Monday 10/13 Warm Up Copy the transverse wave below and label the parts (1-4) Agenda 1.Warm Up 2. Waves – Part II Notes 3.Twig – Reflection and Refraction, Prism 1.Wavelength 2.Amplitude 3.Crest 4.Trough Wave type: Light

Waves – Part II Wave Interactions: -Reflection -Refraction -Diffraction -Interference -Standing Waves 110% Effort - From Bell to Bell

Reflection When a wave hits a surface that it cannot pass through and bounces off surface Ex. Ball that bounces off floor in gym Sound wave bouncing off canyon wall 110% Effort - From Bell to Bell

Law of Reflection Law of Reflection states that the angle of reflection equals the angle of incidence -All waves obey this law (sound and light) 110% Effort - From Bell to Bell

Refraction The bending of waves due to a change in speed between mediums When a wave moves from one medium to another medium at an angle, it changes speed as it enters the second medium, which causes it to bend Note - all waves change speed when entering new medium – however not all waves will not bend 110% Effort - From Bell to Bell

Diffraction The bending of waves around the edge of a barrier -When a wave passes a barrier or moves through a hole in a barrier, it will spread out Ex. When a light enters a prism it will bend light into separate wavelengths 110% Effort - From Bell to Bell

Interference When two or more waves meet, they effect each other which is known as an interference Two types of interference: -Constructive -Destructive 110% Effort - From Bell to Bell

Constructive Interference When two waves combine to make a wave with a larger amplitude Think – construct – “build larger” 110% Effort - From Bell to Bell

Destructive Interference When two waves combine to make a wave with a smaller amplitude Think – destructive – “to flatten” 110% Effort - From Bell to Bell

Sound Waves Remember, sound is a longitudinal wave It needs to move through a medium (ex. door, wall, water, air) SONAR – use to locate objects underwater

Speed of Sound The speed of sound at room temperature (20 c) is 342 m/s However, it depends on the: Elasticity Density Temperature Of the material

Elasticity, Density and Temperature Elasticity – the ability of a solid to return to its original shape after being deformed Sound moves best in solids that are elastic compared to liquids or gas

Density and Temperature Density – the amount of matter in a given space Sound moves slower in denser materials Pb, Ag > Fe, Steel More Dense > Less Dense

Temperature Temperature – the measurement of the average kinetic energy of a substance Higher air temperatures allow sound to move through air faster Air Temperature CSpeed (m/s)

Properties of Sound Pitch – how high or low the sound appears to a person High pitch – high frequency Low pitch – low frequency

Doppler Effect When a moving source appears to have a higher frequency and wavelength when near observer, but a longer wavelength and lower frequency when it moves away Ex. Ambulance sirens

Doppler Effect