Today I’m going to share with you the Wave Optics Class 12 Handwritten Notes PDF which you can download for free using the direct download link given below.
Wave Optics is one of the important chapters of class 12 physics subject. This chapter is also very important for the JEE and NEET exams. If you are studying in class 12th or are preparing for JEE or NEET, then the Wave Optics notes are going to be very helpful for you. Taking that point I am going to share the complete handwritten notes on wave optics in PDF format.
Wave Optics Handwritten Notes And Important Topics PDF Free Download
Important topics from Wave Optics for boards are wavefront, coherent source, Huygens principle, Snell’s law, magnification, lens maker formula, Maula’s law, Young’s experiment, single slit experiment, Brewster law, Polarised and unpolarized light, telescope and prism.
Wave Optics Class 12 Handwritten Notes PDF Overview
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Class 12 Physics Handwritten Notes
Wavefront:
It is the continuous location of all the particles of the medium which are vibrating in the same phase of oscillation at any given time.
Depending on the size of the light source, the wavefronts take on different shapes.
(i) plane wavefront
(ii) circular wavefront
(iii) cylindrical wavefront
Rays: Rays are arrows perpendicular to the wavefront in the direction of propagation of the wave.
Time took: The time taken by the light to travel from one wavefront to the other is called the time taken by the beam.
Huygens’ principle:
According to Huygens each point on a given wavefront (called the primary wavefront) acts as a new source of new perturbations, called secondary wavefronts, which travel all the way with the velocity of light in the given medium. travels in different directions.
The surface touching these secondary waves, at any instant in the direction ahead of the tangent, gives a new wavefront at that instant. These are called secondary wavelets.
Principle of Huygens’ Construction:]
It is based on the principle that each point on the wavefront is the source of a secondary wavefront.
The envelope of these wavefronts i.e. the surface tangent to all the secondary wavefronts gives the new wavefront.
Snell’s law of refraction [Snell’s law of refraction:]
Reflection of plane waves using Huygens’ principle: The law of reflection (i = r) can be derived using the wave principle.
Refraction of plane waves using Huygens’ principle: Snell’s law of refraction can be derived using the wave principle. Huygens’ Principle (where v1 and v2 are the speed of light with refractive index in media 1 and 2 respectively).
Relation between frequency and speed: Frequency remains the same as light travels from one medium to another. The speed of a wave v is given by
v=fraclambdaT
The wavelength of the wave is lambda and T=1/v is the period of oscillation.
Doppler Effect: Whenever there is relative motion between the source and the observer, the apparent frequency of the light received by the observer differs from the actual frequency emitted by the source of light. This effect is called the Doppler effect in the light. The effect can be used to measure the speed of an approaching or receding object.
Change in frequency: for a source moving away from the observer, and for a source moving towards the observer. , is the change in frequency
Coherent and Incoherent Addition of Waves:
Coherent source:- Two sources of light that emit light waves of the same frequency (or wavelength) continuously with zero or constant phase difference between them are called coherent sources.
Incoherent sources:- Two sources of light that do not emit light waves with a constant phase difference are called incoherent sources.
The total intensity I am not just the sum of the individual intensities I1 and I2 due to the two sources but also includes an interference term-
The interference term averaged over several cycles is zero if sources have different frequencies or The sources have the same frequency but no constant phase difference.
According to the superposition principle, when two or more wave motions traveling through a medium superimpose each other, a new wave is formed in which the resultant displacement due to the separate waves at that instant is class 12. physics chapter 10
The average of the total intensity will be physics class 12 notes ncert phi is the inherent phase difference between two superimposing waves.
The importance is that the intensity of two sources of light is not equal to the sum of the intensity due to each of them.
The resulting intensity depends on the relative location of the point from the two sources, as changing it changes the path difference as we move from one point to the other.
As a result, the resulting intensity will vary between maximum and minimum values determined by the maximum and minimum values of the cosine function. these will be
Young’s Experiment
Two parallel and very close slits S1 and S2 (illuminated by another narrow slit) behave like two coherent sources and produce a pattern of dark and bright bands on a screen known as interference fringes.
Path difference for a point P on the screening Experiment
where d is the distance between the two slits, D is the distance between the slits and the screen, and x is the distance from the central fringe to the point P.
For constructive interference (bright bands), the path must be an integer multiple of the difference, i.e., the separation between adjacent bright (or dark) fringes, which can be measured using
Young’s double slit interference experiment: fringe width, eta = Dlambdaoverd
where D is the distance between the slits and screen d is the distance between the two slits
Constructive Interference:
Phase Difference: Constructive Interference: where n is an integer
path difference: class 12 physics notes where n is an integer
Destructive interference:
phase difference: Destructive interference where n is an integer
Path difference: Destructive interference, where n is an integer.
intensity distribution curve for interference
Interference fringes with white light: – When the fringes are illuminated with white light, the interference pattern consists of a central white fringe with some colored fringes on either side and then a normal illumination.
Conditions for continuous intervention:-
(i) The two sources of light must be coherent.
(ii) The frequencies (or wavelengths) of both waves should be the same.
(iii) Light should be monochromatic.
(iv) The amplitudes of the interfering waves should be equal or nearly equal.
(v) The two sources should be narrow.
The phenomenon of bending of light around the corners of an obstacle is called the diffraction of light.
Diffraction due to single slit:
The single-slit diffraction pattern shows central maximum, zero intensity at angular separation Wave Optics Class 12 Notes.
Angular spread of the central maxima
Width of the central maxima
Where D is the distance of the slit from the screen, d is the width of the slit.
Position of minima on either side of the central maxima: central maxima,, where n = 1,2,3,….
The relation between phase difference & path difference
is the phase difference and DeltaX is the path difference.
Different parts of the WaveFront at the Slit act as Secondary Sources:]
The diffraction pattern is the result of interference of waves from these sources.
The intensity plot looks like this, with a bright central maximum followed by smaller intensity secondary maxima, with points of zero intensity in between, whenever
Different Parts of the WaveFront at the Slit act as Secondary Sources
The width of the central maximum is directly proportional to the wavelength of the light and inversely proportional to the width of the slit.
Emission, Absorption, and Scattering:
These are the three processes by which matter interacts with radiation. In emission, an accelerated charge radiates and loses energy.
In absorption, the charge gains energy at the expense of the electromagnetic wave.
In scattering, the charge accelerated by the incident electromagnetic wave radiates in all directions.
Wave Optics Class 12 Notes: Polarization
If the vibrations of a wave exist only in one direction in a plane perpendicular to the direction of propagation, the wave is said to be polarized or plane polarized. The phenomenon of confining the oscillations of the wave to only one direction in the transverse plane is called polarization of the wave.
When light passes through a single polaroid P1, the intensity of the light is halved, independent of the orientation of P1. When a second polaroid P2 is also included, at a specific orientation w.r.t P1, the net transmitted intensity becomes zero but becomes fully transmitted when P1 is 900 from that orientation. This happens because the polarization transmitted by the polaroid has a component of E parallel to its axis.
Polarizer: A device that polarizes the unpolarized light passed through it is called Polarizer.
Unpolarized sunlight scattered by the atmosphere or reflected from the medium becomes partially polarized.
Optical Activity: When plane-polarized light passes through a certain material, the plane of polarization of light is rotated by a certain angle about the direction of propagation of light. This phenomenon is called optical activity or optical rotation and optically active matter.
The intensity of light due to polarization (Malus’s law):
where I am the light intensity after polarization, Io is the original intensity, is the angle between the analyzer and the axis of polarization
A graph between the intensity of light transmitted by the analyzer and the angle between the polarizer and the analyzer will be shown-
Methods of producing plane-polarized light:
reflection
scattering
double refraction
Polarization by reflection (Brewster’s Law): When unpolarized light is incident on a transparent surface at the polarizing angle, the reflected light with its electric vector perpendicular to the plane of incidence when the refracted and reflected rays make a right angle with each other Huh. ,
Polarization by Scattering:
A scattering of light occurs when it encounters a particle of the same size as its wavelength. The scattering of sunlight by dust particles is an example of polarization by scattering.
Polarization by double refraction: When an unpolarized ray passes through some crystal like quartz or calcite, it splits into two rays. This phenomenon is called double refraction.
Rayleigh showed that the scattering of light is proportional to the fourth power of the frequency of light. . Hence blue light is scattered more than red. This explains the blue color of the sky.
Polaroid: Polaroids are thin commercial sheets that use the property of selective absorption to produce an intense beam of plane-polarized light.
Use of Polaroid – in sunglasses and camera filters, windscreens, window panes of airplanes, LCDs, etc.
Wave Optics Handwritten Notes
Introduction to the wave nature of light
Light is a type of electromagnetic radiation. Light is such an integral part of our daily lives that we cannot imagine living without it. During the day, we get light from the Sun, which is the natural source of light. At night when we are deprived of sunlight, we have developed many artificial sources of light so that our work can continue even at night. Light produces the sensation of sight through the eye. Production of chemical reactions in photographic films and plates and photosynthesis in plants etc. prove that light is a form of energy like heat.
some defined words
luminous objects
Those substances which emit light on their own are called luminous substances. Like the Sun, stars, white-hot filaments of electric bulbs, etc.
Non-luminous objects
Those objects which do not emit light on their own are called luminous objects. Unilluminated objects can be seen only in the light. Example- pen, table chair, etc. Objects are divided into three categories on the basis of their ability to allow light to pass through them-
1. Transparent Objects:
Those objects through which light passes are called transparent objects. We stand on one side of these things, we can see things on the other side. Example- glass, water, etc.
2. Opaque Objects:
Those objects, through which light cannot pass, are called opaque objects. These objects either reflect or absorb light, but do not allow the rays of light to go to the other side by penetrating themselves. Standing behind these things, we cannot see the things on the other side.
Examples- Iron sheets, thick wooden cardboard, etc.
3. Semitransparent Objects:
These are the objects which allow some amount of light to pass through them and either reflect or absorb the remaining part. Due to the cover of these objects, the objects on the other side look blurred.
Examples- are wax paper, oil paper, etc.
shadow formation
One property of light is that it travels in a straight line. Due to traveling in a straight line, when an opaque object comes in front of the light and does not allow the light to pass through itself in a straight line, then the light gets reflected, or is absorbed by that object, as a result of this action In the direction of movement of light behind that object, a dark shape of that object is formed, which is called shadow or reflection.
shadow
The total shadow is called the shadow. The source of light is not visible from the shadow.
penumbra
Partial shadow is called the penumbra, from here the rays of light are partially visible. Due to the movement of light in a straight line, the activities of lunar eclipses and solar eclipses also take place.
photometry
The branch of physics under which the measurement of the illumination capacity of a light-producing object is discussed.
luminous flux
The amount of light that is radiated from a light source or illuminated surface in one second is called luminous flux. It is that part of the total radiated light that is visible and affects the eye.
luminance intensity
The amount of light energy incident per second on a unit area of a surface is called light intensity.
luminescence efficiency
It is the amount of incident light energy per second per unit area of a surface, which is obtained by keeping the surface at a unit distance and the rays of light normally falling on that surface.
Photo
It is a unit of luminous intensity, equal to one lumen per square centimeter.
photometer
It is a device that is used to compare the illuminance of two sources of light. Rumford photometers and Bunsen’s Greise spot photometers are commonly used.
reflection
When the rays of light fall on a mirror or other similar shiny surface, they return again in a certain direction of the same medium through which they have come according to the following rules. This phenomenon is called the reflection of light. The motorist uses a concave mirror to see the scenery behind him – because the concave mirror produces small images of objects, due to which a large field of view is visible and the motorist can see many objects behind the car. Can see Along with this, there is no reflection of the sun’s rays on it because the sun’s rays diverge and get scattered. That is why the motorist uses this mirror.
Laws of reflection-
1. The angle of incidence and the angle of reflection are equal.
2. The incident ray, the reflected ray, and the normal drawn at the point of incidence, all three on the same plane; Live in point.
focus
The point at which the rays of light reflected from the mirror either actually converge or appear to diverge from that point.
focal length
The distance between the pole and the focus of the mirror is called the focal length.
parallax
When looking at one side of the lines joining two objects, the relative displacement between the two objects is known as parallax.
Example- While traveling by train the earth appears to rotate. This is due to parallax. When the train is in high speed, then the distant objects like houses, trees, etc. seem to be moving in the direction of the velocity of the train, and the objects on the side of the track seem to be moving in the opposite direction. This makes it seem as if the earth is rotating.
Smoky metal ingot appears shiny when immersed in pure water – Smoky metal ingot appears shiny when immersed in water, because the carbon particles of the smoke are coarse, around which air troughs are formed. Huh. Rays of light traveling through a metal body pass through two dissimilar mediums, water, and air present in the trough, which undergo total internal reflection. Due to the total internal reflection of light, the metal body appears shiny.
refraction of light
When rays of light pass from one transparent medium to another transparent medium, they are bent towards or away from the normal drawn in the medium at their point of incidence. This phenomenon is called the refraction of light.
dispersion of light
When a beam of white light passes through a triode, its constituent colors are scattered, this is called dispersion of light. Its shadow formed on the screen is called Varnapat. The regions of the spectrum are both visible and invisible. There are seven colors in the spectrum – violet, blue, indigo, green, yellow, orange, and red. The rays of blue color have the maximum deviation and the rays of red color have the least deviation.
The deviation of red color is minimum in the spectrum of white light formed by the prism – because there are seven colors in the spectrum of light formed by the prism. These seven colors are deflected in the form of a band because the wavelengths of the colors are different. The refractive index of violet color is highest and that of red color is lowest. Therefore, the deviation of violet color is maximum and that of red color is minimum.
spectrum
There is a combination of seven colors (VIBGYOR) in the rays of white light. When these rays are projected onto a triangle, the rays are deflected in the form of a band of the above-mentioned colors. The wavelengths of the colors are different, which makes up the color palette. This band of colors is called the spectrum. The white light of the Sun is a mixture of seven colors. These colors have different wavelengths. A ray of light falls on the dust particles floating in the air and the dust particles scatter the rays of light. Blue color, being of short wavelength, gets scattered in the sky. This is the reason why the color of the sky appears blue.
Rainbow
A rainbow is a good example of reflection of light, total internal reflection, and dispersion. All these activities require a suitable medium.
After the rain, the raindrops stuck on the dust particles present in the air act as this medium. The raindrops act as a trifle, which scatters the seven constituent colors of light in the form of a spectrum. This is the reason why the rainbow appears only after rain.
Lens
The lens is a transparent and refractive medium made of two spherical surfaces or one spherical and the other flat surface, which is usually made of glass. There are mainly two types of tails – the concave and the concave; the middle surface of the tala is raised and that of the tala is flat. Generally, six types of lenses are used-
1. Double convex lens – Both the surfaces of this lens are convex.
2. Concave lens – One surface of this lens remains flat and the other emerges.
3. Concave lens – The surface of this lens is thin in the middle and the other is raised.
4. Double Concave Lens – Both the surfaces of this lens remain tapered in the middle.
5. Equi-concave lens – One surface of this lens remains flat and the other is tapered.
6. Advanced-concave lens – One surface of this lens bulges and the other surface remains flattened.
The first three lenses are called converging and the last three lenses are called diverging.
infrared rays
There is invisible radiation on both sides of the visible spectrum, which does not produce a visual sensation. The radiation that lies outside the red end of the visible spectrum is called infrared radiation. Its wavelength is up to 4000,000 A, but its frequency is small.
Use
1. Infrared radiation is used to measure the wavelength of radiation.
2. Wind or thick fog cannot absorb infrared radiation. Infrared photographs can be taken from a great distance even in thick fog.
3. It is also used in the field of medicine and industry. Infrared radiation penetrates inside the human body and dilates the blood vessels, which increases the flow of blood.
ultraviolet rays
Radiation up to 100 Å wavelength outside the violet end of the visible spectrum is called ultraviolet radiation. Sunlight contains enough ultraviolet rays. Electric arcs of carbon, iron, or other metals, mercury vapor lamps, are artificial means of obtaining ultraviolet light. Usage- The room where blood plasma, medicine, vaccine, etc. are prepared and kept in vessels is sterilized with ultraviolet rays. Medicines, poisons, colors, etc. become fluorescent due to the effect of ultraviolet rays. The resolving power of the microscope increases when ultraviolet rays are used for light. Fluorescent tubes are designed on the basis of fluorescence produced by ultraviolet radiation.
object color
original color
Blue, green, and red are the basic colors. Other colors are prepared by mixing these three colors in proper proportion. The base color cannot be created by mixing other colors. Mixing these basic colors in equal proportion makes white color. Peacock blue is made by mixing blue and green. Magenta is obtained by mixing red and blue colors. Similarly, the yellow color is formed by mixing green and red. These colors are called complementary colors. If these three complementary colors are mixed in equal proportion, then white color is formed from them.
Indigo is put in the cloth because after washing the cloth becomes yellow, indigo is offered to remove the yellowness. Yellow and blue are complementary colors that combine to produce white. This is the reason why clothes turn white after indigo. The light blue powder is mixed in washing powders like Surf, Sway, etc.
Color of the object; 1. Depends on reflected light and transmitted light.
complementary color
If the white color is obtained by the combination of two colors, then these two colors are called complementary colors.
1. Red and Peacock Blue
2. Blue and Yellow
3. White color is obtained by mixing green and magenta colors. These colors are called complementary colors.
reflected light
In daily life, we see an object and say that such and such an object is of such and such color. But, according to scientific analysis, the color of an object – green, yellow, blue, etc. – is the color of the light reflected by that object. The white light of the Sun is a combination of seven colors. Out of these seven colors, the color which the object reflects is the same color it appears. When an object appears yellow in sunlight, it means that it reflects yellow, a component of sunlight, and absorbs the remaining six colors. The object appears black, which means the absorption of all the seven constituent colors of the Sun by the object, not the reflection of any color. On the contrary, the object appearing white means the reflection of the seven component colors by the object, not the absorption of any color.
daylight; In white light, green leaves appear green, but in red light; black-green leaves appear green in the white light of the day because it is able to reflect only green, the rest of the colors, out of the seven constituent colors of white light from the Sun. absorbs When the red light is incident on it, it completely absorbs red color and does not reflect any light, hence it appears black in red light.
It is a matter of natural light, in which there is a combination of seven colors – violet, blue, indigo, green, yellow, orange, and red. In artificial light red, yellow, blue, etc. only the color of which it appears remains.
The color of the object reflects the same color and absorbs the different colors. So when red light falls on a yellow object, it absorbs red light and does not reflect any color. Hence the object appears black in red light. But when yellow light falls on a yellow object, it reflects yellow light, due to which that object looks yellow.
The stars twinkle
The layers of the atmosphere have different densities and their temperature also varies due to transport currents. The refractive index of light depends on the density and temperature of the medium. The rays of light coming from the stars pass through different layers of the atmosphere and at different temperatures to reach the earth. This is the reason why the path of light keeps on changing due to the change in refractive index.
As a result, the rays of light do not always fall on the same spot on the earth and the stars appear to glow intermittently, which is called the twinkling of stars.
Mirage
It is a type of optical illusion caused by the total internal reflection of light. The refractive index of an object also depends on the temperature of the object, so the refractive index of hot air is lower than that of cold air. In summer, the air near the surface of the earth is hotter. As the height from the surface of the earth increases, the air becomes cooler. Therefore, many layers of air are formed which act as both dense and rarefied mediums. Rays of light traveling from the upper end of an object enter the rarer medium from the denser medium and run away from the perpendicular according to the law of refraction. Ultimately, such a situation also comes, when the rays of light do not enter the rare medium and return to the dense medium, and an inverted image of the object is formed, the type of image seen in a water source. Thirsty creatures in the desert roam here and there in the illusion of this water source during summer, which is called Mrig Marichika.
summary
1. Light is a type of electromagnetic radiation.
2. Polarization of light waves is possible.
3. Due to the movement of light in a straight line, the activities of the lunar eclipse and solar eclipse also take place.
4. Photometer is an instrument that is used to compare the illuminance of two sources of light.
5. Laws of reflection-1. The angle of incidence and the angle of reflection are equal. 2. The incident ray, the reflected ray, and the normal drawn at the point of incidence, all three lie in the same plane.
6. Laws of Refraction – There is a definite ratio between the sine of the angle of incidence and the sine of the angle of refraction for any two media. 2. The incident ray, the refracted ray, and the normal at the point of incidence, all three lie in the same plane.
7. The refractive index of a diamond is 2.42 and the critical angle is 24.40. The surface of a diamond is cut in such a way that the rays of light entering its surface are completely reflected several times. Inside a diamond, the angle of incidence that a ray of light striking its surface makes is greater than 24.40. Because of the many total internal reflections within a diamond, it appears shiny.
8. When a beam of white light passes through a prism, its constituent colors are scattered, this is called dispersion of light.
9. The rays of blue color have the maximum deviation and the rays of red color have the least deviation.
10. Lens is a transparent and refractive medium made of two spherical surfaces or one spherical and the other flat surface, which is generally made of glass.
11. The wavelength of infrared radiation is up to 4000,000 A, but its frequency is small.
12. Radiation up to 100 Å wavelength outside the violet end of the visible spectrum is called ultraviolet radiation.
13. Blue, green, and red are the basic colors, other colors are prepared by mixing these three colors in proper proportion.
14. Light travels in a straight line.
15. Light waves travel faster in the ether because ether is weightless. Its density is very low and its elasticity is very high.
16. Huygens’s theory of secondary wavelets can explain the reflection of light, the laws of refraction, and the interference and diffraction of light. And the photoelectric effect cannot be explained by this theory.
17. In the event of refraction, the speed of the wave and the value of wavelength change while the frequency of the wave does not change.
18. The speed of light in water is less than the speed of light in air. Because the refractive index of water is more than the refractive index of air.
19. The shape of interference fringes is hyperbolic.
20. The interference fringes may or may not be of the same width. But the width of the diffraction fringes can never be the same.
21. The phenomenon of polarization occurs only in light, the phenomenon of polarization does not occur in sound.
22. Polaroid converts unpolarized light into polarized light.
23. A man needs a mirror of half his height to see his full image.
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