 I like to teach people,my favourite subject  physics and math.I enjoy cricket ,tour

Rajesh Kumar

sound wave concept, Longitudinal and transverse waves. Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves. It requires a medium to propagate. Through solids, however, it can be transmitted as both longitudinal waves and transverse waves.Laplace correction and Newton's assumption. calculations of speed of sound wave.

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CBSE Class 11

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(Hindi) Sound wave

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CBSE (Central Board of Secondary Education)

Overview of sound wave course details.Longitudinal and transverse waves. Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves. It requires a medium to propagate. Through solids, however, it can be transmitted as both longitudinal waves and transverse waves.

Sound Wave Course Overview (in Hindi)

Nature and propagation of sound wave. Ultrasonic,  infrasonic and audible frequency of sound wave. Compression and rarefaction creation in sound wave.

Nature and Propagation of Sound Wave (in Hindi)

Wavefront: a surface containing points affected in the same way by a wave at a given time.displacement wave & pressure wave:  If the particles at a given point fluctuate following a sine, the pressure there fluctuates like a cosine, 90 degrees out of phase with the displacement.relationship between pressure amplitude and displacement amplitude.

Wavefront, displacement Wave and Pressure Wave (in Hindi)

Speed of Sound Wave in Material Medium (in Hindi)

Calculation of speed of sound wave in solid and gases. Newton's assumption and Laplace correction.

Speed of Sound Wave in Solid and Gases (in Hindi)

Effect of pressure,  temperature and humidity on the speed of sound in air. Nemerical based on this topic. Mathematical calculations of variation in temperature related to speed of sound in air.

(Hindi)Effect of pressure, temperature and humidity on the speed of sound in air

Intensity of sound wave defined by average power crossing per unit area. Watt/meter2.intensity directly related to average energy passing through space from one point to other point. I proportional to square of pressure amplitude (p०).A sound wave's amplitude relates to changes in pressure. The sound is perceived as louder if the amplitude increases, and softer if the amplitudedecreases. ... The average amount of energy passing through a unit area per unit of time in a specified direction is called the intensity of the wave.

(Hindi) Intensity of sound wave

Characteristics of sound wave. The sound waves cause the eardrum to vibrate. Three basic character peach loudness and quality peach depends on frequency loudness depends on intensity and quality depends on waveform.

(Hindi) Appearance of sound to human ear

Interference of sound wave. Interference of Sound. Two traveling waves which exist in the same medium will interfere with each other. If their amplitudes add, the interference is said to be constructive interference, and destructive interferenceif they are "out of phase" and subtract.What are the effects of constructive and destructive interference in sound?interference of sound waves from two speakers. 
interference of sound waves from two sources.two wavesources are perfectly coherent if they have a constant phase difference and the same frequency, and the same waveform

(Hindi) Interference of sound wave

Reflection of sound wave. The reflection of sound follows the law "angle of incidence equals angle of reflection", sometimes called the law of reflection.The reflected waves can interfere with incident waves, producing patterns of constructive and destructive interference. This can lead to resonances called standing waves in rooms. 
It also means that the sound intensity near a hard surface is enhanced because the reflected wave adds to the incident wave, giving a pressure amplitude that is twice as great in a thin "pressure zone" near the surface.

When sound waves in air (pressure waves) encounter a hard surface, there is no phase change upon reflection. That is, when the high pressure part of a sound wave hits the wall, it will be reflected as a high pressure, not a reversed phase which would be a low pressure. 
A positive or "high" pressure is one that is above the ambient atmospheric pressure and a negative or "low" pressure is just one that is below atmospheric pressure. 
A wall is described as having a higher "acoustic impedance" than the air, and when a wave encounters a medium of higher acoustic impedance there is no phase change upon reflection.

On the other hand, if a sound wave in a solid strikes an air boundary, the pressure wave which reflects back into the solid from the air boundary will experience a phase reversal - a high-pressure part reflecting as a low-pressure region. That is, reflections off a lower impedance medium will be reversed in phase.

(Hindi) Reflection of sound wave

Vibrations of air column in closed organ pipe.The organ pipes produce sound from the vibrations of standing waves in a columnof air with in a pipe or tube.A vibrating tuning fork of frequency n is held near the open end of the tube.Closed cylindrical air column will produce resonant standing waves at a fundamental frequency and at odd harmonics. The closed end is constrained to be a node of the wave(displacement wave)  and the open end is of course an antinode. This makes the fundamental mode such that the wavelength is four times the length of the air column.

Organ pipes are musical instruments which are used to produce musical sound by blowing air into the pipe. Organ pipesare two types (a) closed organ pipes,closed at one end (b) open organ pipe,open at both ends.

v(frequency of vibrations of air column) = (2n+1) u/4l, where n=0, 1,2... Only odd harmonics present.

(Hindi)Vibrations of air columns in closed organ pipe

Vibrations of air column in open organ pipes. All harmonics present in open organ pipes. Standing wave set up by the interference of twice reflected wave and new incoming wave from source at near source open end. path difference of twice reflected wave with respect to new one is Delta  is equal to 2pi/lambda x2l. For constructive interference phase difference is equal to 2 n Pi. Now amplitudes keeps on growing and finally standing wave are set up. Energy lost by various dancing effects equals the energy input from the source first resonant frequency is equal to speed divided by 2L. And length of tube is equal to Lambda /2.

For n=1, fundamental frequency found and for n is equal to 2 to first overtone or second harmonics observe. 
For n is equal to 3 second harmonics or third harmonics observe. In open organ pipe all harmonics present.

(Hindi) Vibrations of air column in open organ pipe

Practically calculate the speed of sound in air. By resonance column method.

(Hindi) Determination of speed of sound in air,Resonance Column Method

Kundt's Tube Experiments to find speed of sound in gas and rod.
Kundt's experiment to find speed of soundwave in gases and in metal rod. In this experiment  uses principle of standing wave, nodes, antinode and wavelength by using gas filled in cylindrical tube. both end of the tube close by rod mounted disc and movable piston .disc mounted Road and in the centre of earth clamping done longitudinal waves from rodto  resonance tube movable piston so adjusted so  that standing wave setup and the resonance happen. frequency of longitudinal wave is equal to the resonance frequency by knowing /measuring the length of heap of powder. we calculate wavelength of wave now we can calculate speed of sound wave in gases.

(Hindi)Kundt's tube experiment speed of sound in gas and rod

When two sound waves of different frequency approach your ear, the alternating constructive and destructive interference causes the sound to be alternatively soft and loud - a phenomenon which is called "beating" or producing beats. In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies.when the two waves are nearly 180 degrees out of phase the maxima of one wave cancel the minima of the other, whereas when they are nearly in phase their maxima sum up, raising the perceived volume.

BEATS

Diffraction property of sound wave. Bending of sound wave. Wave spread in medium or in space when wave created by vibrating source if medium is homogenous and isotropic then wavefront of point source is spherical wave, at long distance this wavefront became plane wave. shape of wave change when meets an obstacle or opening in its path bending of the wave around the edge from an obstacle or an opening is called diffraction . when plane wavefront passed through a pinhole then it becomes a spherical wavefront and pinhole behave like point source. diffraction is a characteristic property of wave motion and all kinds of waves exhibit diffraction. condition: dimension of obstacle opening comparable or smaller than the wavelength of the wave, d less than or equal to wavelength. If d >wavelength diffraction effects are almost negligible if dimension of the opening obstacle greater than the wavelength of the wave. Frequency of the audible sound range 20Hz to 20 kilohertz, speed of sound in air 332 m per  second then wavelength of audible sound greater than 1.6 cm and less than 16 m. for audible sound normally obstacles are opening have small dimensions so d diffractions normally observed for daily life for sound wave. Wavelength of light less than sound wave, so diffraction is more in longer wavelength .so diffraction easily observe in sound wave. sound wave travel around corners this is example of diffraction.

Diffraction of sound wave

Doppler Effect related by Apparent frequency change in frequency due to relative motion between source and observer. there are four conditions here I discussed in this lesson. first of all relative motion of source with respect to medium .source moving towards observer and source moving away from observer. second conditions observer moving towards source and observer go away from the source . the relative motion between source and observer always given with respect to medium .dopller  effects also relate with Pitch .when train approaches the platform  the person or the receiver received high pitch. and when  train passes through and go away from the observer the observer receives sudden fall in the loudness and pitch.  Doppler Effect clearly defined or related to the Apparent frequency which is due to the relative motion of source or observer with respect to medium in the case of Doppler Effect Apparent frequency is equal to Wave velocity + velocity of observer divided by speed of wave - speed of source .when source moving  towards observer then we take positive sign and when source or observer go away then this then we take negative sign.

Doppler effect in sound wave.

Change in wavelength,  Sonic Boom 
and Mach Number. 
Change in wavelength is observed when  speed of source with respect to medium and observer consider in rest. then the Apparent frequency observe apparent  frequency is equal to the speed of sound in air Plus speed of observer divided by speed of sound in air minus speed of source whole x natural frequency .new wavelength after solving these equations with speed of source is equal to U, we can calculate change in wavelength Lambda this is equal to speed of sound in air - speed of source ,divided by speed of sound in the ear hole X wavelength. difference between two maximum is change in wavelength. when lambda  constant then concentric spherical wavefront created. when a speed of source is 'u' then no any concentric wavefront . all circles are different is wavefront having its centre at the position where the source is situated .preceeding wavefront will exceed the next one by an amount 'Vxt ' the spacing between the successive difference decrease along the direction of motion and increases on the opposite side. this separation being the new balance the change in wavelength due to the motion of the source .
'Sonic boom' subsonic velocities less than speed of sound in air. Supersonic velocities greater than a speed of sound in air. Supersonic plane travel in medium emmit cracking sound.  known as sonic boom. a spherical wavefront intersect over the surface of a cone with the apex at the source. due to constructive interference of a large number of waves arriving at the same instant on the surface of the cone. pressure waves of a very large amplitude are sent with the conical wavefront. such waves are also called 'shock waves' .
the ratio of speed of source and speed of sound in air is called ' Mach number when both the speed = then speed of source is called one Mach

Change in wavelength, Sonic Boom and Mach Number

Definition of musical scale , reverberation time, echo generation, accoustic of building. Musical scale is a sequential pattern of frequencies which is pleasant to hear. Acoustic of building covered design of auditorium parabolic background .sound absorbing materials used. reflections of sound and direct sound create  Eco. when Eco last long then this phenomenon of known as reverberation and the time duration  is known as reverberation time then such sound is called reverberant sound. ringing is a phenomenon of amplifying sound from sound box which is unpleasant .minimum distance to hear Eco the distance of wall from observer is 17.2 m.

Musical scale, acoustic of building, Reverberation Time, Echo

Numerical based on sound wave. Total 04 numerical solved in details. A small source of sound moves on a circle as shown in figure and an observer is sitting at o .let n1,n2,n3 be The frequencies heard when the source is at A ,B and C respectively.

Numerical exercise no 01, based on sound wave

Numerical based on sound wave. Objective question and detailed solutions.

Numerical exercise no 02

Through Unacademy , want to reach out to students...those who really needs me.
Trying to help how to learn basics with simple tricks .

Susmita Mahapatra

This course discusses CBSE Class 11 Science topic on Waves - Types of Waves, Equation of Plane progressive waves, Energy transmission in waves, Laws of Transverse vibration, Newton's formula for sound in air and Laplace correction, Reflection of Waves, Superposition of Waves and Stationary Waves.

CBSE Class 11 - Waves

State topper in school exams, selected in IIT Kharagpur, M.Sc., 30 yrs in teaching.

Pradeep Kshetrapal

Different concepts and equations of oscillations are explained with help of questions asked in previous NEET examinations.

NEET 4 Oscillations

wave motion and waves on a string, equation of traveling wave, velocity of a wave on a string, interference and the principle of superposition, reflection and transmission of waves, standing wave, laws of transverse vibrations of a string: sonometer, transverse and longitudinal waves, polarization of waves.

(Hindi) Wave Motion In One Direction

Rahul Mandal

This course will help you to understand the Nature of Electromagnetic waves or radiation.  And all the topics which are related to this course are explained in so simple and easiest method with deep understanding i.e. Introduction of EMW,  properties of Electromagnetic waves or radiation, visible spectrum for EMW radiation regions and also some importants Numericals based on this theory.  And guys don't worry those all topics are explained in basic terms.  So if you like my lessons then do RATE, REVIEWS AND RECOMMEND to this course and don't forget to follow me for lettest updates regarding to this course.  Thank you

Lessons

21 lessons • 3h 20m