Reflection of Light — Maharashtra (SSC) Class 9 Science Solutions (Free)

Law 1: The angle of incidence equals the angle of reflection (both measured from the normal). Law 2: The incident ray, reflected ray, and normal all lie in the same plane. Example: When light hits a mirror at 30° from normal, it reflects at 30° on the other side. These laws apply to all reflective surfaces and enable accurate prediction of light paths.

Regular reflection occurs on smooth, polished surfaces like mirrors and still water, where parallel rays reflect parallel, forming clear images. Diffuse reflection occurs on rough surfaces like paper and walls, where rays scatter in different directions due to surface irregularities, preventing clear image formation. Regular reflection is used in mirrors and telescopes; diffuse reflection allows us to see non-luminous objects from all angles.

A concave mirror has an inward-curved reflecting surface that converges light rays. Image types depend on object position: (1) Beyond center - real, inverted, diminished, (2) At center - real, inverted, same size, (3) Between center and focus - real, inverted, magnified, (4) At focus - no image forms, (5) Between focus and mirror - virtual, erect, magnified. Concave mirrors focus light for applications like solar furnaces and flashlights.

A convex mirror has an outward-curved surface that diverges light rays. Images formed are: virtual (behind mirror), erect, diminished, and formed between pole and focus regardless of object position. Practical applications: (1) Vehicle side mirrors for wide field of view, (2) Security mirrors in shops and corners, (3) Safety reflectors on roads. Convex mirrors reduce blind spots and provide safety advantages.

Focal length (f) is the distance from the mirror's pole to the focal point where parallel rays converge (concave) or diverge from (convex). Radius of curvature (R) is the distance from the pole to the center of the circular surface. They relate by: f = R/2. For a concave mirror, f is positive; for a convex mirror, f is negative. This relationship helps calculate image positions using the mirror equation.

Mirror equation: 1/f = 1/u + 1/v, where u is object distance and v is image distance. Given: h = 5 cm, u = 30 cm, f = 10 cm. Calculation: 1/10 = 1/30 + 1/v, so 1/v = 1/10 - 1/30 = 2/30, v = 15 cm. Magnification m = -v/u = -15/30 = -0.5. Image is 15 cm from mirror, real, inverted, and half the object size.