Waves and the Doppler Effect

Parts of a Wave

Wave PropertiesWavelength

Wavelength,Wavelength,, is the distance between two , is the distance between two consecutive peaks.consecutive peaks.

Wave PropertiesAmplitude

Amplitude is the height of the wave above Amplitude is the height of the wave above or or below the equilibrium point.below the equilibrium point.

Wave PropertiesFrequency

Frequency, f, is the number of waves passing a particular Frequency, f, is the number of waves passing a particular point in one second.point in one second. Also known as pitch.Also known as pitch.

Examples of Frequency

What is the frequency of the second hand of What is the frequency of the second hand of a clock?a clock?

Frequency = 1cycle/60 secFrequency = 1cycle/60 sec

What is the frequency of US Presidential What is the frequency of US Presidential elections?elections?

Frequency = 1 election/4 yrsFrequency = 1 election/4 yrs

8. DOPPLER EFFECT

Refers to the change in frequency when there is relative motion between an observer of waves and the source of the waves

Doppler with SoundDoppler with Sound

Doppler with Water

The Doppler effect-Change in frequency due to the source or receiver greater Change in frequency due to the source or receiver greater

the speed the source, greater the Doppler effectthe speed the source, greater the Doppler effect Stationary bug Stationary bug

Bug swimmingBug swimming

Blue Shift-increase in frequency Blue Shift-increase in frequency Red Shift- Decrease in frequencyRed Shift- Decrease in frequency

Supersonic

Bow waves

V-shaped pattern made by overlapping crestV-shaped pattern made by overlapping crest

Shock Waves Produced by supersonic aircraft, Produced by supersonic aircraft,

three-dimensional cone shapedthree-dimensional cone shaped Sonic boom – sharp crack heard Sonic boom – sharp crack heard

when conical shell of when conical shell of compressed air that sweeps compressed air that sweeps behind a supersonic aircraft behind a supersonic aircraft reaches listeners on the ground reaches listeners on the ground below.below.