NCERT Solutions For Class 12 Physics Chapter 9: Ray Optics and Optical Instruments

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NCERT Solutions for Class 12 Physics Chapter 9 Ray Optics and Optical Instruments are provided in this article. Optics helps us study the properties and behaviour of light. In Ray Optics, the light travels in a straight line stating that there is an image for each and every object. The optical devices made utilising reflecting and refracting properties of lenses, mirrors and prisms known as Optical instruments.

Class 12 Physics Chapter 9 is a part of Unit 6 Optics which along with Unit 5 Electromagnetic Waves has a weightage of 18 marks in the CBSE Class 12 Board exam. The NCERT Solutions for Class 12 Physics Chapter 9 covers concepts of refraction, Snell’s Law, and total internal reflection

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NCERT Solutions for Class 12 Physics Chapter 9

NCERT Solutions

Class 12 Physics Chapter 9 – Important Topics Covered

Ray Optics is the branch of physics that deals with the behaviour of light as a ray which travels in a straight line.

Light always travels in a straight line. It does not require any medium to travel

Reflection is the phenomenon wherein light changes its path without any change in the medium.

Laws of Reflection

The angle of incidence, represented as i is equal to the angle of reflection, represented as r.
∠i = ∠r.
The incident ray, the reflected ray and the normal to the reflecting surface at the incidence point, all lie in the same plane.

The mirror formula represents a relation between the focal length of the mirror and the distances of objects and images from the mirror.

${1 \over v} + {1 \over u} = {1 \over f} $

Linear Magnification: The ratio of the size of the image that is formed by a spherical mirror I to the size of the object O is known as linear magnification.

$m={I \over O}={-v \over u}$

Refraction is the phenomenon of change in the path of light as it goes from one medium to another.

Laws of Refraction

The incident ray, refracted ray and the normal to the refracting surface at the point of incidence, all lie in the same plane.
The ratio of the sin of the angle of incidence to the sin of the angle of refraction is constant for any two given mediums. This constant is the relative refractive index.

n = sin i/sin r (Snell’s law)

where, n is the refractive index of the second medium when first medium is air.

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CBSE CLASS XII Related Questions

1.
The resistance of a metal wire at $ 20^\circ \text{C} $ is $ 1.05 \, \Omega $ and at $ 100^\circ \text{C} $ is $ 1.38 \, \Omega $. Determine the temperature coefficient of resistivity of this metal.

View Solution

2.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

View Solution

3.
An electric field $\vec{E}$ is established across the ends of a cylindrical conductor of length L and area of cross-section A. Discuss how electrons attain an average velocity, independent of time. Hence, obtain a relation between current in the conductor and this ‘average velocity’ of electrons.

View Solution

4.
Read the following paragraph and answer the questions that follow.
A p-type or n-type semiconductor can be converted into a p-n junction by doping it with suitable impurity. The motion of majority charge carriers causes diffusion current across the junction while the barrier electric field causes motion of minority carriers for drift current. In case of unbiased diode, the diffusion and drift currents are equal. This equilibrium is disturbed by the biasing batteries. Diodes, therefore, allow currents in one direction. This property of diode is used in making rectifiers.

5.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

View Solution

6.
An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.

NCERT Solutions For Class 12 Physics Chapter 9: Ray Optics and Optical Instruments

NCERT Solutions for Class 12 Physics Chapter 9

Class 12 Physics Chapter 9 – Important Topics Covered

CBSE CLASS XII Related Questions

1.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

2.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

5.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

Similar Physics Concepts

Comments

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NCERT Solutions For Class 12 Physics Chapter 9: Ray Optics and Optical Instruments

NCERT Solutions for Class 12 Physics Chapter 9

Class 12 Physics Chapter 9 – Important Topics Covered

CBSE CLASS XII Related Questions

1. The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

2.With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

5.This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

2.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

5.
This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?