1. Characteristics of Waves SI

2. What is a wave? A disturbance through a medium as energy is transmitted through that medium Energy is the ability to do work, therefore: Sound waves do work on your eardrum Light waves do work on your eye The bigger the wave, the more energy it carries

3. Types of Waves: Mechanical Mechanical waves – waves that require a medium Mechanical waves travel fastest through solids because the particles of a solid are more tightly packed together

4. Types of waves: Electromagnetic Electromagnetic waves – waves that do not need a medium to travel Examples: Visible light Radio Microwave Infrared (IR) Ultraviolet (UV) light X ray Gamma Ray

5. Shape of Waves: Transverse Transverse waves – simple sine curve The motion of the particles in the medium is perpendicular to the motion of the wave Light waves are transverse waves Amplitude - The greatest distance that particles are displaced from their original resting positions or half the distance between the crest and the trough Crests – highest points Troughs – lowest points Larger waves have larger amplitudes and carry more energy Louder sounds have larger amplitudes

6. Shape of Waves: Transverse

7. Shape of Waves: Longitudinal Longitudinal waves -have compressions and rarefactions The motion of the particles is parallel to the direction that the wave travels Sound waves are longitudinal waves Compressions – crowded areas, medium becomes more dense Rarefactions – stretched out areas, medium becomes less dense

8. Shape of Waves: Longitudinal

9. Surface Waves Move circular (combination of perpendicular and parallel motions)

10. More Wave Properties Wavelength ( ) - The distance between two identical parts of a wave Period - The time required for 1 full wavelength of a wave to pass a certain point Represented by “T” (units = seconds) THINK – PERIOD OF TIME!!!!!!!! Frequency - The number of cycles/wavelengths per unit of time Represented by “f” (units = Hertz (Hz)) Frequency = 1/T

11. Frequency, Wavelength, and Energy What happens to the wavelength as frequency increases? What variables affect the color of light that you see? Higher frequency = more energy and shorter wavelength…The more wavelengths per unit time, the more energy.

12. Wave Speed Speed = wavelength / period, so… Wave speed = frequency x wavelength Wave speed depends on medium They travel the fastest in solids than in air or water Why? In a gas, particles are farther apart so it takes longer for them to bump into each other In liquids, particles are closer together so waves travel faster In solids, particles are very close together so waves travel the fastest

13. Doppler Effect Pitch is determined by frequency Sound waves travel out from an object in wave fronts and hit your eardrum Ambulance example: When the ambulance moves toward you, the sound waves are compressed – so the waves hit your eardrum at a higher frequency – higher pitch When the ambulance moves away from you, the sound waves are stretched out, so the frequency is lower – pitch is lower Doppler effect can also happen in light and other types of waves