Wave:  disturbance in a medium

Periodic waves:  repeat in a regular pattern

Pulse wave:  single disturbance in a medium

 

Wave speed = (wavelength) x frequency   v=lf

SI units:  v = m/s        l=m        f=Hz= (1/s)  T= period = (s)

 

Sound travels at 340 m/s in air

Light travels at 3.0 x 10⁸ m/s

 

FM radio waves broadcast at 1 kHz = 1.0 x 10³ Hz

AM radio waves broadcast at 1 MHz= 1.0 x 10⁶ Hz

 

Doppler effect:  A change in the apparent frequency of sound due to the motion of the source or the receiver.  You probably associate the Doppler effect as the change in pitch (frequency) of a loud car just as it passes you.  The pitch drops as the object moves by the observer.  The Doppler effect is used in weather forecasting and astronomy.