1. Light as a Wave: Part 1
SNC2D

2. What is a wave?
A wave is a disturbance which carries energy from one location to another.
The material the disturbance travels through is the medium.
The movement of the disturbance is referred to as propagation.

3. Snapshot of a Wave
The dashed line represents the equilibrium position of the particles.

4. Snapshot of a Wave
The positions of maximum displacement are referred to as crests (positive displacement) and troughs (negative).
The maximum displacement is the amplitude.

5. Snapshot of a Wave
The distance between one crest and the next crest (or one trough and the next trough) is the

6. Snapshot of a Wave
The distance between one crest and the next crest (or one trough and the next trough) is the wavelength, represented by

7. Snapshot of a Wave
The distance between one crest and the next crest (or one trough and the next trough) is the wavelength, represented by l.

8. Snapshot of a Wave
The time it takes one complete wavelength to pass a single point is the

9. Snapshot of a Wave
The time it takes one complete wavelength to pass a single point is the period, represented by

10. Snapshot of a Wave
The time it takes one complete wavelength to pass a single point is the period, represented by T.

11. Snapshot of a Wave
The number of complete wavelengths that pass a single point in one second is the frequency, represented by f.

12. Frequency Frequency is measured in units of s-1 or Hertz (Hz).
“I do not think that the wireless waves I have discovered will have any practical application.”

13. Wave Speed
The speed of a wave is therefore:

14. Wave Speed
The speed of a wave is therefore:

15. Wave Speed
The speed of a wave is therefore:

16. Wave Speed The speed of a wave is therefore:
Practice Question: What is the wavelength of a wave with a speed of 344 m/s and a frequency of 256 Hz?

17. Wave Speed
Practice Question: What is the wavelength of a wave with a speed of 344 m/s and a frequency of 256 Hz?

18. Wave Speed
Practice Question: What is the wavelength of a wave with a speed of 344 m/s and a frequency of 256 Hz?

19. Wave Speed
Practice Question: What is the wavelength of a wave with a speed of 344 m/s and a frequency of 256 Hz?

20. Light is an “EM” wave
Light is actually a transverse wave

21. Light is an “EM” wave
Light is actually a transverse wave, but the perpendicular-to-propagation disturbance is not of particles of a medium but of the electric and magnetic (EM) fields

22. The Speed of Light
Because light waves do not need a medium, they can travel through a vacuum (empty space) and do so at the speed of light: c =

23. The Speed of Light
Because light waves do not need a medium, they can travel through a vacuum (empty space) and do so at the speed of light: c = 3.0 x 108 m/s.

24. The Speed(s) of Light
Light will travel slower in denser media (e.g. glass), but the speed in air is still effectively 3.0 x 108 m/s and