Intro to waves

The source of all waves is something that vibrates Wave Description

Wave = a vibration carried through space and time. The high points on a wave are called crests. The low points on a wave are called troughs. The term amplitude refers to the distance from the midpoint to the crest (or trough) of the wave. The amplitude is the maximum displacement from equilibrium Wave Description

12.3 the two types of waves Longitudinal Transverse

Sec Sound travels in Longitudinal waves. High pitch from a tiny bell has a high vibration frequency. Low pitch from a large bell has a low vibration frequency. A young human ear can normally hear pitches from sound in a range from about 20 to 20,000 Hz. –Infrasonic waves are frequencies below 20Hz –Ultrasonic waves are frequencies above 20,000Hz.

Sec Speed of Sound Depends on wind condition Temperature, the warmer the faster Humidity, the more humidity the faster Speed of sound does not depend on loudness or frequency. Sound travels at 340 m/s at room temperature. In water it is 4 times faster, and in steel it is about 15 times faster.

Reflection and Refraction Ch. 12 page 242

12.5 Reflection of sound Reflection = echo Rigid and smooth surfaces reflect sound better. Reverberations are multiple reflections. The angle of incidence is equal to the angle of reflection. (This is the same as with light waves)

12.6 Refraction

Video – refraction of sound Sound waves bend when parts of the waves travel at different speeds. The bending of sound is called refraction. Changes in the medium and/or temperature causes the bending or refraction of sound. Facts: submarines hide in blind spots Ultrasound imaging Bats & dolphins