Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Thin Lens Formula: It is a relation between focal length of a lens and distance of object and image from optical centre of the lens. Let O be the optical centre and f be the principal focus of a convex lens of focal length OF= f, Distance of […]
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Image Formation in Lenses Using Ray Diagrams: (I) Rays which are parallel to the principal Axis after refraction, will passes through principal focus in case of convex lens and will appear to be coming from principal focus in case of concave lens. (II) Rays passing through or directed
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Lens: Lens is a transparent refracting medium bounded by two surfaces, one of which must be spherical. Lenses are two types- (I) Convex or converging lens (II) Concave or diverging lens Convex Lens: A lens which is thicker at the centre and thinner at its ends is called
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Refraction at a Spherical Surface: We will consider two transparent medium of refractive index n₁ and n₂, the boundary between two surfaces is a spherical surface of radius R. Assumptions: 1. All the rays are paraxial, that means P and P’ are coincide. 2. θ₁ and θ₂ are very
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Total Internal Reflection(TIR): When a Ray of light strikes the interface at the angle greater than Critical Angle, it comes back in the same medium, this phenomenon is called total internal reflection(TIR). Necessary Conditions for TIR: 1. The light must travel from denser to rarer medium. 2. Angle
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Law of Refraction: First Law:- The incident ray, the refracted ray and the normal to the refracting surface at the point of incidence, all lie in the same plane. Second Law(Snell’s Law):- The ratio of the sine angle of incidence to the Sine angle of refraction is constant
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Refraction: The bending of light when it passes from one medium to another of different optical density is called refraction. When a beam of light encounters another transparent medium, a part of light gets reflected back into the first medium, while the rest enters the other. The direction
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Linear Magnification: The ratio of the height of the image(h´) formed by a spherical mirror to the height of the object(h) is called the linear magnification produced by the spherical mirror. It is denoted by m. m= h´/h
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Mirror Formula: We consider and object AB placed on the principal axis beyond the centre of curvature C of a concave mirror of small aperture. A ray AM from the object travels parallel to the principal axis and after reflection from the mirror it passes through focus F.
Chapter-9|Ray Optics and Optical Instrument|NCERT 12th Physics: Focal Length of Spherical Mirrors: We consider a ray AB parallel to principal axis, incident at point B of a spherical mirror(concave or convex) of small aperture. After reflection from the mirror, this ray converges to point F(in case of concave mirror) or appears to diverge from point
