Mechanical and Electromagnetic Waves

• Waves can be categorized as mechanical or electromagnetic.

Mechanical vs. Electromagnetic Waves

• Mechanical waves need a medium such as solids, liquids, or gases to propagate.
• Examples of mechanical waves include sound, ocean waves, and compression waves.
• Electromagnetic waves do not require a medium and can travel through a vacuum.
• Examples of electromagnetic waves include radio waves, infrared, visible light, and X-rays.
• Electromagnetic waves have both electric and magnetic components.
• Mechanical waves transfer energy through matter.

Electromagnetic Spectrum & Light

• Longer wavelengths correspond to lower energy.
• Shorter wavelengths correspond to higher energy.
• Infrared light has a longer wavelength than visible light.
• Gamma rays, X-rays, and UV rays have shorter wavelengths and can cause DNA damage.
• White light splits into the visible spectrum when passing through a prism, creating a rainbow effect.
• Refraction occurs when white light splits into the visible spectrum after passing through a prism.

Sound Waves

• Sound is a mechanical, longitudinal wave.
• Sound requires a medium to travel.
• Sound travels faster in solids and slower in gases.
• Sound travels fastest in aluminum and slowest in air.
• Bats and porpoises use ultrasound for echolocation to detect objects.
• Sound travels faster in water than in air, so porpoises hear echoes first.

Wave Properties

• Amplitude is the height of a wave and is related to its energy.
• Greater amplitude means more energy.
• Frequency measures the number of waves passing a point per second.
• Wavelength is the distance between two crests or troughs of a wave.
• Shorter wavelengths mean higher frequency and more energy.

Wave Types

• Transverse waves have energy moving perpendicular to the wave direction.
• Light is an example of a transverse wave.
• Longitudinal waves have energy moving parallel to the wave direction.
• Sound is an example of a longitudinal wave.

Light and Lenses

• Refraction is the bending of light as it passes through materials such as glass or water.
• Refraction causes objects underwater to appear displaced.
• Lenses use refraction to magnify objects.

Quick Match Terms

• Electromagnetic waves travel in a vacuum and consist of electric and magnetic components.
• Mechanical waves require a medium and transfer energy through matter.
• Transverse waves have energy that moves perpendicularly to the wave's direction.
• Longitudinal waves have energy that moves in the same direction as the wave's movement.
• The visible spectrum is the range of colors seen when light is split.
• Refraction is the bending of light through different materials.
• Ultrasound is high-frequency sound used in echolocation.