Class 12 Physics Waves motion Notes

Class 12 Physics Waves motion Notes



Unit – 3
Wave and optics
Chapter – 6
Waves motion

 


PDF Link:- View


Also Visit:-

Wave motion

Wave motion is the transfer of energy in the form of disturbance from one place to another place due to the periodic motion of particles. Wave motion can be classified into two types according to medium.

1. Electromagnetic Wave

2. Mechanical Wave

1. Mechanical Wave

The wave which requires a material medium for its propagation is called a mechanical wave. For example:- Round wave, Wave in the string, etc.

2. Electromagnetic Wave

The wave which doesn’t require any material medium for its propagation is called an electromagnetic wave. For example:- Lightwave, radio waves, etc.

On the basis of the direction of vibration particle waves are of two types:

i. Transverse Wave

If the vibration of a medium particle is right angle to the direction of wave propagation, then such wave is called a transverse wave. They are transmitted in the form of crest trough.

Transverse Wave

Longitude wave

If the vibration of a medium particle is in the direction of propagation at a wave, such wave is called a longitudinal wave. In longitudinal waves, particles are vibrates in the form of compression and rarefaction. Example sound wave

Wave motion

Some terms related to wave motion

Wave motion

Displacement

A distance of vibrating particles from a mean position is called Displacement.
It is denoted by y

Amplitude

The maximum displacement of a vibrating particle from its mean position is called Amplitude. It is denoted by a

Wavelength

The distance between any two successive Maximum or minimum is called wavelength
Or

The distance traveled by a wave in one complete cycle is called wavelength. It is denoted by λ.

Frequency

The number of complete oscillations made by a wave in one second is called frequency. It is denoted by ‘F’ and given by,

Class 12 Physics Wave Motions Notes

Time period

Time taken by vibrating particles to complete one vibration is called the time period. It is denoted by ‘T’ and given by,

Class 12 Physics Wave Motions Notes

Phase or phase angle

The state of vibrating particles at a given time is called phase. It is expressed in terms of angle.

Figure

For distance λ, phase 2π

Class 12 Physics Wave Motions Notes

Progressive wave

The wave which is traveling in a forward direction with constant amplitude and frequency is called a progressive wave.

Progressive wave

Fig: Progressive wave

Suppose a wave travels in a direction from left to right with velocity ‘v’ in which all particles vibrate with sample harmonic motion. The displacement of the vibrating particle from the origin(o) is given by,

y = asinωt—(i) ( where ‘a’ is amplitude and ‘ω’ its angular velocity

Also, suppose another vibrating particle is at point ‘p’ which is at distance ‘x’ from the origin as shown in the figure. Let φ be the phase angle of the particle at point ‘p’ given by

y = asin(ωt-φ)—(ii)

we know that

for distance λ, the phase angle is 2𝝅

For distance ‘x’, the phase angle is 2𝝅/λ.x

wave motion

equation (iii) is the required equation for a progressive wave traveling from left to right

If the progressive wave is traveling from right to left then its equation is

y = asin 2π / λ (vt+x)

Equation of progressive also written as,

y = asin (wt – kx)
where, k = 2π / λ

is called wave number of propagation constant.

Super Position therom

When a number of waves having displacement y1 – y2 – y3 – yn, Propagates in a medium then the resultant displacement of a wave at any instant is equal to the vector sum of displacement due to. individual wave. This phenomenon is called the superposition theorem. If y be the resultant displacement then,

Stationary/standing wave

When two progressive waves of the same Amplitude and frequency travel with the same speed in a medium in opposite direction they will super each other and a stationary wave is formed

Fig: Stationary wave

Fig: Stationary wave

Let us consider two waves of the same amplitude ‘a’ same frequency ‘f’ having ‘λ’ traveling in opposite directions with their displacement

wave motion

Applying superposition theorem

Class 12 Physics Wave Motions Notes

where [A = 2coskx is the amplitude of stationary wave]

∴equation (iii) is the equation of stationary wave.

Condition of nodes and antinodes

1. For nodes

For node, the amplitude is zero

i.e. A = 0

or, cos kx = 0

Class 12 Physics Wave Motions Notes

2. For antinodes

wave motion

At x = 0, λ/2,λ, 3λ/2 —– antinodes are formed


If you want to ask anything, please contact us by Messaging us on Social Media. 

 Social Media links:-


Tags

Class 12 Physics Notes All Chapters (New Curriculum)

Class 12 Physics Notes 2078: Complete Physics Guide (New Syllabus) | Questions Answers and Guide | Class 12 Physics Book Solution Guide  | Class 12 Physics Book PDF 2078 Solution | Class 12 Physics Book Notes 2078 Guide | Class 12 Physics All Chapter Notes | Physics Chapter Wise Notes. Class 12 Physics Waves motion Notes

2 Comments

  1. Sudip Dhamala

    Thanks sir for all sub pdf and YouTube channel in all sub Nate available for science thanks you so much 💞

Leave a Reply

Your email address will not be published. Required fields are marked *