1. Waves and Wave Interactions
Chapter
Physical Science

2. Waves
A wave is a disturbance that carries energy through matter or space.
Medium – the environment that the wave travels in (ex: water, air)

3. Waves Transfer Energy
Waves will spread out in all directions carrying energy.
The energy is conserved in the system following both the law of conservation of momentum and energy.

4. Waves transfer Energy EX: Water waves do work on a boat
EX: Sound waves do work on your eardrum
EX: Light waves do work on your eye

5. Energy of Waves

6. Wave Speed
The speed of a wave will depend on the medium it travels through
The state of matter determines the speed of the wave.
EX: In gases the particles are spread out so the wave travels slower in gases
EX: In liquids, the particles are closer together so the energy is transferred quicker between particles of that medium
EX: In solids, the particles are tightly packed together so the wave travels very quickly through solids

7. Parts of a Wave

8. Doppler Effect – Occurs when the wave source is moving.
Image Simulation
Breaking the sound barrier

9. Light Waves Light waves occur in different frequencies and wavelengths
Light waves are represented on the electromagnetic spectrum
The Electromagnetic Spectrum consists of visible light and other waves that cannot be seen.

10. Electromagnetic Spectrum

11. Electromagnetic Spectrum

12. The Electromagnetic Spectrum
Consists of light at all possible energies, frequencies, and wavelengths.
Visible light is only a small part of the spectrum.
The spectrum also contains X-rays, Ultraviolet rays, Radio Waves, Gamma waves.

13. The Nature of Light Light acts as a wave in that it:
produces interference patterns like water waves
Follows the laws of reflection, diffraction, and refraction

14. The Nature of Light Light also acts as a particle
These particles are called PHOTONS
A beam of light is considered to be a stream of photons.
Photons do not have mass…they are like “bundles of energy”

15. Light Wave Speed
All electromagnetic waves in empty space travel at the same speed
The speed of light is: 3.00 x 108 m/s or 186,000 miles/second
Light will travel slower when it has to pass through a medium such as air or water

16. Wave Interference

17. Wave Interference
The combination of two or more waves of the same frequency that result in a single wave
Two types:
Constructive Interference
Destructive Interference

18. Constructive Interference
Occurs when two waves meet and produce a larger wave.

19. Destructive Interference
Occurs when two waves meet and make a smaller wave or cancel each other out.

21. Wave Interference
Interference of Light Waves produce colorful displays
Ex: Soap bubbles often show reds, blues, and yellows on their surface because of the interference of light.

22. Wave Interference Simulation

23. Wave Interactions

24. Wave Interactions
Waves may interact with each other when traveling through a medium
There are 3 possible outcomes:
Reflection, Diffraction, and Refraction

25. 1. Diffraction
A change in the direction of a wave when the wave finds an obstacle or an edge

26. 2. Reflection
The bouncing back of a wave when the wave hits a surface or boundary

27. Reflection of light Every object reflects some light
Rough surfaces reflect light in many directions
Smooth surfaces reflect light in one direction

28. Law of Reflection
When light hits a smooth surface, the angle of incidence equals the angle of reflection.

29. 3. Refraction
The bending of waves when they pass from one medium to another
Causes the wave to bend
Prism Example:

30. Laws of Refraction
When light travels in a medium with a higher speed to a medium where it slows down, the ray is bent toward the normal

31. Laws of Refraction
When light travels from a medium where it is slower to a medium where it can travel faster, light bends away from the normal

32. Refraction
Because of refraction images appear to be in different positions

33. Wave Absorption Energy from the wave is absorbed into the medium
Often as heat (measured as thermal energy).

34. Thermal Energy Thermal conductors have a high rate of energy transfer
Thermal insulators have a slow rate of thermal energy transfer
Rate of thermal energy transfer is dependent on temperature, color, texture and exposed surface area of the object.

35. Thermal Equilibrium
The amount of thermal energy absorbed is equal to the amount of thermal energy emitted.
The temperature remains constant.