1. Chapter 14 - Waves A wave is a rhythmic disturbance that carries energy through matter Waves need a material (medium) to travel through. This is why sound doesn’t travel through a vacuum Wave Pulse – a single disturbance Continuous Wave – continuous disturbance

2. Transverse – a wave that moves perpendicular to the direction of movement. Ex: light Longitudinal – a wave that moves parallel to the direction of the wave. Ex: sound 2 Types of Waves

3. Anatomy of a Wave Wavelength (λ) – distance between two similar points Wave Height – from top to bottom of a wave Crest – top of the wave Trough – bottom of the wave Amplitude (A) – distance from equilibrium

4. Waves at Boundaries The waves that strikes a boundary is called an incident waves. When a wave strikes a boundary some energy is transmitted and some is reflected backward (reflected wave). Whether the reflected wave is upright (erect) or downward (inverted) depends on the density of the two mediums

5. Interference Superposition - when two waves meet at the same place at the same time. Destructive interference – superposition with opposite amplitudes Constructive interference – superposition with same amplitudes. The result is a wave with larger amplitude.

6. Up To Now Waves need a material (medium) to travel 2 Types of Waves – Transverse and Longitudinal Wavelength (λ) – distance between two similar points Amplitude (A) – distance from equilibrium Waves at boundaries –Rigid – almost all the energy is reflected back and inverted –Less Rigid – some energy is reflected back on the same side, some is transmitted through The velocity only depends on the medium Interference

7. Some Details The speed of a wave (velocity) = change in distance/change in time The velocity only depends on the medium (ex. Light slows down in a prism) The greater the amplitude the more energy the wave has. Depends on how the wave is made not its speed. Energy = amplitude 2 Period (T) = time it takes the wave to return to the same point (pendulum) Frequency (f) = number of oscillations (periods) a wave makes each second. Measured in Hertz (Hz) f=1/T (inverse relationship) Both the period and the frequency depend on the waves source not the medium or the waves speed.

8. V=λf Velocity = (Wavelength)(Frequency) How are things related? If λ decreases, f increases, v is the same, a is the same If λ increases, f deceases, v is the same, a is the same

9. Standing Waves A wave appears to stand still when the period of the rope’s vibration equals the time needed for the wave to make one round. Node – the point that doesn’t move when two pulses meet. Created by destructive interference Antinode- the largest amplitude. Created by constructive interference. The 2 pulses will pass through each other without changing shape or size.

10. Law of Reflection the angle of incidence is equal to the angle of reflection

11. Refraction the change in direction of waves at the boundary between two different medium.