# Textbook pages 92-99.  A disturbance that travels through a medium.

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Textbook pages 92-99

 A disturbance that travels through a medium

 Medium: a substance that carries the disturbance from one location to another

 A disturbance that travels through a medium  Medium: a substance that carries the disturbance from one location to another ▪ How? The particles of the medium interact with particles next to them allowing the disturbance to travel Examples of a medium  Water  Air  Ground

 Transports energy from one place to another

 Particles of the medium are only temporarily displaced from the rest position

 Transports energy from one place to another  Particles of the medium are only temporarily displaced from the rest position ▪ Does not transport matter

 Propagation  Amplitude  Wavelength  Frequency

 Waves are distinguished by the way they propagate through a medium

 Transverse Waves  Propagates perpendicular to the motion of the medium

 Transverse Waves Equilibrium

 Longitudinal Waves  Propagates parallel to the motion of the medium

 Longitudinal Waves  Propagates parallel to the motion of the medium

 Longitudinal Waves  Propagates parallel to the motion of the medium

 Longitudinal Waves  Propagates parallel to the motion of the medium

 Related to the amount of energy transferred by a wave

 Transverse Waves  Maximum distance travelled by a particle in the medium compared to its equilibrium position Equilibrium

 Transverse Waves  Depends on energy transmitted by the wave ENERGYAMPLITUDE

 Longitudinal Waves  How tightly the medium is pushed together at the compressions

 Longitudinal Waves  Depends on the density of compression DENSITYAMPLITUDE

 Length of a wave’s complete cycle  Transverse Waves

 Length of a wave’s complete cycle  Longitudinal Waves

 Number of cycles per unit of time  Measured in Hertz (Hz) – the number of cycles per second  1 Hz = completes one full cycle in one second

 Speed of a wave depends on  Medium it travels in  Temperature

 Speed = frequency x wavelength

 v = f x  v = speed (m/s)  f = frequency (Hz)  = wavelength (m)

 What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz?

f = 170.5Hz = 2.00m

 What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? f = 170.5Hz = 2.00m v = ?

 What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? f = 170.5Hz = 2.00m v = ? v = f x

 What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? v = (170.5Hz)(2.00m) v = 341 m/s f = 170.5Hz = 2.00m v = ? v = f x

 What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? v = (170.5Hz)(2.00m) v = 341 m/s f = 170.5Hz = 2.00m v = ? v = f x The speed of the sound wave is 341 m/s

 Mechanical Waves  Electromagnetic Waves

 Can only propagate in a medium

 How? A disturbance changes the physical shape of the medium and passed onto neighbouring particles

 Can only propagate in a medium  How? A disturbance changes the physical shape of the medium and passed onto neighbouring particles  Examples: water waves, sound waves, seismic waves

 Can propagate in a medium and a vacuum

 Can propagate in a medium and a vacuum  Carry Radiant Energy  Examples: light waves in space

 Categories of electromagnetic waves  Classified by frequency and wavelength FREQUENCYENERGY

Long Low Short High

 Radio Waves  Smallest frequency  Invisible & transport little energy  Example: Radio, Television, Microwaves, Cellphones

 Infrared  Invisible, but feel the warmth emitted  Example: Night vision goggles, short-distance communication (wireless keyboards, remote controls, etc.)

 Visible Light  Only electromagnetic waves that can be seen by humans  Together, colours make up white light  Example: Photography, movies, computer screens

 Ultraviolet Rays (UV)  Invisible to humans  Greater frequency, transport more energy  Responsible for suntans, but can cause cancer  Example: sterilization of surgical instruments, treatments

 X-Rays  High frequency  Able to travel through media opaque in visible light  Example: baggage inspection, radiography

 Gamma Rays  Highest frequency and transports the highest energy  Travel easily through matter  Can cause burns, cancer, and genetic mutations  Example: cancer treatment, food preservation

 Read Textbook pages 92-99  Do Workbook pages 49-52

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