1. Essential Question: What are the types and properties of waves?
Unit 9: Waves
Essential Question:
What are the types and properties of waves?
3/25/2013
Mrs. Lisa Simmons

2. What is a wave?
A Wave is an oscillation accompanied by a transfer of energy that travels through space or mass.
A medium is the substance or matter that a wave moves through.

3. What is a wave? 2 Classifications of Waves:
Mechanical Waves: waves that use a medium of transfer their energy. Examples: Sound, water waves
Electromagnetic waves – are waves that transfer their energy with or without a medium. Examples: Radio waves, light waves, microwaves, etc.

4. What is a wave?
Electromagnetic Spectrum

5. A. Types of Waves
1. Longitudinal waves (AKA-Compressional waves) are waves in which the particles in the medium moves parallel to the direction of a wave.
Longitudinal waves are mechanical waves.
Sound waves are longitudinal waves.

6. A. Types of Waves
2. Transverse waves – where the wave energy moves perpendicular to the direction of the wave.
Most transverse waves are electromagnetic, some can be mechanical.
Light waves are transverse waves.

7. A. Types of Waves
3. Surface waves – energy of the wave are transfer through a medium by circular motion.
These waves are neither transverse or longitudinal waves.
Ocean waves and some Earth surface waves move with these types of waves.

8. Properties of Waves Crest – Highest point of a wave.
Trough – lowest point of a wave.
Wavelength (l) – One complete wave or cycle. (one complete crest and trough). Wavelength is measured in meters (m).

9. Properties of Waves In longitudinal waves …
Compressions – are the “crest”.
Rarefactions – are the “trough”.
Wavelength – is one complete of a compression and rarefaction.

10. Properties of Waves
Amplitude (A)– The height of a wave (from midline to crest or trough).
Frequency (f) – # of waves per second (SI unit for this is the Hertz (Hz)).
Period (T) – the time it takes for one complete wave cycle (measured in seconds)

11. V l f Wave Speed V = m/s f = hertz (Hz) or Waves/s l= m
Waves have speed (velocity). It is calculated using the formula:
Wave speed (Velocity) = frequency x wavelength
V = m/s f = hertz (Hz) or Waves/s
l= m V l f

12. Sample Problem:
A wave has a velocity of 25 m/s and a wavelength of 1.5 m. What is the wave’s frequency?

13. Sample Problem #2
A wave has a frequency of 800 Hz and a wavelength of 2 meters. What is the wave’s velocity/speed?