Class 11 Physics Ch 15

 Class 11 Physics Waves chapter 15 Notes

The CBSE NCERT Class 11th Physics Notes encompass a broad spectrum of significant topics and concepts, such as Work, Energy, and Power, Thermal Properties of Matter, Rotational Motion, Thermodynamics, Kinetic Theory, Gravitation, and Laws of Motion, among others.

In physics, waves and vibrations are fundamentally significant phenomena. In this nature, oscillations can be found in a wide variety of shapes. We may easily discover examples of vibration in practically any physical system, from the huge oscillations of sea waves to the atomic jiggling. In terms of physics, a wave is an oscillation or a disturbance that moves across space and time while undergoing an energy transfer. When energy is transferred between two points via wave motion, the medium's particles are frequently not permanently moved, hence there is little or no accompanying mass movement. Instead, they consist of vibrations or oscillations near fixed points.

 • Waves Class 11 Physics Chapter 15 Notes

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Read or Download - Class 11 physics chapter 15 Waves Pdf Notes

 The waveform is a form of turbulence which propagates through a physical medium due to the repeated periodic movement of the particles of the medium around their average location with no real reality.
 Material transport.

 • wave characteristics

 The characteristics of the waves are as follows:
 (i) The particles of the medium released by a wave produce relatively weak vibrations around their erratic position, but the particles are not moved permanently in the direction of propagation of the wave.
 (ii) Each successive particle of the medium performs a movement similar to its predecessors along the line of displacement of the wave.
 (iii) Only the energy transfer occurs during the movement of the waves, but not part of the medium.
 There are mainly three types of waves: (a) mechanical or elastic waves, (b) electromagnetic waves and (c) matter waves.

 • Mechanical waves

 Mechanical waves can only be produced or propagated on a physical support.  These waves are controlled by Newton's laws of motion.  For example, waves on the surface of the water, waves on stars, sound waves, etc.

 • Electromagnetic waves

 These are waves which do not require any physical support for their production and propagation, that is to say that they can pass through vacuum and any other physical support.  Common examples of electromagnetics
 The waves seem light;  Ultraviolet light;  RadioWave, microwave, etc.

 • Matter waves

 These waves are associated with particles of moving matter, such as electrons, protons, neutrons, etc.  There are two types of mechanical waves:
 (i) speed of the transverse waves, (ii) speed of the longitudinal waves,
 • movement of transverse waves
 In the transverse waves, the particles of the medium vibrate at right angles in the direction of propagation of the wave.  Waves on wires, surface water waves and electromagnetic waves are transverse waves.  Electromagnetic wave disturbances (which include light waves) are not the result of particle vibrations, but rather of the oscillation of electric and magnetic fields at right angles to the direction in which the wave travels.  .
 • longitudinal wave speed
 In waves of this type, the particles of the medium vibrate around their average position in the direction of energy propagation.  They are also called pressure waves.  Sound waves are longitudinal mechanical waves.
 • wave length
 The distance traveled by turbulence during a vibration by an average particle is called wavelength (λ).  In the case of a transverse wavelength, it can also be defined as the distance between two successive crotches or hollows.  In the case of a longitudinal wave, the wavelength (λ) is equal to the distance from the center of one compression (or refraction) to the other.
 • Wave speed
 Wave speed is the rate of propagation over time of wave speed in a given environment.  It is different from the speed of the particle.  The speed of the wave depends on the nature of the medium.
 Wave speed (vel) = frequency (v) x wavelength (λ)

 • Dimensions

 The amplitude of a wave is the maximum displacement of the particles of the medium from their average position.

 • Frequency
 Frequency is the number of vibrations made by a particle in one second.  It is designated by v.  Its unit is Hz (Hz) v = 1 / T
 • time limit
 The time it takes for a particle to complete a single vibration is called the period of time.
 T = 1 / V, it is expressed in seconds.
 • The speed of the transverse waves in a rod is given by

 Where T is the tension in the rope and μ is the mass per unit length of the rope, μ is also called the linear mass density of the rope.  The SI unit of किलो is kg m - 1.
 • The speed of longitudinal waves in an elastic medium is given by

 Where E is the modulus of elasticity of the medium and ρ is the density of the medium.  In the case of solids, E is the youth elastic modulus (Y), then

 • Newton's formula for the speed of sound in air
 Newton says change occurs when sound waves travel through air or gaseous media
Under STP conditions, the speed of sound in air is calculated based on Newton's formula, which is 280 ms-1.  However, the value determined experimentally is 332 ms-1.
 According to Laplace, during the propagation of sound waves, the change occurs in adiabatic conditions because the gases are thermal insulators and are alternately compressed and refracted at high frequency.

 • Factors affecting sound factors
 The speed of sound in any gaseous medium is influenced by a large number of factors such as density, pressure, temperature, humidity, wind speed, etc.
 (i) The speed of sound in a gas is inversely proportional to the square root of the density of the gas.
 (ii) The speed of sound is independent of the change in gas pressure, provided that the temperature remains constant.
 (iii) The speed of sound in a gas is proportional to the square root of its absolute temperature.
 (iv) The speed of sound in moist air is higher than the speed of sound in dry air.
 (v) If the wind flows at an angle in the direction of sound propagation, the speed of sound is v + w the cos flux, where w is the speed of air.
 • General equation of progressive waves
 "A progressive wave is a wave which moves in a direction with a constant amplitude, that is to say without attenuation."
 As a wave motion, the displacement is a function of space as well as time, so that the displacement relation is expressed as a joint function of position and time:
 y (x, t) = a sin (kx - + t + t)
 We can also choose the cosine function instead of the sine function.  Here A, K, ω and Ф are the four constants for a given wave and are known as the amplitude, the angular wave number, the angular frequency and the initial phase angle of the given wave.
 • Relationship between phase and path difference

 • Wave motion can be reflected from a rigid or free range.  A traveling wave, at a rigid border or at a closed end, is reflected with a phase inversion, but reflection at an open border occurs without any phase change.
 • Principle of superposition of waves
 When several waves meet simultaneously in a medium at a given moment, the algebraic sum of displacement due to each wave at this moment is the algebraic sum of displacement.

 • standing waves or standing waves
 When two sets of traveling wave trains of the same type (ie Longitudinal or transverse) travel with the same speed in the same amplitude and the same time / frequency / wavelength, opposite directions with the  same speed, superimposed waves.  Are formed from a new set of.  These are called standing waves or standing waves.

 • Traveling waves

 1. disruption of progress in neighborhoods;  It is transmitted from particle to particle.  Each particle performs the same type of vibration as the precursor, although at a different time.
 2. Waves come in the form of ridges and trolls, namely sine / cosine functions, which move through rooms with a fixed speed.
 3. Each particle has the same dimension;  Which is obtained in time according to the progression of the wave.
 4. The phase of each particle varies continuously from 0 to 2 particles.
 5. No particle remains permanently at rest.  Twice during each vibration, the particles are relaxed for the moment.  Different particles reach this condition at different times.
 6. All particles have the same maximum speed that they reach one after the other, as in a wave.
 7. There is a regular flow of energy in each plane towards the propagation of the wave.  The average energy in a wave is half potential and half kinetic.

 • Standing waves
 1. The disturbance is constant, there is no forward or backward movement of the wave.  Each particle has its own vibrational characteristics.
 2. The waves have the presence of a sine / cosine function, which shrinks twice in a straight line with each vibration.  It never progresses.
 3. Each particle has a certain allocated dimension.  Some have zero amplitude (knots) while some have maximum amplitude (knots)
Progressive waves
 1. A progression disorder on the wings.  It is delivered from particles to particles.  Each particle performs the same type of vibration as the precursor, but at a different time.
 2. The waves are peaks and trolls, i.e. functions of sine / cosine, which move in wings at a constant speed.
 3. Each particle has the same dimension, which is obtained on time based on the progress of the wave.
 4. The stage of each particle varies continuously from 0 to 2 particles.
 5. The particle does not permanently stay at rest.  Twice during each shaking, the particles are relaxed at the present time.  Different molecules achieve this condition at different times.
 6. All molecules have the same maximum velocity achieved by one after another, as in a wave.
 7. There is a uniform flow of energy in each plane toward the propagation of the wave.  The average energy in the wave is half the voltage and half kinetic.

 • standing waves
 1. Turbulence is constant, there is no movement forward or backward from the wave.  Each particle has its own vibrational properties.
 2. The waves have the function of sine / cosine, which shrinks twice in a straight line in each vibration.  It never progresses.
 3. Each particle has a certain specific dimension.  Some have zero capacity (AIs), and some always have maximum antinodes.  Each particle1eat is given at the same time.
 4. All the particles in the half-wave have a fixed phase and all the particles in the other half of the wave have the same phase together in the opposite direction.
 5. There are molecules, which are permanent in comfort (nodes) and all other particles have their own individual displacement, which they receive simultaneously.  These particles are relaxed twice with each vibration at the same time.
 6. All molecules, combined, achieve their individual assigned velocities based on their location.  Molecules (nodes) in the form of a wave have zero velocities at all times.
 7. There is no energy flow in any plane.  Each particle has its own different energy.  They all achieve their RE values.  At one time and all energy becomes KB.  Next time

 • In the simplest method of vibration, when a fixed wave is created in a chain of length l determined at its ends, the nodes are formed at the fixed end and an antinode is formed at the midpoint.  The base mode frequency of the vibration (or first harmonic) is given by

 • Chain frequency stretched
 In general, if the chain vibrates at the ends of p, then the chain frequency is repeated under this mode

 Based on this relationship, three laws of accidental vibrations of stretched wires arise.  It is the law of height, the law of stress and the law of mass.
 Base length
 The base frequency v is inversely proportional to the length L of the inverse proportional chain.

 The rule of stress
 The original frequency is directly proportional to the square root of the tension in the chain.

 Broad law
 When L and T are constant, the fundamental frequency is inversely proportional to the square root of the length of the per capita share of a given chain.

 • Beats
 The phenomenon of uniform increase and decrease in sound intensity, when two waves of approximately the same frequencies are called traveling along the same line and competing in the same direction, are called pulses.
 The increase in the volume of the sound represents a rhythm and the number of pulses per second is called the pulse frequency.  As follows:
 vb = (v1-v2)
 Where v1 and v2 are the frequencies of the interfering waves; v1 exceeds v2.
 Doppler effect
 According to the Doppler effect, the more there is a relative movement between the sound source and the listener, the apparent frequency of the sound heard by the listener differs from the actual frequency of the sound emitted from the the actual frequency of sound emitted by the source.
For sound the observed frequency v’ is given by

Here v = true frequency of wave emitted by the source, v = speed of sound through the medium, v0 the velocity of observer relative to the medium and vs the velocity of source relative to the medium. In using this formula, velocities in the direction OS (i.e., from observer towards the source) are treated as positive and those opposite to it are taken as negative.

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