1. Auto slide change for this page, WAIT…..
Introduction to Waves
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2. Table of Contents
Part A : Definition Definition of waves Basic Properties of waves.
Part B : Types of Waves and Terminology Mechanical waves : Transverse and Longitudinal waves Electromagnetic waves Terminology of waves.
Part C : The Wave Equation.
Part D : Common Characteristic of Waves.
Part E : Revision
The basics

3. PART A Definition of wave
A periodic disturbance which travels through a medium from one point in space to the others.
Wave motion means the propagation of waves through a medium.
Wave motion appears in almost every branch of Physics.

4. Basic properties of waves :
Energy is transferred from one place to another in a wave motion.
Motion of the medium (particles of the medium) is usually periodically vibratory.
Only the shape or form of wave travels, not the medium.
Remember to take notes

5. PART B TYPES OF WAVES Waves are classified into different types according to their natures :

6. 1. Mechanical Waves
A material medium is necessary for the transmission for mechanical waves. Mechanical waves cannot travel through vacuum.
Due to elastic forces on adjacent layers of medium, disturbance is transmitted from one layer to the next through the medium.
Water waves, sound, vibration of spring, etc.
Click for
examples
And ...
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according to the direction of vibration, waves are also classified into :
(a) Transverse wave;
(b) Longitudinal waves.

7. 1.1 Transverse Waves
The waveform appears in the shape of sine curve.
A wave in which the motions of the matter particles are perpendicular to the direction of propagation of the wave itself.
Examples
Water waves, pulse in a stretched string,transverse wave demonstrator.

8. 1.2 Longitudinal Waves
A wave in which the motions of the matter particles are in the same direction as the wave propagation.
Sound, or a spring oscillating up and down, etc.Show magnetic longitudinal demonstrator
Examples

9. 2. Electromagnetic Waves
Material medium is not essential for propagation. e/m waves travel through vacuum.
Disturbance of electric and magnetic fields travelling through space.
All electromagnetic waves are transverse waves.
examples
X-rays, radio waves, micro-waves,etc.

10. Each term will be explained….
Terminology of a Wave
A wave is usually described by the following terms :
Amplitude
Wavelength ()
Frequency (f)
Period (T)
Wave velocity (v)
Each term will be explained….

11. The amplitude is the maximum displacement of the medium from its equilibrium position.
The wavelength () is the minimum distance between two points which are in phase.
The frequency (ƒ) is the number of complete oscillations made in one second Unit : Hz
The period (T) is the time taken for one complete oscillation. It is related to frequency by T = 1/ƒ Unit : s
Table of Contents

12. The Wave Equation PART C v = ƒ
The wave velocity is the displacement traveled by the wave in one second ……....
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The wave velocity (v) is related to frequency and wavelength by --
The Wave Equation
v = ƒ

13. Using the Wave Equation Example :
A travelling wave of wavelength 0.6m moves at a speed of 3.0 m/s. What is the period of this wave ?
Now you know  = 0.6 m, v = 3.0 m/s Can you find the frequency of this wave……
By using the wave
equation, v = ƒ = ƒ(0.6) i.e ƒ = 5.0 Hz
Click to see the answer
Then the period of this wave is ???
Period T = 1/ƒ T = 1/5.0 or 0.2 s
Table of
Contents

14. Common Characteristics of Waves
PART D
Common Characteristics of Waves
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Transmission of energy
Reflection
Refraction
Diffraction
Interference
Wave
Wave

15. Let’s take water waves as an example to study the characteristics of waves….
The behavior of water waves demonstrates all these characteristics……..
characteristics
Water Waves

16. Reflection of Waves Reflection of Waves
A travelling wave is reflected when it hits a barrier.
This phenomenon can easily be observed when a travelling water wave hits a reflector in the ripple tank.
Reflector
Reflected
waves

17. Refraction of Waves
- The speed of a water wave increases with depth. This change in speed is accompanied by refraction.
This effect is a consequence of the wave equation, v = ƒ.
Since ƒ is constant, a decrease in v produces a decrease in .

18. Diffraction of Waves
When a travelling water wave hits an obstacle, the wavefronts spreads out round the edge and becomes curved. This phenomenon refers to diffraction.
The wavelength of the wave is not changed in diffraction.

19. Interference of Waves = +
When two or more waves propagating in the same medium meet at the same point, interference is said to occur.
A stable interference pattern can be observed when two water waves of same frequency meet one another in a ripple tank. =
Click for example +

20. Effects of Interference