Forms of Energy Description A. Energy is involved in all physical processes and is a unifying concept in many areas of science. B. Energy exists in many forms and has the ability to do work or cause a change.

Benchmark Number & Descriptor SC.7.P.10.1 Illustrate that the sun's energy arrives as radiation with a wide range of wavelengths, including infrared, visible, and ultraviolet, and that white light is made up of a spectrum of many different colors. SC.7.P.10.2 Observe and explain that light can be reflected, refracted, and/or absorbed. SC.7.P.10.3 Recognize that light waves, sound waves, and other waves move at different speeds in different materials.

NATURE OF WAVES Waves (Def.) – A disturbance that transfers energy Medium – Substance through which a wave moves through Speed of Waves – Depends on the properties of the medium

What are the parts of a wave? Transverse wave The crest = highest point on a transverse wave The trough = lowest point on a transverse wave The wavelength is the distance from one point on the wave to the next corresponding adjacent point EX: Trough to trough Crest to crest

What are the parts of a wave? Compressional (Longitudinal) Wave Compression = Tightly coiled section Refraction = Loose, less coiled section Wavelength = the distance from one point on the wave to the next corresponding adjacent point

.. WAVELENGTH and FREQUENCY What is wavelength?What is wave frequency? The distance from one point on the wave to the next corresponding adjacent point The smaller the wavelength, the more times it will pass through a point in one second The larger the wavelength, the fewer times it will pass through a point in one second Frequency is the number of waves that pass through a point in one second. The unit for frequency is waves per second or Hertz (Hz). One Hz = One wave per second. Wavelength and frequency are inversely related.

What is the amplitude of a wave? Transverse Wave Height of crest trough from standstill Larger the height, greater the energy Compressional Wave Greater amplitude = Tighter coils Less amplitude = Loose coils

1. How does the frequency of a wave relate to its wavelength? 2. Name two types of waves. 3. Name two parts of each wave. 4. How is amplitude of a longitudinal wave measured? KNOWLEDGE CHECK

1. How does the frequency of a wave relate to its wavelength? The greater the frequency, the smaller the wavelength. 2. Name two types of waves? Longitudinal and Transverse 3. Name two parts of each wave. Longitudinal = Compression/Rarefaction Transverse = Crest/trough 4. How is amplitude of a longitudinal wave measured? Based on the tightness of the coils KNOWLEDGE CHECK

We see things because they reflect light into our eyes: Homework

Electromagnetic Spectrum Visible Spectrum – Light we can see Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet Largest to Smallest Wavelength

Light Our primary source of light is the sun. Light travels in straight lines at a speed of 186,000 miles per second. Light waves travel faster than sound waves! Light energy from the sun travels through space, reaches earth, and some of it turns to heat energy and warms the earth’s air. Light from the sun also travels to the cells of green plants (producers) and is stored as energy. When light reaches an object, it is absorbed, reflected, or passes through it.

1. What is the order of the Electromagnetic Spectrum? 2. What is our major source of light energy? 3. Which travels faster, light or sound? KNOWLEDGE CHECK

1. What is the order of the Electromagnetic Spectrum? ROY G. BIV (red, orange, yellow, green, blue, indigo, violet) 2. What is our major source of light energy? The Sun 3. Which travels faster, light or sound? Light waves KNOWLEDGE CHECK

How Waves React

Reflection A bouncing back of a wave after it hits a barrier Does not go through a barrier Echo = reflection of a sound wave Incident ray Reflected ray Mirror

REFRACTION Bend a wave at an angle as it hits a medium/barrier Light waves -> Prism -> Rainbow Light (colors) have a different wavelength; a prism breaks them apart.

Transparent objects: The windows on a school bus A clear empty glass A clear window pane The lenses of some eyeglasses Clear plastic wrap The glass on a clock A hand lens Colored glass ALL of these are transparent. We can see through them because light passes through each of them.

Translucent objects All of these materials are translucent. Allow some light to pass but the light cannot be clearly seen through. Thin tissue paper Waxed paper Tinted car windows Frosted glass Clouds

Opaque objects Heavy weight paper Cardboard Aluminum foil Mirror, bricks, buildings Your eyelids and hands Solid wood door All of these objects are opaque because light cannot pass through them at all. They cast a dark shadow.

1. Name a material that is opaque and reflects light waves? 2. Name a material that is transparent and refracts the light waves? 3. Name a material that is translucent and scatters light waves? KNOWLEDGE CHECK

1. Name a material that is opaque and reflects light waves? Mirror 2. Name a material that is transparent and refracts the light waves? Water 3. Name a material that is translucent and scatters light waves? Clouds KNOWLEDGE CHECK

SOUND WAVES

We hear sound which usually travels through air. Sound can travel through other mediums such as water and various solids. Sound travels different speeds through different mediums. Sound generally travels faster in a solid than a liquid and faster in a liquid than a gas. The denser the medium, the faster sound will travel. The higher the temperature, the faster the particles of the medium will move and the faster the particles will carry the sound.

What is sound intensity? Sound intensity is the energy that the sound wave possesses. The greater the intensity of sound the farther the sound will travel and the louder the sound will appear. Loudness is very closely related to intensity. Loudness is the human perception of the sound intensity. The unit for loudness is decibels.

How is frequency related to pitch? The pitch of a sound wave is directly related to frequency. A high-pitched sound has a high frequency. ex. screaming girl A low-pitched sound has a low frequency. ex. fog-horn A healthy human ear can hear frequencies in the range of 20 Hz to 20,000 Hz. Humans cannot hear below 20 Hz. Sounds below this frequency are termed infrasonic. Sounds above 20,000 Hz are termed ultrasonic. Some animals, such as dogs, can hear frequencies in this range in which humans cannot hear.

Loudness in Decibels

1. What type of matter does sound travel best through? 2. How does temperature affect the speed of sound? 3. What is the relationship between pitch and frequency? KNOWLEDGE CHECK

1. What type of matter does sound travel best through? Solids 2. How does temperature affect the speed of sound? The higher the temperature, the faster the sound will travel. 3. What is the relationship between pitch and frequency? Pitch and frequency are directly related. KNOWLEDGE CHECK