NCERT Class 12 Physics Chapter 10 Notes Wave Optics - Download PDF

# NCERT Class 12 Physics Chapter 10 Notes Wave Optics - Download PDF

Edited By Vishal kumar | Updated on Mar 19, 2024 11:42 AM IST

The NCERT chapter on optics is followed by the chapter Wave optics. The Class 12 Physics chapter 10 notes provide a high-level overview of the chapter's wave optics. Wavefront and Huygens principle are the key concepts addressed in notes for Class 12 Physics chapter 10. The chapter's basic equations are also addressed in Class 12 Physics chapter 10 notes. In the CBSE Class 12 Physics chapter 10 notes, the relevant derivations are not discussed.

The wave theory of light was first proposed in 1678 by a Dutch physicist. The causes of reflection and refraction were explained using this paradigm. When the speed of light is slower than the speed of the second medium in refraction, the light wave bends towards regularity. Certain fundamentals will be learned by students who read the Class 12 wave optics notes. The understanding of light and its wave optics will aid in the overall development of young students. Students can also get the Class 12 Physics Chapter 10 notes in pdf format.

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## NCERT Class 12 Physics Chapter 10 Notes

• WaveFront:

A light source is a spot that radiates noise in all directions. In a homogeneous medium, the disturbance hits all of the medium's particles in phase, which is all placed at the same distance from the light source, and so every particle must vibrate in phase with each other at all times. The wavefront is the location of all medium particles that are vibrating in the same phase at any given time.

Wavefronts can be one of the following sorts, depending on the shape of the light source:

1. Spherical wavefront

2. Cylindrical wavefront

Spherical WaveFront: A spherical wavefront is created by a point source of light. This is due to the fact that the locus of all equidistant points from the point source is a sphere.

Cylindrical WaveFront: A cylindrical wavefront is produced when the light source is linear (such as a slit). Every equidistant point from the linear source is located on the surface of a cylindrical

Plane WaveFront: If a wavefront is a small component of a spherical or cylindrical wavefront originating from a distant source, it will appear plane. As a result, it's known as a plane wavefront

### Huygens' Principle

Huygens' principle is a geometrical construction that can be used to calculate the new position of a wavefront at a later time from its current position. Or, to put it another way, this principle provides a means for determining how light spreads out in a material.

It is founded on the following assumptions:

1. All of the locations on a given or primary wavefront operate as a source of secondary wavelets, which, like the primary light source, sends out disruption in all directions.

2. The envelope of the secondary wavelets at any instant is the new position of the wavefront (called secondary wavefront).

• The Superposition Principle:

When two or more waves superimpose at a single medium particle, the resultant displacement (y) of the particle is equal to the vector sum of the displacements (y1 and y2) produced by separate waves i.e, y=y1 + y2

• Phase/Phase difference/Path difference/Time difference
Phase is defined as the sine or cosine argument in the calculation for wave displacement.

For displacement

Phase difference (ϕ): The difference between the phases of two waves at a given place is known as phase difference.

i.e.,

and

so phase difference = ϕ

Path difference (Δ): The difference in path lengths of two waves meeting at a place is referred to as path difference.

T.D. (Time Difference): T.D. (Time Difference) is the time difference between two waves meeting at a place. =

If we have two waves y1=a1sinωt and where y2=a2sin(ωt+ϕ),a1 and a2 =Individual amplitudes, ϕ= phase difference I1and I2= Intensities of Individual waves.

## Resultant Amplitude

We know

K is constant

Resultant intensity =

• Coherent sources:

Coherent sources of light are light sources that emit continuous light waves of the same wavelength, frequency, and phase (or with a constant phase difference).

• Interference of light:

Interference of light occurs when the intensity of light is highest at certain spots and lowest at others due to the simultaneous superposition of two waves of exactly the same frequency (originating from two coherent sources) travelling in the same medium and in the same direction.

• Types of Interference:

 Constructive interference Destructive interference Constructive interference occurs when two waves of the same phase collide at the same location (i.e., maximum light) When the waves collide at a place with the opposite phase, destructive interference occurs (i.e., minimum light) Phase difference Path difference Path difference

## Young’s Double Slit Experiment (YDSE)

When monochromatic light (single wavelength) falls on two narrow slits S1 and S2 that are very close together, they act as two coherent sources, and the waves from these two sources superimpose on each other, an interference pattern appears on the screen. In this experiment, bright and dark bands alternated on the screen. Fringes are the name given to these bands.

d is the distance between the slits.

D be the distance between the slits and the screen.

= Monochromatic light emanating from the source's wavelength.

1. At the central position Φ=0o or Δ=0 the Central fringe will always be bright

2. A slit's fringe pattern will be brighter than a point's fringe pattern.

3. If the slit widths are mismatched, the minima will not be fully dark. As a result, uniform illumination occurs over a wide area.

4. When one slit is lit with red light and the other with blue light, no interference pattern appears on the screen.

• Path difference:

The path difference between interfering waves that collide at point P on the screen is given by

where x be the position of point P from central maxima

For maxima at P:

And for minima at P:

• Diffraction of Light

The phenomenon of light bending around the corners of an obstacle/aperture with a size equal to the wavelength of light.

## Types of Diffraction

 Fresnel diffraction Fraunhofer diffraction Either the source or the screen, or both, are at a finite distance in Fresnel's diffraction Both the source and the screen are effectively at an infinite distance from the diffracting device in this situation. The source or screen, or both, are at a finite distance from the diffracting apparatus in Fresnel's diffraction. Diffraction at a single slit, double slit, and diffraction grating are all common instances.

## Comparison Between Interference and Diffraction

 Interference Diffraction The superposition of waves from two coherent sources produces this effect. The superposition of wavelets from different portions of the same wavefront produces this effect. All fringes are of the same width Although all secondary fringes are the same width, the centre maxima is twice as wide. All fringes have equal intensity Intensity decreases as the order of maximum increases. Path difference for maximaPath difference for minima For secondary maximaPath difference for minima

• Unpolarized light:

Unpolarized light is light that has electric field oscillations in all directions in a plane perpendicular to its propagation. The horizontal and vertical components of light oscillation are separated.

• Polarized light:

Plane or polarized Polarized light is light that has just one plane of oscillations.

The plane of oscillation is the plane in which polarized light oscillates.

The plane perpendicular to the plane of oscillation is the plane of polarization.

Light can be polarized by passing through particular crystals like tourmaline or Polaroid.

• Polarization by Scattering:

When a beam of white light is transmitted through a material with particles of the same size as the wavelength of the light, the beam is scattered. This scattered light will propagate perpendicular to the incidence direction and will be plane-polarized (as detected by the analyzer). This is known as scattering polarization.

## Polarization of Light by Reflection

When a beam of white light is transmitted through a material with particles of the same size as the wavelength of the light, the beam is scattered. This scattered light will propagate perpendicular to the incidence direction and will be plane-polarized (as detected by the analyzer). This is known as scattering polarization.

• Polaroid:

A Polaroid is the name of the device that produces plane-polarized light. It is based on the selective absorption principle. It's also more powerful than the tourmaline crystal.

A thin layer of ultramicroscopic quinine iodo sulphate crystals with optic axes parallel to one another is also known as it.

Only light oscillations that are parallel to the transmission axis can travel through a Polaroid.

Unpolarized light is incident on a polarizer, which is a crystal or Polaroid. An analyzer is a crystal or polaroid on which polarized light is incident.

## Malus Law

The square of the cosine of the angle between the analyzer’s plane of transmission and the plane of the polarizer will vary the intensity of polarized light passing through an analyzer. This is referred to as the Malus law.

• Brewster’s law

When unpolarized light is reflected from a clear medium (with refractive index=μ), the reflected light will be totally plane-polarized at a specific angle of incidence (known as the angle of polarization θp). Brewster's law is the name for this rule.

• RESOLVING POWER:

If two-point objects are near together, their image diffraction patterns will likewise be close together and overlap.

The minimum distance between two objects that can be seen independently by the object instrument is known as the instrument's limit of resolution.

• Resolving power of Microscope:

R.P. of microscope =

• Resolving power of Telescope:

R.P of telescope =

Where D is the aperture of the telescope

## Significance of NCERT Class 12 Physics Chapter 10 Notes

• NCERT Wave Optics class 12 notes are essential for comprehending wave phenomena.
• These class 12 physics chapter 10 notes provide a comprehensive review of the chapter's main topics.
• They are beneficial for CBSE Class 12 board exams because they correspond to the CBSE Class 12 Physics Syllabus.
• CBSE class 12 physics ch 10 notes also serve as valuable resources for competitive exams such as VITEEE, BITSAT, JEE Core, NEET
• The ch 10 physics class 12 notes provide a condensed version of the main concepts, making it easier for students to review and comprehend the material.
• Physics class 12 chapter 10 notes pdf, which allows for offline study and convenient access.

### NCERT Class 12 Notes Chapterwise

 NCERT Class 12 Physics Chapter 1 Notes NCERT Class 12 Physics Chapter 2 Notes NCERT Class 12 Physics Chapter 3 Notes NCERT Class 12 Physics Chapter 4 Notes NCERT Class 12 Physics Chapter 5 Notes NCERT Class 12 Physics Chapter 6 Notes NCERT Class 12 Physics Chapter 7 Notes NCERT Class 12 Physics Chapter 8 Notes NCERT Class 12 Physics Chapter 9 Notes NCERT Class 12 Physics Chapter 10 Notes NCERT Class 12 Physics Chapter 11 Notes NCERT Class 12 Physics Chapter 12 Notes NCERT Class 12th Physics Chapter 13 Notes NCERT Class 12th Physics Chapter 14 Notes

### NCERT Books and Syllabus

 NCERT Book for Class 12 NCERT Syllabus for Class 12

### Frequently Asked Question (FAQs)

1. What are the main derivations covered in the wave optics class 12th notes.

The ncert notes for class 12 physics chapter 10 do not include any derivations. This NCERT note provides a summary of the chapter's main themes and equations and can be used to review wave optics.

2. What is the Interference of Light?

Interference of light is explained in ncert class 12 physics chapter 10 notes. The interior and outside of an item refract light, causing this phenomenon. The reflecting surfaces might be parallel or interconnected. When it comes to light that reflects from the outside, this can be both beneficial and harmful according to wave optics class 12 notes

This is feasible because light travels when waves are generated on the inner and outer surfaces, resulting in colour. In addition, the vibrant colours of those wavelengths are included. As reflected light is cancelled in places where the waves are out of phase, destructive interference ensues.

3. What is Diffraction?

According to CBSE class, 12 physics chapter 10 notes Diffraction is a technique for bending light waves around the edges of a barrier or opening. These phenomena can occur in almost every wave type. This occurrence is possible, according to the Huygens-Fresnel Principle and the principle of superposition of waves. The Huygens-Fresnel Principle states that every point on a wavefront is a wavelet's source. These wavelets scatter out in a forward direction equal to the speed of the originating wave.

Furthermore, the wavelets' tangent line is a new wavefront. At the same time, the concept of superposition states that the sum of incentives at any instant is the net outcome of numerous stimuli.

4. What is the Doppler effect as obtained from wave optics class 12 notes pdf download?

The apparent frequency of the light received by the observer differs from the real frequency coming from the source of light if and when there is relative motion between the observer and the source. The Doppler effect in light is the name for this phenomenon. The effect can be used to determine how fast an item is approaching or retreating.

5. Is Wave Optics class 12 notes important for JEE?

Yes, Wave Optics Class 12 notes are important for JEE preparation as they cover essential topics aligned with the JEE syllabus, helping students to grasp key concepts and excel in the exam.

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