1. Waves Unit 1: Lessons 1-2

2. What are waves? A wave is a disturbance that transfers energy from one place to another A medium is the material through which a wave travels

3. How do waves transfer energy? Some waves require a medium in which to travel –Example: sound Some waves do not require a medium in which to travel –example: light, electromagnetic energy

4. How do waves transfer energy? A wave transfers energy in the direction it travels –However the disturbance may not be in the same direction as the wave –Waves are classified based on disturbance in 2 ways: 1.Longitudinal waves 2.Transverse waves

5. What is a longitudinal wave? A longitudinal wave is a wave that contains compressions and rarefactions Particles in the wave travel back and forth in the same direction as the wave (parallel) Example: sound waves

6. What is a transverse wave? A transverse wave is a move that moves up and down creating crests and troughs The particles in the wave move perpendicular to the direction of the wave Example: light waves

7. What are some types of waves? Waves can also be classified by what is disturbed 1.Mechanical waves 2.Electromagnetic waves

8. What are mechanical waves? A wave that requires a medium in which to travel is called a mechanical wave –Sound, water, earthquake waves –Waves can travel through more than one medium (solid, liquid, gas) –Type of medium can effect the speed of a wave

9. What are electromagnetic waves? A wave that can travel without a medium is called an electromagnetic wave –Visible light, x-rays, gamma rays, microwaves, infrared, and radio waves –In space (no medium) all electromagnetic waves travel the same speed Speed of light = 300,000m/s

10. Electromagnetic Spectrum

11. How can we describe waves? A wave can be described in three ways: –Speed of the wave Frequency –Size of the wave Amplitude Wavelength

12. Characteristics of Wave

13. What is amplitude? The wave’s amplitude is a measure of how far the particles in a medium move away from their resting position Greater disturbance = greater amplitude

14. What is wavelength? Wavelength ( ʎ ) is the distance from any point of a wave to an identical point on the next wave Wavelengths are measured crest to crest or trough to trough Shorter wavelength = higher frequency

15. What is frequency? Frequency (ƒ) describes how many waves pass a given point in a single second Wave period (P) is the time required for one second ƒ = 1/P

16. What determines the speed of the wave? Speed of the wave is effected by: 1.medium in which it travels 2.Frequency and wavelength

17. How does the medium effect wave speed? Particles in the wave interact in different ways with the medium –Waves tend to travel faster in solids than liquids and gases Particles closer together which means more interactions or collisions

18. How does the medium effect wave speed? Waves travel slower through denser mediums –Higher density = higher resistance to movement Waves travel faster through higher temperatures –Higher temperatures = higher collisions

19. How does frequency and wavelength effect wave speed? Frequency and wavelength are inversely related –Longer wavelength = lower frequency Higher frequency = faster the wave –Velocity of wave = frequency x wavelength