wave -- particles do not move with the wave, only energy

medium -- the matter or substance through which a wave is transmitted
 

Types of Waves

1.  transverse waves -- particles in the wave vibrate at right angles to its direction of motion
                                ex. light, waves in a rope

2.  longitudinal waves -- particles in the wave move parallel to the direction of motion
                                        ex.  sound

More on longitudinal waves
 

rarefaction -- area of a wave where the particles are                       spread apart compression -- area of the wave where the particles are                          crowded together

More on transverse waves
 
 

crest -- highest point on the wave trough -- lowest point on the wave amplitude -- 1/2 the distance between the crest and trough of a wave wavelength -- distance between corresponding points on side by side waves (like from crest to crest or trough to trough) (measured in meters)

frequency -- the number of waves which pass a point in one second (measured in hertz) (Hz)

Calculating the Speed of a Wave

velocity = frequency X wavelength

Problem:   What is the speed of a wave with a frequency of 100 Hz and a wavelength of 15 m?

v = ?

f = 100 Hz

wavelength = 15 m

v = frequency X wavelength

v = 100 Hz X 15 m

v = 1,500 m/s

{Some Properties of Light Waves}

1.   Light waves travel away from a source in straight lines called rays. (indicates light has particle properties)
2.   Light also has wave properties
3..  The amount of light falling on a surface increases as the intensity of the source increases.
4.   The amount of light falling on a surface decreases as the distance from the source increases.

illumination -- the amount of light falling on a surface

** When light strikes a surface some light rays will be reflected, some will be absorbed, and some may be
   transmitted.
 
 

reflection -- the bouncing of a wave off from the surface

absorbed -- wave is taken into the surface it strikes

transmitted -- wave passes through the surface it strikes
 
 

[Law of Reflection] The angle of incidence of a light ray is equal to its angle of reflection. angle of incidence -- the angle the light ray makes with the surface it hits angle of reflection -- the angle the light ray makes with the surface it reflects from

 

Plane Mirrors reflect light in a regular pattern.

The images formed by plane mirrors are right side up, the same
size as the object, and appear to be as far behind the mirror as the object is in front of the mirror.

Images formed by a plane mirror are reversed. (backward)

medium -- a material through which light can pass (media is the plural)

interface -- the boundary between two media

normal -- an imaginary line on a light ray diagram drawn at right angles to the interface

** Light rays bend as the pass from one material into another.

refraction -- the bending of light rays or any wave

[Law of Refraction]

When a light ray enters a medium and its speed decreases, the ray is bent toward the normal.
When a light ray enters a material and its speed increases, the ray is bent away
from the normal.

Lenses are used to refract light rays

convex lenses -- bend light rays together to a focus (converging lenses)

concave lenses -- bend light rays apart (diverging lenses)

Images formed by lenses may be inverted.  (upside down)

Lenses may form images larger, the same size, or smaller than the object in view,
depending upon the distance of the object from the lens.

dispersion -- the spreading of white light into its component colors when it passes through a prism
                      (a complex example of diffraction)

ex.  a rainbow is an example of dispersion in nature
 

To see an object, light from that object, emitted by or reflected from it, must enter the eye.

interference -- occurs when two (or more) waves meet in a medium

a.)  constructive interference -- crest of one wave meets the crest of another wave

b.)  destructive interference -- trough of one wave meets the crest of another wave

Different forms of electromagnetic energy have different wavelengths.

As can be seen in the diagram above, some examples of electromagnetic energy include gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

Visible light occupies just the small center region of the wavelengths of the electromagnetic spectrum.

Visible light has the following component colors.

   Red            Orange          Yellow          Green              Blue            Violet