Mr. Perez

 Intensity  Loudness  Pitch  Decibel  Transparent  Translucent  opaque

 Sound waves  Are longitudinal waves  Travel fastest in solids, then liquids and slowest in gases  Travel faster in warmer media than cooler media

 Intensity: the amount of energy that a wave carries past a unit area each second  Related to amplitude (large amplitude, large intensity)  Loudness: human perception of intensity of sound waves  Measured in decibels (dB)

 Pitch: human perception of the frequency of sound  Low frequency = low pitch  High frequency = high pitch

 The ear is divided into three parts: 1. Outer ear: collect sounds 2. Middle ear: amplifies sounds 3. Inner ear: interprets sounds

 Electromagnetic waves, such as light, can travel through empty space  In empty space, the speed of light is 300,000 km/s  Light travels the fastest in empty space and the slowest in solids  The wavelength of light and other electromagnetic waves is so small, that we measure it in nanometers (nm) 1 nm = 1 billionth of a meter = m

 Objects have color because some light waves reflect off of them  A red apple is red because red wavelengths bounce off it (red is emitted from the apple)  Light enters the eye through the cornea and transparent lens and then hits the retina and optic nerve  The retina is made up of:  Rods: sensitive to dim light  Cones: sensitive to color

 Transparent: when almost all the light passes through a material  Water, air, glass  Translucent: when only some light passes through a material  Plastics, frosted glass, wax paper  Opaque: when no light passes through a materials  Wood, stone, metals

 ps07.sci.phys.energy.lightpigment/ ps07.sci.phys.energy.lightpigment/

 Florida Science Grade 7, Glencoe Science & McGraw Hill Publishing  Google image search