Introduction to Waves

The location of energy sources may be different than where they

are needed.

• The energy must be transferred from one location to another by some means such as……

Movement of Material

• Ie. Projectiles in flight, wind, etc.

• When a ball hits a window, the glass is shattered by energy transferred from the ball during impact.

Thermal Convection

• Heat energy is transferred by thermal convection. This is the movement of quantities of heated gas or liquid between two locations.

Waves

• Ie. Sound waves, light waves, water waves, etc. The ideas and language used to describe waves are the same, regardless of the kinds of waves involved.

What is a wave?

• The basic concept in the use of the term wave is that the wave involves some quantity or disturbance that changes in magnitude with respect to time at a given location and changes in magnitude from place to place at a given time.

• A wave is a disturbance that propagates through a medium or space (vacuum).

Some waves are electromagnetic waves

• Electromagnetic waves can travel through a material or through a vacuum.

• Examples include visible light, microwaves, radio waves, x-rays, infrared rays and ultraviolet waves.

• V = 3.00 x 108 m/s in air or a vacuum

Some waves are mechanical waves

• Mechanical waves require a material medium for their propagation (movement).

• Sound waves, ocean waves, and earthquakes are mechanical waves.

• Mechanical waves can be transverse, longitudinal, or surface waves.

Transverse Waves

• A transverse wave is a wave in which the vibrations are at right angles to the direction of propagation.

• http://surendranath.tripod.com/Applets/Waves/Twave01/Twave01Applet.html

Longitudinal Waves

• A longitudinal wave is a wave in which the vibrations are parallel to the direction of propagation of the wave.

• http://www.glenbrook.k12.il.us/GBSSCI/PHYS/mmedia/waves/lw.html

Surface Waves

• Surface waves such as water waves combine longitudinal and transverse wave movement.

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es1604/es1604page01.cfm?chapter_no=visualization

Define the following wave terms

• Elastic medium• Disturbance• Pulse• Crest• Trough• Compression• rarefaction

• Speed• Frequency• Period• Wavelength• Amplitude• Phase