Properties of Waves

Ms. T.

4 Basic Properties of Waves

O AmplitudeO WavelengthO FrequencyO Speed

Amplitude

OMaximum distance the particles of the medium carrying the wave move away from the resting place

Amplitude of Transverse Wave

OThe maximum distance the medium moves up or down from the resting place.

OMeasure from resting place to top of crest or to bottom of trough

Amplitude of Transverse Wave

O The amplitude of the wave is related to the energy of the wave.O The greater the energy the greater

the amplitude.

Amplitude = 3 cm

Amplitude = 1 cm

Amplitude of a Longitudinal Wave

O A measure of how compressed or rarefied the medium becomesO Greater amplitude= tighter

compression

Property 2: WavelengthO A wave travels a certain distance

before it repeats.O The distance from crest to crest

or from trough to trough is one wavelength.

WAVELENGTH

2 cm

1 cm

FrequencyO The number of waves that pass a certain

point in a certain amount of time. O Frequency is measured in HERTZ (Hz) per

secondO A wave that passes a point every second

has a frequency of 1Hz. If 2 waves pass a point every second, it has a frequency of 2Hz.

O Go To this animation click below:O http://www.pbslearningmedia.org/asset/lsp

s07_int_frequency/

SpeedO Different waves travel at different speeds.O Speed = the distance a wave travels in a

certain amount of timeO Formula: Speed = Wavelength x Frequency

O Example: If a wave has a wavelength of 2 meters and a frequency of 3 Hz , What is the speed?O S = W x FO S = 2m x 3Hz O S = 6m/s

Formulas for Frequency & Wavelength

O If you know 2 of the values in the speed formula, you can find the third quantity:O Frequency = Speed WavelengthO Wavelength = Speed Frequency

Find Speed Using Formula:

O S = W x FO A wave has a wavelength of 3mm and a

frequency of 4Hz. What is the speed?O S = W x FO S = 3mm x 4 Hz O S = 12mm/s

O A wave has a wavelength of 5cm and a frequency of 2Hz. What is the speed? O S = W x FO S = 5cm x 2 HzO S = 10cm/s

Finding Frequency using FormulaO F = S or F = S ÷ W

W

O A wave has a speed of 6cm/s and a wavelength of 2cm. What is the frequency of the wave?

O F = S/WO F =6/2 (divide)O F= 3 Hz

O A wave as a speed of 10mm/s and a wavelength of 5cm. What is the frequency of the wave?

O F = S/WO F =10/5 (divide)O F= 2 Hz

Finding Wavelength using Formula

O Wavelength = Speed or W = S÷F Frequency

O A Wave has a speed of 12m/s and a Frequency of 2Hz. What is its wavelength? O W= S/FO W = 12/2O W = 6m

O A wave has a speed of 24cm/s and a frequency of 6 Hz. What is its wavelength? O W= S/FO W = 24/6O W = 4m

Summary: What I should know and be able to do.

O What are the 4 properties of waves?O Which wave property is directly related to energy?O Which wave properties are distances?O Which wave properties are relative to time?O What is the formula for speed? Frequency?

Wavelength?O 2 Waves have the same wavelength and

frequency. How do their speeds compare?O Calculate: A wave’s frequency is 2Hz and its

wavelength is 4m. What is the wave’s speed?