# Ray Optics Class 12 Notes – Physics Chapter 9 Notes

## Ray Optics Class 12 Notes

Reflection of Light: Light is viewed as a beam that moves in a linear fashion in this optics. It claims that there is a vision for every item. The process of changing the direction of light without modifying the medium is known as reflection. Reflection of light occurs when the light returns to the same medium from which it came after hitting a material.

Laws of Reflection: The following are two reflection laws:
(i) The incidence angle i is equal to the reflection angle r, i.e. ∠i = ∠r. (ii) At the point of incidence, the incident ray, reflected ray, and normal to the reflector are all in the same planes.

Sign Convention: All dimensions must be collected from the mirror’s pole. All observations taken in the direction of the propagation beam will be positive, while those taken in the reverse direction will be negative. All lengths above and below the principal shaft are measured as positive, and all distances underneath the principal axis are measured as negative.

Mirror Equation: The mirror equation is a relationship between the mirror’s focal length and the distances between entities and their images. The relationship between object distance (u), image distance (v), and focal length (f).

Spherical Mirror Focal Length: (a) The focal length of the mirror is the width between the focus and the pole, and it is denoted by f.
(b) A concave mirror has a negative focal length, while a convex mirror has a positive focal length.
(c) A mirror’s focal length is equivalent to 1/2 of the mirror’s radius of curvature.

Linear Magnification: The linear magnification generated by a spherical mirror is calculated as the proportion of the image size projected by the spherical mirror i to the object size O.

Refraction: The refraction of light is the occurrence of a shift in the course of rays of light as it travels diagonally from one transparent material to the other.

Laws of Refraction: (i) The incident, normal, and refracted rays all lie in the very same planes. (ii) The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for the same set of medium and the same hue of light, i.e.

The following should be obvious if n21 is the refractive index of medium 2 with respect to medium 1 and n12 is the refractive index of medium 1 with respect to medium 2.

Refractive Index: It’s the proportion of the speed of light in a vacuum to the speed of light in the media.

Critical Angle: In a denser media, the critical angle is the angle of incidence where the refracted ray just skims the partition barrier.

Total Internal Reflection: Total internal reflection is the occurrence in which a beam of light moving from a denser to a rarer media at an angle of incidence larger than the critical angle is completely reflected back into the optically dense medium.

The refraction and internal reflection of beams from spot A in a denser medium (water) incident at various angles at the contact with a rarer medium are depicted in this figure (air).

Apparent Depth of Liquid: When an artefact is placed at the bottom of a transparent material, such as water, and seen from above, it appears to be higher than it really is.

Lens Maker Formula: Surfaces with appropriate radii of curvature can be used to build lenses with specified focal lengths.

Magnification: The proportion of the size of the image to the object size is characterised as magnification (m) generated by a lens, just as it is for that mirror. It is readily shown that a lens, continues in the very same manner as a spherical mirror.

Power: The capability of a lens P to deflect the beam towards the axis is known as its power.

Combination of two contact lenses: This formula works for any number of thin contact lenses. When many lenses with focal lengths of f0, f1, f2, etc. are in touch, the effective focal length of their aggregate is determined by the formula below.

The angle of Deviation: The angle of minimal deviation, denoted by delta, is the smallest value of the angle of deviation caused by a ray when travelling through a prism.

Dispersion: The dispersion of light is the dividing of white light into its constituent colours. A prism creates both dispersion and deviation. The spectrum is the arrangement of coloured bands that are displayed.

Angular dispersion: The angular separation between the contrasting colours in the spectra (violet and red) is known as angular dispersion.

Optical Instruments: Optical instruments are equipment that aids the human eye in viewing high magnification images of small things, performing extensive examinations, and watching very distant objects, whether earthly or celestial.

Accommodation of Human Eye: Human eye accommodation is the capability of the eye lens to adjust its focal length, allowing pictures of objects at different distances to be generated on the same retina.

Human Eye: (a) This is the most well-known and complex optical instrument given to living creatures by creation. Light comes through a curving front surface called the cornea and travels through the pupil – the primary hole in the iris – in this apparatus. (b) The light is focussed on the retina via the eye lens. (c) The retina detects light intensity and colour and sends electrical brain signals via optical nerves. (d) The information is finally processed by the brain.

## Summary – Ray Optics Class 12 Notes

All of the major equations and principles from the course are covered in the Ray Optics Class 12 Notes. Even if you just want a fast summary of a chapter, concise revision notes can help you out. These lessons will undoubtedly save you energy on exam days when you are under pressure.

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