Lecture video notes from Mr. Alexander: https://www.youtube.com/watch?v=mfMYw8LBrLw
GOALS: SWBAT
1. memorize the relationship between frequency and period
2. solve problems involving wavelength, period, and frequency
WARM-UP
1. What is the relationship between frequency and period?
2. A wave is introduced into a thin wire held tight at each end. It has an amplitude of 3.8 cm, a frequency of 51.2 Hz and a distance from a crest to the neighboring trough of 12.8 cm. Determine the period of such a wave.
a. which info is irrevelant?
b. solve the problem
CLASSWORK
1. 145A: Frequency & Period Practice Problems
Watch this great video from The Science Classroom showing how to use the wave equation to solve three common math problems. https://www.youtube.com/watch?v=3-wSHmXB64o
Read the text, then Solve "Check Your Understanding" #2-11
Each problem should take 30-90 seconds
LINK: https://www.physicsclassroom.com/class/waves/Lesson-2/Frequency-and-Period-of-a-Wave
2. 145B: Wave Speed Practice Problems
Watch this video from Bozeman Science on wave speed, how waves transfer energy, and why we need to know about frequency and period to solve for that. Really interesting into relating wave speed to lightning and thunder: https://www.youtube.com/watch?v=1E5IcxtWktc
Read the text, then Solve "Check Your Understanding" #1-9
Each problem should take 30-120 seconds
LINK: https://www.physicsclassroom.com/class/waves/Lesson-2/The-Speed-of-a-Wave
LEARNING AT HOME (HW)/Announcements
Quiz coming Friday, so you'll want your wave math skills to be sharp.
Also, I'll be adding some quiz retakes today...
ESSENTIAL QUESTION: How can I prove that light is a wave?
Goals:
1. SWBAT list two facts which prove light is a wave
2. understand the ordering of the frequency, wavelength, and energy for the various regions in the continuous spectrum for electromagnetic waves and visible light waves
WARM-UP:
1. 1 nm is 1 nanometer, which is 1 billionth of a meter, or 1x10-9m, or 0.000000001m
2. The acronym ROYGBIV is used to help order the relative wavelength of colors of light. Red is ~650nm, and Violet is ~420nm.
a. Does the order go from low to high, or high to low?
b. Would it make sense for Green to be 670nm? Why?
CLASSWORK:
1. 145A and B: Slideshow link ----->LINK (20min, then 10min review)
Consider that different frequencies of sound waves make different pitch sounds (high, low, and in-between)
How does the fact that different frequencies make different colors prove that light is a wave?
2. Polarization Demo (5 min)
How does polarization prove that light is a wave?
Demos:
- waves thru fenceposts
- paper thru fenceposts
- polarized glasses (fenceposts) viewing vertically oriented waves from a LCD screen
- https://www.youtube.com/watch?v=dUA6nyvy-LY
HOMEWORK
Draw the flame, label the hottest and coldest parts/colors. compare those parts to the wavelengths for each color. Is there a similarity in the pattern?
145D The Electromagnetic and Visible Spectra:
To prepare for tomorrow's class, read: http://www.physicsclassroom.com/Class/light/u12l2a.html
Take notes, and answer the three questions on Schoology (the assignment is in the Materials section)
***Quiz on sound waves & waves/musical instruments Friday