Catalyst 112912 Draw the Bohr model of a
Catalyst 11/29/12 Draw the Bohr model of a Chromium atom. How many protons does the most common isotope of uranium have? How many neutrons?
Agenda 11/29/12 Catalyst Announcements Purchase spiral notebook ASAP! HW: Create a Quick. Study sheet for Packet#3 Material DUE MONDAY, 12/3/12 Introduction to the Properties of Light Class Practice Exit Slip
Class Points Your class can earn class points if: everyone in class: Comes to class quietly and on time Stays focused and on task during class Leaves classroom neat and organized Students are teaching other students Majority of class participates Follows all classroom P 3: 18 pts (on time and focused) P 4: 17 pts ( on time and focused) P 6: 18 pts (on time and focused)
Take out your notebooks! If you don’t have one, take notes on your i. Pad or on a separate piece of paper. You will eventually need to transfer it to a notebook so get one ASAP. During these types of lessons: DO NOT COPY DOWN EVERYTHING. Only important points and formulas! Highly recommend CORNELL STYLE
Objective We will be able to explain the mathematical relationship among the speed, wavelength and frequency of electromagnetic radiation.
INSERT VIDEO – ELECTROMAGNETIC SPECTRUM INTRO http: //www. youtube. com/watch? v=cf. Xzwh 3 Kad. E
Defining a Wavelength distance from CREST to CREST Frequency - cycles per second; how many peaks pass a given point in 1 second
WAVELENGTH l distance between any two peaks/crests on a wave Units = m
UNITS What are the units on wavelength What is Measured Unit(s) Symbol(s) Wavelength m λ
FREQUENCY f cycles per second; how many peaks pass a given point in 1 second Units = 1/s or Hz
UNITS What are the units on frequency What is Measured Unit(s) Symbol(s) Frequency 1/s or Hz f
v=l x f Velocity = wavelength multiplied by frequency Units = m/s
Understanding Waves • Transverse Waves - displacement is perpendicular to the direction of motion of the wave • Example: Light • Snake
Light is an Electromagnetic Wave
Special Things About a Light Wave • It does not need a medium through which to travel • It travels with its highest velocity in a vacuum • Its highest velocity is the speed of light, c, equal to 300, 000 km/sec • The frequency (or wavelength) of the wave determines whether we call it radio, infrared, visible, ultraviolet, X-ray or gamma-ray.
Frequency vs. Wavelength
EM Radiation Travels as a Wave c = 3 x 108 m/s It’s not just a good idea, it’s the law!
EM Spectrum Probes the Universe
Frequency and Wavelength Calculations The wavelength of the green light from a traffic signal is centered at 522 nanometers. (1 nanometer = 1 x 10 -9 meter). What is the frequency of this radiation?
You Try! Your cellphone emits a radiowave with a frequency of 2100 MHz. Calculate the wavelength of this microwave. (1 Megahertz = 1 x 106 Hertz).
Fun problem! A cell phone tower in Elizabeth emits an electromagnetic wave with a frequency of 2100 MHz. Will this wave reach Overlook Hospital in Summit, NJ? (1 Megahertz = 1 x 106 Hertz).
Exit Slip (Quietly and Independently) Complete on Notability and email this to me by the end of the period. 1. Light is considered to be a _________ wave. 2. What is the relationship between wavelength and frequency? 3. Calculate the frequency of a wave with a wavelength of 900 nm. (1 nm = 10 -6 m). Show all your work.
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