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

 

NCERT solutions for class 12 Physics chapter 9 Ray Optics and Optical Instruments: Do you know what is a mirage? Have you ever experienced it? The NCERT solutions for class 12 Physics chapter 9 Ray Optics talks about a few natural phenomena due to light such as mirage, also describes laws of refraction and reflection and introduces a few optical instruments. NCERT grade 12 chapter 9 has a higher weight for CBSE board examination. Here our subject matter experts provide NCERT solutions for class 12 Physics chapter 9 Ray Optics and Optical Instruments in detail. This chapter has a high weight as far as competitive exams are considered.

NCERT solutions for class 12 Physics chapter 9 Ray Optics and Optical Instruments: important formulas. The important formulas of NCERT class 12 chapter 9 are listed below. Try to understand those formulas and study their derivation if available in NCERT book.

Formula

Description

Mirror equation:

v is object distance from the pole of the mirror.

u is the image distance from the pole of the mirror.

F is the focal length of the mirror which is approximately equal to half the radius of curvature

Magnification of a mirror

m= \frac{h_{i}}{h_{o}}= \frac{-v}{u}

h_{i}= height of the image from the principal axis

h_{o}= height of the object from the principal axis

If a prism of refractive index n2is placed in a medium of refractive index n1then

\boldsymbol{\frac{n_2}{n_1} = \frac{\sin \left ( \frac{D _{m}+A}{2} \right )}{\sin \left ( A/2 \right )}}

A is the angle of the prism

Dm is the angle of  minimum deviation

 

Thin lens formula

\frac{1}{v}-\frac{1}{u}= \frac{1}{f}

 

Lens makers formula

\boldsymbol{\frac{1}{f}= \left ( \frac{\mu _{2}}{\mu _{1}}-1 \right )\left ( \frac{1}{R_{1}}- \frac{1}{R_{2}}\right )}

v, u are image and object distance from the optical centre of the lens and f is the focal length.




 

\mu _{1}= refractive index of the medium of the object

\mu _{2}= refractive index of the lens

R_{1}\, and \, R_{2} are the radius of curvature of two surface

Power of a lens

\boldsymbol{P=\frac{1}{f}}

Where P is the power and f is the focal length in meters

The magnifying power of a simple microscope m=1+ \frac{D}{f}

For compound microscope magnification m=mem0

D = 25 cm is the least distance of distinct vision and f is the focal length of the convex lens

me is magnification due to the eyepiece.

mo is magnification produced by objective.

For a telescope magnifying power is given by

m=\frac{\beta}{\alpha}=\frac{f_o}{f_e}

Beta is the angle subtended by eyepiece at the image

Alpha is the angle subtended at the eye bu the object

One important concept in NCERT  class 12  chapter 9 Ray Optics is the total internal reflection.

NCERT solutions for class 12 Physics chapter 9 Ray Optics and Optical Instruments: Main topics and subtopics

9.1 Introduction

9.2 Reflection of Light by Spherical Mirrors

9.2.1 Sign convention

9.2.2 Focal length of spherical mirrors

9.2.3 The mirror equation

9.3 Refraction

9.4 Total Internal Reflection

9.4.1 Total internal reflection in nature and its technological applications

9.5 Refraction at Spherical Surfaces and by Lenses

9.5.1 Refraction at a spherical surface

9.5.2 Refraction by a lens

9.5.3 Power of a lens

9.5.4 Combination of thin lenses in contact

9.6 Refraction through a prism

9.7 Some Natural Phenomena Due to Sunlight 

9.7.1 The rainbow

9.7.2 Scattering of light

9.8 Optical Instruments

9.8.1 The microscope

9.8.2 Telescope

Each and every topic of chapter 9 Ray Optics and Optical Instruments are important for exams and there is no scope of skipping any topic.

NCERT solutions for class 12 Physics chapter 9 Ray Optics and Optical Instruments are explained below:

Q- 9.1 A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? Describe the nature and size of the image.

Q-9.2A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror.

View all solved questions here.

NCERT Solutions for Class 12 Physics- Chapter wise

Chapter 1

Electric Charges and Fields

Chapter 2

Electrostatic Potential and Capacitance

Chapter 3

Current Electricity

Chapter 4

Moving charges and magnetism

Chapter 5

Magnetism and Matter

Chapter 6

Electromagnetic Induction

Chapter 7

Alternating Current

Chapter 8

Electromagnetic Waves

Chapter 10

Wave Optics

Chapter 11

Dual nature of radiation and matter

Chapter 12

Atoms

Chapter 13

Nuclei

Chapter 14

Semiconductor Electronics: Materials, Devices and Simple Circuits

NCERT Solutions for Class 12

 

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