What is a Wave? Sound and Light are forms of energy that travel in waves A wave is a repeating disturbance or movement that transfers energy through matter or space All waves are produced by something that vibrates Waves carry and transfer energy from one place to another Some waves need a medium to travel through, while others can move through empty space, known as a vacuum. A medium is a material through which a wave travels (solid, liquid, or gas)

Types of Waves Mechanical Waves are waves that travel only through matter –Transverse wave – a wave in which particles of the medium move up and down at right angles to the direction that the wave travels Ex. Water waves –Compressional wave – a wave in which particles of the medium move back and forth in the direction of the wave motion in the same direction that the wave travels In this wave, the particles compress and then spread apart as a way to pass on energy (also called longitudinal waves) Examples : Sound waves, slinkies Electromagnetic Waves – are waves made by vibrating electric charges and can travel through space Examples: Visible light, radio waves, UV rays, Infrared

Mechanical Waves Compressional Wave Transverse Wave Compression – part of a medium where particles are close together Rarefaction –part of a medium where particles are far apart

Electromagnetic Waves The electric field is perpendicular to the magnetic field

Parts of a Wave Crest Wavelength Trough Normal Rest Position Frequency = 2 waves per second

What are the parts of the wave? Crest – highest point of a wave Trough - lowest point of a wave Wavelength – the distance between two crests or two troughs Frequency – how many wavelengths pass a fixed point each second –Expressed in Hertz (Hz) –As frequency increases, wavelength decreases Amplitude – height of a wave, or the amount of energy in a wave Rest position (equilibrium) – describes a wave at rest, not passing on energy

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