1. (Based on medium) 2. Mechanical Waves
A material medium is necessary for the transmission for mechanical waves. Mechanical waves cannot travel through vacuum.
Due to forces on particles in the “medium” that are next to each other, the disturbance is transmitted from one layer to the next through the medium.

2. 3. Non Mechanical Waves (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.

4. II. 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.

5. Each term will be explained….
A. Parts 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….

6. 1. longitudinal
Amplitude of a longitudinal wave is a measure of how stretched or compressed

7. 2. transverse

8. 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

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

10. 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 ?
= 0.6 m,
v = 3.0 m/s
f = ?
By using the wave
equation, v = ƒ ƒ = v/ 
f = (3.0 m/s)/(0.6 m) ƒ = 5.0 Hz
The unit of ‘m’ cancel out—and you are left with 5.0/s which is 5.0 Hz
Then the period of this wave is ???
Period T = 1/ƒ T = 1/5.0 or 0.2 s