General Wave Properties

GENERAL WAVE PROPERTIES SECONDARY 3 PHYSICS

Waves Around Us

Water waves

Sound waves

Earthquake (seismic waves)

Note:

Waves carry energy (eg. Electromagnetic waves)

What is a wave?

A wave may be thought of as a spread of disturbance.

Eg: the surface of a pond is actually calm until we drop a pebble. Then the surface of the water starts to move as it is disturbed. That disturbance spreads outwards.

http:// webphysics.davidson.edu/Applets/Ripple/Ripple.html

Types Of Waves

There are two types of waves:

Transverse waves

Longitudinal waves

Transverse Waves

The direction of vibration is perpendicular to the direction of wave travel.

Example of transverse waves:

water waves, electromagnetic waves

http://www. phy . ntnu . edu . tw /java/wave/wave.html

Longitudinal Waves

The direction of vibration is parallel to the direction of wave travel.

Example of longitudinal wave:

sound

http://www.explorescience.com/activities/Activity_page.cfm?ActivityID =50

Parts of a Wave amplitude trough Peak / crest One wavelength

Distance travelled by the wave in 1 second. Unit: ms -1 Wave speed Time taken to produce 1 complete wave Period Number of complete waves produced in 1 second Frequency Shortest distance between two points in phase Wavelength Two points that are moving in the same direction at the same speed and having the same displacement from rest Phase Maximum displacement from rest position Amplitude The high points / low points in a wave Crests / trough Meaning Terms

Metres per second (m/s) Wave speed Seconds (s) Period Hertz (Hz) Frequency Metres (m) Wavelength M etres (m) Amplitude Units Terms

Wave Equation v = f  Speed of wave [ms -1 ] Frequency [Hz] Wavelength [m]

Example: The speed of sound is 330 ms -1 . If the wavelength of the sound was 4m, what was the frequency of the sound? Solution: v = f  330 = f (4) f = 330/4 = 82.5 Hz

Relationship between T and f Period [s] Frequency [Hz]

What is “in phase”