ICSE Class 9 | Chapter 7 Reflection of Light | Ex 7 a 7b 7c | Solved Numericals | Concise Physics

ICSE Class 9 | Chapter 7 Reflection of Light | Ex 7 a 7b 7c | Solved Numericals | Concise Physics ================================ Reflection of light is the phenomenon where light rays bounce back into the same medium after striking a surface. This process allows us to see most objects around us that do not produce their own light. Key Theoretical Concepts 1. Laws of Reflection These two laws apply to all reflecting surfaces, including plane and spherical mirrors. First Law: The incident ray, the reflected ray, and the normal at the point of incidence all lie in the same plane. Second Law: The angle of incidence equals the angle of reflection (∠i = ∠r), measured from the normal. 2. Types of Reflection Reflection depends on the surface's smoothness. Regular (Specular) Reflection: Occurs on smooth surfaces like mirrors, where parallel rays reflect as parallel rays, creating clear images. Irregular (Diffuse) Reflection: Occurs on rough surfaces, where parallel rays scatter in various directions, making objects visible but without a clear image. 3. Key Terminology Terms associated with reflection include the incident ray (striking the surface), point of incidence, reflected ray (bouncing back), normal (perpendicular to the surface), angle of incidence (between incident ray and normal), and angle of reflection (between reflected ray and normal). 4. Image Formation An image forms where reflected rays meet or appear to meet. Real Image: Formed by actual intersection of reflected rays, always inverted, and can be projected on a screen. Virtual Image: Formed when reflected rays appear to diverge from behind the mirror, always upright, and cannot be obtained on a screen. 5. Characteristics of an Image in a Plane Mirror The image is virtual, erect, the same size as the object, located as far behind the mirror as the object is in front, and exhibits lateral inversion (left-right reversal). 6. Multiple Reflection Placing an object between two inclined mirrors can produce multiple images due to successive reflections. The number of images depends on the angle between the mirrors; parallel mirrors (0° angle) create infinite images.