Chapter 6

• transverse waves are when the particles move up-down or side-to-side
• longitude waves are when the oscillations move backward or forward
• the to-and-fro movements of coils is called oscillations
• sections of longitude waves are compressions and rarefractions
• speed is m/s
• frequency is the number of waves passing any point per second (Hertz / Hz)
• wavelength is the distance between any point on a wave
• amplitude is the loudness or the maximum distance a point moves from its rest positions
• speed = frequency x wavelength
• wavelength letter is lambda
• theres three types of wave effects; reflection, refraction, diffraction
• reflection is when waves hit against a hard surface and reflect back
• refraction is when the speed of waves change as they pass through a different medium and change direction
• diffraction is when waves go through a narrow gap and then spread out
• sound waves are longitude waves
• sound waves are caused by vibrations
• sound waves need a medium to pass through
• sound waves travel through solids, liquids, and gases
• sound waves can be reflected, refracted, and diffracted
• oscilloscope is used to display sound
• mircophone is used to record sound
• the wave shape formed on oscilloscope is called waveform
• sounds that reflect against hard surfaces are called echoes
• Echoes absorb the energy in sound waves
• speed of sound depends on temperature
• sound travels through hot air faster than in cold air
• speed of sound doesnt depend on pressure
• speed of sound is different through variant mediums
• sound travels fastest in solids, fast in liquids, and least fast through gases
• the time that it takes for an echo to reflect back is called echo time
• speed of sound = distance travelled/time taken
• echo = 2 x distance travelled/echo time
• if speed of sound is measured then echo can be measured more accurately
• echo sounder: measures the depth of water underneath a boat using sound waves. longer the time, deeper the water.
• radar: detects position of aircrafts and chips by measuring echo time
• parking sensors: sends warning bleeps when vehicle is too close to an obstacle
• unit for frequency is Hertz (Hz)
• high frequency is also known as high notes (high pitch)
• low frequency is also known as low notes (low pitch)
• human hearing range is 20 Hz to 20k Hz