Waves Mechanical

Introduction to Wave pt 3: EM vs Mechanical Waves

by Ms Taylor

​Types of Waves

• Waves may be categorized based on whether or not they need a medium.

• ​There are two types of waves:

  • 1.) Mechanical waves: require a medium (matter) to travel.

    2.) Electromagnetic (EM) waves: do NOT require a medium to travel.

​Mechanical waves

• ​These require a medium for the vibrations to travel and so cannot travel through space (vacuum)

• ​

• ​May either move as transverse or longitudinal waves.

• ​

• ​Ex. sound, water wave, slinky,

​​Mechanical waves

• ​The speed at which they travel depends on either the type of wave or the medium they are in.

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• ​They travel fastest in more dense medium. Therefore, they move fastest in solids and slowest in gases.

• ​

• ​Generally, these have longer wavelengths than electromagnetic waves.

​Electromagnetic Wave

• ​A waves that does NOT require a medium (matter to travel), has an electric field component and a magnetic field component.

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• ​These two fields move perpendicular to the propagation of the wave and so they are all transverse waves

​Electromagnetic waves

• ​All electromagnetic waves travels at the speed of light 3.0 x 10⁸ m/s in a VACUUM. However, they travels at different speeds when traveling through matter.

• They travel fastest in less dense medium, so fastest in gases and slowest in solids.

• Ex: Radio waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, and Gamma Ray.

​Electromagnetic Spectrum

• ​Shows a visual display of various electromagnetic waves to compare their relative wavelengths and frequencies.

Multiple Choice

What is a medium?

• Gases

• Solids

• Liquids

• All of these are mediums of "matter"

Multiple Choice

The most important question that can be asked to determine the difference between electromagnetic waves and mechanical waves has to do with...

• The waves energy

• Requiring a medium

• The wavelength

• Having a high Frequency

Multiple Choice

Which type of waves must have a medium in order to travel?

• electromagnetic wave

• mechanical wave

Multiple Choice

Mechanical waves usually travel fastest through:

• solids

• liquids

• gases

Multiple Choice

What type of wave is this?

• Electromagnetic

• Mechancial

• Both Electromagnetic and Mechanical

Multiple Choice

A microwave is an example of what type of wave?

• electromagnetic wave

• mechanical wave

Multiple Choice

A water wave is an example of what type of wave?

• electromagnetic wave

• mechanical wave

Multiple Choice

Wave with the longest wavelength

• microwave
• radio
• gamma
• visible light

Multiple Choice

When the wavelength increases the frequency will

• increase

• decrease

• remain same

• none of these

Multiple Choice

Electromagnetic waves  

• Must travel through a vacuum
• Can travel through a medium or a vacuum
• Are the same type of wave as mechanical waves
• Can only travel through a vacuum

Multiple Choice

How are light and sound similar?

• Speed

• traveling through a vacuum

• Being electromagnetic

• Waves

Multiple Choice

All electromagnetic waves have the same...

• frequency
• speed
• wavelength
• energy

Multiple Choice

When a wave is travelling through matter, what happens to the matter?

• The matter is pulled along behind the wave as that makes it a longitudinal wave.

• The wave is making the matter move back and forth as that will make a transverse wave.

• The wave is making the matter move up and down.

• The matter is pulled along behind the wave as that makes it a compressional wave.

• The matter does not move along with the wave.

Multiple Choice

It depends on the medium in which the wave is traveling. It varies in solids, liquids and gases.

• Frequency

• Wave speed

• Amplitude

• Wavelength

Multiple Choice

Which wave in the diagram has the greatest wavelength?

• 1

• 2

• 3

• 4