warm up 10/21 where can electrons be found in an atom? what is their electric charge?
TRANSCRIPT
Warm Up 10/21
Where can electrons be found in an atom? What is their electric charge?
Lesson: Electcromagnetic Spectrum (EMS)
Parts of a wave
Wavelength – Distance between two corresponding points on successive waves.Amplitude – measure of a wave’s “strength” (height of crest or trough).
The Wave-like Electron
Louis deBroglie
The electron propagates through space as an
energy wave. To understand the atom, one must understand
the behavior of electromagnetic waves.
Electromagnetic Wave – An electric wave and magnetic wave moving at right angles to each other.
Electromagnetic Spectrum – Arrangement of all forms of electromagnetic radiation in order of frequency and wavelength.
• Frequency (ν): number of wavelengths that pass a certain point in a given amount of time.- units are Hertz (Hz)
• If these 2 waves are traveling at equal speeds, which wave will have more wavelengths cross the finish line in one minute?
FIN
ISHlow frequency
high frequency = short wavelength
= long wavelength
• If these 2 waves are traveling at equal speeds, which wave will have more wavelengths cross the finish line in one minute?
FIN
ISHlow frequency
high frequency = short wavelength
= long wavelength
Left Side Practice
1) Pick a type of wave on the EMS (not visible light). 2) Draw a pic of that wave and label the crest, trough, wavelength and amplitude.3) Write and answer these questions:• Does it have a greater wavelength than visible
light?• Does it have a higher frequency than visible
light?• Does it have more or less energy than visible
light?
3) Write and answer these questions:Does it have a greater wavelength than visible light?Does it have a higher frequency than visible light?Does it have more or less energy than visible light?
Warm Up 10/22
Which type of EM wave do you think travels the
fastest?
• Wavelength (λ) and frequency (f) are inversely related.
• All waves on the EMS travel at the speed of light (c).
c = λ (f)
• c = speed of light = 3.00 x 108 m/s.
o to solve for λ …c
λ = f
o to solve for f … c
f =λ
Practice
Calculate the f of a wave that has a wavelength of 5.00 x 10-6 m.
c
f =λ
f =
=f Hz
Does this radiation have a shorter or longer λ than red light?
What is the wavelength of radiation with a frequency of 1.50 x 1013 Hz?
c
λ = f λ =
λ =
Practice
Calculate the wavelength of yellow light emitted by a sodium lamp, if the frequency of the radiation is
5.10 x 1014 Hz.
On Your Own Practice
* Hint: Be sure you set up the right equation. Ask yourself: which variable am I solving for?