Introduction to Waves

• Science class is taught by Tr. Lyzz

Introduction to Waves

• The notes explore the types of waves and their properties

Think About It

• Earthquakes are a natural phenomenon
• It may be possible to predict them

Waves

• Waves are disturbances that carry energy from one place to another
• Mechanical waves require a medium (particles) to travel through
• Sound and water waves are types of mechanical waves
• Electromagnetic waves do not require a medium to travel through
• Electromagnetic waves can travel through a vacuum
• Visible light, radio waves, and gamma rays are example of electromagnetic waves

Parts of a Wave

• The crest is known as the peak and is the highest point of a wave
• The rest or equilibrium position is the undisturbed position of the particles if they do not vibrate
• The trough is the lowest point of a wave

Amplitude

• Amplitude is the maximum disturbance from the crest of a wave, measured from its rest position: the height of a wave
• The unit for amplitude (A) is meters (m)

Wavelength

• Wavelength is the set distance that represents the full cycle of a wave
• Wavelength can be measured from crest to crest, trough to trough, or any two consecutive points in the wave cycle
• The unit for wavelength (λ, Greek letter lambda) is meters (m)

Frequency

• Frequency is the number of waves passing a specific point per second
• The unit of frequency is hertz (Hz), which equals 1 cycle per second (1/s)

Learning Check

• Wave A has the same amplitude as wave B
• Wave A has a longer wavelength
• Wave A has a lower frequency
• Wave B has the same amplitude as wave A
• Wave B has a shorter wavelength
• Wave B has a higher frequency

Seismic Waves

• Seismic waves are vibrations that travel through the Earth
• They are often caused by natural events like earthquakes or man-made activities such as explosions
• Body waves and surface waves are two types of seismic waves

Waves Moving Between Mediums

• Wave A is moving from medium 1 to medium 2.
• In its starting medium, Wave A has a longer wavelength and lower frequency
• In its ending medium, Wave A has a shorter wavelength and higher frequency

Body Waves

• Body waves travel through the Earth’s interior
• P-waves (Primary waves) are compressional waves that move quickly
• P-waves are the first to be detected by seismographs
• P-waves can travel through solids, liquids, and gases
• S-waves (Secondary waves) are shear waves that move slower than P-waves
• S-waves can only travel through solids

Surface Waves

• Surface waves travel along the Earth's surface and generally cause more damage during earthquakes
• Rayleigh waves create a rolling motion, similar to ocean waves
• Love waves cause the ground to move side to side, causing significant damage