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CHAPTER 17 SCIENCE. SOUND AND LIGHT ENERGY. LESSON 1. Sound energy is caused by vibrations in matter, this vibration produces waves in the matter, this wave movement is called a compression wave Sound is omnidirectional Sound has two major properties; volume and frequency
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CHAPTER 17 SCIENCE SOUND AND LIGHT ENERGY
LESSON 1 • Sound energy is caused by vibrations in matter, this vibration produces waves in the matter, this wave movement is called a compression wave • Sound is omnidirectional • Sound has two major properties; volume and frequency • Volume is the loudness of sound ; it is measured in decibels • Decibels are calibrated in powers of ten, a 20 decibel sound is 100 times louder than a 10 decibel sound • Frequency of sound is the number of vibrations per second; frequency is measured in Hertz and described as wavelengths • Pitch is the lowness or highness of a sound
Lesson 1 continued • Sound wave energy can be absorbed and reflected; soft surfaces absorb, hard surfaces reflect and redirect (echoes) • Sounds from the same object can be adjusted in various ways e.g. striking, tension • Compression waves carry sound through air . • The sound energy transfers from particle to particle but the particles stay in place. • Sound needs a medium to carry the vibrations • The medium determines the rate of speed ;change the medium and the rate changes, warm air is faster than cold air, solids and liquids are better than gases
LESSON 2 • The sun is the source of light energy in our solar system • Light energy travels by waves, but does not need a medium to carry it. These waves are called radiation. • All the different waves are called the “electromagnetic spectrum” • The different wavelengths have differing amounts of energy but all travel at the same speed. The shorter the wave length the more energy that frequency has.
LESSON 2 CONTINUED • Light waves travel in straight lines unless interefered with . • Light can be bent (refracted), blocked, or redirected (reflected). • Light will bend when it passes throuh from one substance to another, e.g. air to water • When light is reflected its angle of incidence equals the angle of reflection
LESSON 2 CONTINUED • Opaque objects block, translucent lets some and transparent lets almost all light pass. • Lenses thicker in the middle than the edges (convex) focus light rays • Lenses thicker at the edges than the middle (concave) spread light rays