magnified when object is between the lens and F.
• Concave lens images: always virtual, erect, and diminished.

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Written by Satish

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