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Ray Optics

Reflection of light, spherical mirrors, mirror formula, refraction of light, total
internal reflection and its applications, optical fibres, refraction at spherical surfaces, lenses,
thin lens formula, lensmaker’s formula, magnification, the power of a lens, the combination of thin
lenses in contact, refraction and dispersion of light through a prism.
Scattering of light – blue colour of the sky and reddish appearance of the sun at sunrise and sunset.
Optical instruments: Microscopes and astronomical telescopes (reflecting and refracting) and
their magnifying powers.

12th physics. NCERT notes

Reflecting Type Telescope (Cassegrian telescope)

Reflecting type Telescope (Cassegrian telescope) In such telescope, one objective lens is replaced by a concave parabolic mirror of large aperture, which is free from...
12th physics. NCERT notes

Astronomical Telescopes

Astronomical Telescopes It is used to observe distinct images of heavenly bodies. It consists of 2 lenses, the objective lens O of large focal length and...
12th physics. NCERT notes


Simple Microscope or Magnifying glass: The Magnifying power of a simple microscope is defined as the ratio of the angles subtended by the image and...
12th physics. NCERT notes

Optical Instruments: The Eye

A number of optical devices and instruments have been designed utilizing reflecting and refracting properties of mirrors, lenses and prisms. Periscope, kaleidoscope, binoculars, telescopes,...
12th physics. NCERT notes

Scattering of Light

Scattering of Light As sunlight travels through the Earth’s atmosphere, it gets scattered by a large number of molecules present in the atmosphere. According to Rayleigh where...
12th physics. NCERT notes

Refraction and Dispersion of Light through a Prism

Prism: Prism is uniform transparent medium bounded between two refracting surfaces, inclined at an angle. Refraction through a Prism: A ray of light suffers two refractions on...
12th physics. NCERT notes

Power of a Lens

Power of a lens is defined as the ability of the lens to converge a beam of light falling on the lens. If more than...
12th physics. NCERT notes

Refraction at Spherical Surfaces and Lenses

Refraction by Spherical Surfaces: A refracting surface is the part of a sphere separating two transparent media. The spherical refracting surfaces are of two types: Convex...
12th physics. NCERT notes

Total Internal Reflection

Total Internal Reflection When a ray of light enters from a denser medium to a rarer medium, it bends away from the normal. Therefore, the...
12th physics. NCERT notes

Mirror and Types of Mirror

Mirror: A smooth and highly polished reflecting surface is called a mirror. Plane Mirror A highly polished plane surface is called a plane mirror. Different properties of image...