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Wave Properties. Learning Goals: Define wavelength, frequency, period, and amplitude. Describe the relationship between frequency and wavelength. Explain how a wave’s energy and amplitude are related. Calculate wave speed. Parts of a Wave. Crest: high point of the wave form
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Wave Properties Learning Goals: • Define wavelength, frequency, period, and amplitude. • Describe the relationship between frequency and wavelength. • Explain how a wave’s energy and amplitude are related. • Calculate wave speed.
Parts of a Wave • Crest:high point of the wave form • Trough: low point of the wave form • Compression: more dense region of a longitudinal wave • Rarefaction: less dense region of a longitudinal wave crest Rest position trough
Wave Properties Wavelength: Defined - distance between one point on a wave and the nearest point just like it Distance from… 1) Crest to crest2) Trough to trough3) Start of one compression to the next4) Start of one rarefaction to the next wavelength wavelength wavelength wavelength Rest position
Wave Properties Frequency: • Defined - the number of wavelengths (or number of vibrations) that pass a fixed point each second • Frequency is expressed in hertz (Hz). • A frequency of 1 Hz means that one wavelength (or one vibration) passes by in one second. Two vibrations per second is 2 Hz. • In SI units, 1 Hz is the same as 1/s.
Wave Properties Period: • Defined -the amount of time it takes one wavelength to pass a point, measured in seconds • As the frequency of a wave increases, the period decreases.
Wave Properties Period (continued): • Consider the following: A wave has a frequency of 2 Hz. This means that two wavelengths pass a point in one second. How much time does it take for one wavelength to pass a point? Answer: 1/2 or 0.5 second, so the period of this wave is 0.5 s.
Wave Properties Period (continued): • What about a wave with a frequency of 3 Hz. This means that three wavelengths pass a point in one second. How much time does it take for one wavelength to pass a point? Answer: 1/3 or 0.33 second, so the period of this wave is 0.33 s.
Wave Properties Wavelength and Frequency: • The relationship is inversely proportional: when one increases, the other decreases.
Wave Properties Wave Speed: • Depends on… the medium it is traveling through. Sound waves usually travel faster in liquids and solids than they do in gases. However, light waves travel more slowly in liquids and solids than they do in gases or in empty space. Also, sound waves usually travel faster in material when the temperature of the material is increased.
Wave Properties Wave Speed (continued): • Calculated by multiplying its frequency times its wavelength • speed (in m/s) = frequency (in Hz) x wavelength (in m) v = ƒλ
Wave Properties Amplitude and Energy: • Amplitude is related to the energy transferred by a wave. • The greater the wave’s amplitude, the more energy the wave transfers.
Wave Properties crest amplitude amplitude trough Measuring Amplitude in a Transverse Wave