Light Physics Cheat Sheet PDF

PRASHANT KIRAD Centre of Curvature (C): The center of the sphere of which Light the mirror's reflecting surface forms a part. - Rectilinear propagation of light - light travels in a straight line....

PRASHANT KIRAD Centre of Curvature (C): The center of the sphere of which Light the mirror's reflecting surface forms a part. - Rectilinear propagation of light - light travels in a straight line. Radius of Curvature (R): The radius of the sphere of which 8 - Speed of Light = c = 3 x 10 m/s the mirror's reflecting surface forms a part. R=2f Reflection: The bouncing back of light from any shiny surface Principal Axis: The straight line passing through the pole and e.g. mirror or water. the center of curvature of the mirror. The Laws of reflection Principal Focus (F): The point where parallel rays of light states that: either converge or appear to diverge after reflecting from the 1. The Incident ray, the mirror. Reflected ray and Focal Length (f): The distance between the pole and the Normal all lie in the principal focus. same plane. Aperture: The diameter of the reflecting surface of the 2. Angle of incidence spherical mirror. (∠i) = The angle of reflection (∠r). Ray Diagrams (i) A ray parallel to principal Plane mirror: A smooth and polished surface that reflects axis will pass through focus light uniformly. after reflection. The image formed by a plane mirror is : always virtual and erect. (iii) A ray passing through size of the image is equal to that of the object. center of curvature will image formed is as far behind the mirror as the object is follow the same path back in front of it. after reflection. image is laterally inverted. Spherical mirror: a mirror whose reflecting surface is part (ii) A ray passing through of a hollow sphere of glass. the principal focus will CONCAVE MIRROR become parallel to reflecting surface is curved inwards, principal axis after towards the center of the sphere reflection CONVEX MIRROR reflecting surface is curved outwards. (iv) Ray incident at pole is Pole (P): The center point of the reflected back making same reflecting surface of a spherical angle with principal axis. mirror. CONCAVE MIRROR CONVEX MIRROR Sign Conventions for Spherical Mirrors: The object is always placed to the left of the mirror. Distances are measured from the pole of the mirror. Distances along the incident ray (+X-axis) are positive, and those against it (-X-axis) are negative. Distances above the principal axis are positive. Object distance = always +ve Distances below the principal axis Focal length of concave mirror = -ve are negative. Focal length of convex mirror = +ve Important Formulas: h’ = positive (virtual images) h’ = negative (real images) m = negative (real) m = positive (virtual) Magnification refers to the ratio of the height of an image to the height of an object Refraction of Light Phenomenon of change in the direction of light when it passes from one transparent medium to another. Laws of refraction of light. (i) The incident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence, all lie in Uses of Concave Mirrors: the same plane. Torches, Search-lights, and Vehicle Headlights: Shaving Mirrors Dentist's Mirrors Snell’s law of refraction. Solar Furnaces Uses of Convex Mirrors: Rear-view Mirrors in Vehicles: Refractive index: Preferred in Vehicles: Provide erect, though diminished, images. Have a wider field of view due to their outward curve. measurement of how much a light ray bends when it passes Allow drivers to view a larger area compared to plane mirrors. from one medium to another.  Lenses: A transparent material bound by two surfaces, of which one or both surfaces are spherical. CONVEX LENS CONCAVE LENS CONCAVE LENS Convex Lens – Thicker in the middle, converges light. Concave Lens – Thicker at edges, diverges light. Centre of Curvature (C₁, C₂) – Center of the sphere forming the lens surface. Principal Axis – Straight line through both curvature centers. Optical Centre (O) – Central point where light passes undeviated. Aperture – Effective diameter of the lens. Principal Focus (F₁, F₂) – Point where parallel rays converge (convex) or diverge (concave). Focal Length (f) – Distance between the principal focus and optical center. (i) A ray of light from the object, parallel to the principal axis (ii) A ray of light passing through a principal focus Uses of Convex Lens: (iii) A ray of light passing through the optical Uses of Concave Lens: centre of a lens overhead projector spy holes in the doors camera glasses focus sunlight some telescopes simple telescope CONVEX LENS projector microscope magnifying glasses Lens formula: Power of Lens: The ability of a lens to converge or diverge the ray of light after refraction through it is called the power of the lens. It is defined as the reciprocal of focal length. ‘ SI unit = Dioptre (D) 1 dioptre is the power of a lens whose focal length is 1 metre. 1D = 1m. power of a convex lens = positive power of concave lens = negative. Chapter ka KAZAANA: Numerical Mirror Formula Lens Formula Power of Lens All Ray Diagrams Snell’s Law