1. Lesson 7 Notes
Modeling Light

2. I. Waves
Rhythmic disturbances that carry energy without carrying matter.
Two Types
Mechanical
Electomagnetic

3. II. Mechanical Use matter to transfer energy Matter is called medium
Two Types:
Transverse
Matter moves at right angles to the direction the wave is traveling
High points = crests
Low points = troughs
Example: movement of a rope
Compressional
Matter moves in the same direction as the wave travels
Ex: Sound waves

4. III. Electromagnetic Waves
Transverse waves produced by the motion of electrically charged particles
do not require matter to carry energy
Ex: Radio waves, infrared, visible light, ultra violent light
Can travel through space (mechanical cannnot)

5. IV. Amplitude of Waves Related to energy waves carry
Bright light has a greater amplitude than dim light
Loud sound has a greater amplitude than soft sounds

6. V. Wavelength Distance from crest to crest (transverse waves)
Distance from center of one compression to the center of the next (compressional waves)

7. VI. Frequency # of wavelengths in a given second
Measured in Hertz: (Hz)
Longer wavelengths  shorter frequencies
Light travels faster than sound
Sound waves travel faster in solids than liquids and gases (atoms closer together)
Light travels faster in gases (less atoms)

8. VII. Terms
Reflection: A wave strikes an object or surface and bounces off
Example: echo is a reflected sound
Refraction: Bending of a wave as it moves from one medium into another; Speed of wave changes as it passes from one substance to another
Diffraction: Bending of waves around a barrier
Interference: Two waves combine and form a new wave when they overlap
distructive: crest crosses with trough
Constructive: two crests overlap