8th Grade Science 09/24/2014  Essential Question - How does a wave transfer energy?  Objectives - I can...  Describe the relationship between the frequency and wavelength of a wave  Explain why waves travel at different speeds.  Bell Ringer - Copy and answer the following question on your bell ringer sheet.  How are mechanical waves and electromagnetic waves different? How are they alike?

Frequency, Amplitude, and Wavelength 8TH GRADE SCIENCE

Waves Review  A wave is a traveling disturbance that carries energy from one place to another.  Energy is the ability to do work or cause a change

Amplitude  Amplitude - is measured from the equilibrium position to the top of a crest or the bottom of a trough.  The amplitude of a transverse wave is a measure of how high the crests are or how deep the troughs are.

Wavelength  Another way to describe a wave is by its wavelength.  The highest points of waves are called crests.  The lowest points of waves are called troughs.  A wavelength, for a transverse wave, is the distance from one crest to the next.  A wavelength, for a compressional wave, is the distance between the center of one compression and the center of the next compression.

The Electromagnetic Spectrum:

Wavelength  Visible light is only a small part of the electromagnetic spectrum.  It is the wavelength of visible light waves that determines their color.  For example –  The wavelength of red light waves is longer than the wavelength of green light waves.

Frequency  Frequency is number of complete wavelengths in a given point.  As a wave length increases in size, its frequency and energy decrease.

8 th Grade Science 09/24/2014  Essential Question - How does a wave transfer energy?  Objectives - I can...  Describe the relationship between the frequency and wavelength of a wave  Explain why waves travel at different speeds.  Bell Ringer - Copy and answer the following question on your bell ringer sheet.  How does increasing energy affect the frequency and wave length of a wave? (hint – Think about the turtle and Rabbit picture)

Frequency and Energy  As a wave length increases in size, its frequency and energy decrease.  As a wavelength decreases in size, its frequency and energy increase.

Agenda 1. Review wavelength, amplitude, and frequency. 2. Notes on speed of waves 3. Begin Wave worksheet 4. Correct quizzes and complete reflection sheet

Review  Amplitude – the measurement from the top of the crest, or bottom of the trough, to the middle (equilibrium)  Wavelength – The length of a single wave cycle  Frequency – the number of waves that pass a given point in a given amount of time.

Speed of Waves  To calculate the speed of the wave, use the formula: Wave speed = Wavelength X frequency 10 cm

Calculate the speed of the wave 5 cm a. Wavelength _______ b. Amplitude _________ c. Frequency _______ d. Speed_________