1. Atomic Theory Notes

2. Wave – Disturbance in a field which transfers energy
Waves
What is a wave?
Wave – Disturbance in a field which transfers energy
7:39 (6:40 is where the initial video ends)
Draw and label parts of a wave

3. Waves Why we believe light moves in waves.
Why we believe light moves in waves.
Extra:

4. Frequency - # of waves to go by in 1 second
Units are in Hz or Hertz
Electromagnetic Spectrum – Disturbance in electric and magnetic field

5. The speed of a wave: The speed of light: Waves
The speed of a wave:
Speed = Wave length x frequency
m/s m Hz
The speed of light:
C = λ x F
Speed of light = 3x108 meters/second
300,000,000 meters/second
3:44 minutes
300,000,000m/s = 670,000,000mph = 186,000 miles per second
25,000 miles = circumference of the Earth so in 1 second light will travel around the Earth 7.5 times!
It is 480,000 miles round trip to the moon so it takes light 2.6 seconds to go from here to the moon and back (tested with lasers)

6. Example Problems
Sound waves in air travel at approximately 330m/s. Calculate the frequency of a 2.5m-long sound wave.
A wave on a certain guitar string travels at a speed of 200m/s. Calculate the wavelength of an “A” note sounding at 440Hz.
f = 132Hz
= 0.45m

7. Example Problems
Find the wavelength of a wave traveling at 20 m/s at a frequency of 5 Hz.
Find the speed of a wave with a frequency of 8 Hz and a wavelength of 16 m.
4 meters
128 m/s

8. Light and Colors
All light has the same speed. How do we get different colors?
Light waves moving at different frequencies and having different wavelengths.
What colors can we get?
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Which has the smallest wavelength and which has the largest wavelength?
Smallest - Violet
Largest - Red

10. What color had the most energy?
Lab Discussion
What color had the most energy?
Blue in lab.
Overall Violet.
What kind of relationship is there between wavelength and energy?
Inverse relationship between wavelength and energy
As wavelength increases energy decreases
As wavelength decreases energy increases

11. Energy is like a ladder the higher you go the more energy you have.
Why do you have more energy when you are higher up on the ladder?
You have farther to fall.
Atoms work the same way the farther from the nucleus electrons go the more energy they have because it has a farther distance it can travel.
When electrons are at their lowest energy orbital possible we call it the ground state.

12. Out of the following list order the colors from most amount of energy down to the least:
______ Purple Light (400 nm) ______ Blue light (440 nm)
______ Red light (680 nm) ______ Teal light (520 nm)
If we were putting them on the above target identify which number goes with which color
Could we add green to the target?
No  Why?
There is not a separate ring/rung for it to go on.
Copy this table and diagram into your notes.

13. Spectrum
Order the following from least amount of energy to most amount of energy:
Visible light, radio waves, x-rays, UV rays, infrared light, gamma rays and microwaves

14. Low
Energy
High
Energy
Put the order in your notes

15. Electromagnetic Spectrum
2:14
5:03

17. Every wavelength has a certain amount of energy associated with it.
Planck
Every wavelength has a certain amount of energy associated with it.
Because of this we know light is not a continuous wave but instead a particle or photon.
Light is photons or quanta (small packets of energy/waves).

18. Planck’s Equation E = h x F h = 6.63x10-34 Js
Use if only frequency is given to you
We already know: C = λ x v
E = h x (c/λ)
Use if you know 2 of the following:
Speed
Wavelength
Energy
If frequency increases what happens to the amount of energy?

19. Example Problems
A photon has a frequency of 2.68 x 106 Hz. Calculate its energy.
A photon of light has a wavelength of cm. Calculate its energy.
Ans: E = 1.78 x J
Ans: E = 3.98 x J