1. Wave Motion & EM Waves (I)
Chih-Chieh Kang
Electrooptical Eng.Dept. STUT

2. What is light?
Light is an electromagnetic wave consisting of an oscillating electric and magnetic field.
Light exhibits wave phenomena, such as interference and diffraction etc.. …

3. What are waves?

4. What Are Waves?
Physically, a wave is a vibrational disturbance from a normal or equilibrium condition that propagates through a medium or space.
Example：sound waves, light waves, radio waves, microwaves, water waves, sine waves, cosine waves, Mexican waves, traffic waves, earthquake waves, waves on a string, and slinky waves.
Mathematically, Waves are solutions to the wave equation：
1-D waves
(z, t)：wave function, v：phase velocity

5. Physical Interpretation of Waves
Wave propagation describes the spreading of a disturbance
Waves transfer energy, momentum from one point to another without the transport of matter
Medium：a substance which carries a wave (disturbance) from one location to another
Example：water, air, solid materials

6. Type of Waves Mechanical waves：These need a medium to propagate in
Example：sound waves
Electromagnetic waves ： These wave do not need a medium to propagate
Example：light waves
Matter wave：Particles such as protons and electrons can be treated as waves

7. Classification of Waves
By orientation - longitudinal wave or transverse wave
By appearance - traveling wave or standing wave
By dimension - Dimensionality (1D, 2D, 3D)
By duration - periodic wave or pulse wave

8. Classification of Waves
Longitudinal wave : distrbance is parallel to the direction of travel －slinky waves
transverse wave:Disturbance is perpendicular to the direction of travel － waves on a string

9. Longitudinal waves & Transverse Waves
(Hecht)

10. Classification of Waves
Traveling waves : A wave that propagates in a transmission medium
Standing waves : A stationary pattern of wave is formed by the superposition of two waves of the same frequency propagating in
opposite
directions
(Serway)

11. Classification of waves
One-dimensional waves (1-D)
Two-dimensional waves (2-D)
Three-dimensional waves (3-D)

12. Classification of Waves
Pulse waves：Disturbance is momentary and suddenly
Periodic waves：Disturbance repeats at regular intervals
(Serway)

13. Characteristic of Waves
crest：the highest point of the wave that is elevated above the equilibrium condition
trough：the lowest point of the wave that is depressed below the equilibrium condition

14. References E. Hecht, Optics, Addison-Wesley.
R. A. Serway, Physics for Scientists and Engineers with Modern Physics, Saunders.
J. D. Cutnell, and K. W. Johnson, Physics, Wiley.