1. Light and EM Spectrum
Light is all thanks to electrons…well… photons…but whatever.
What do you REALLY know about light?

2. “R O Y G B I V”
Frequency Increases
Wavelength Longer

3. Light Light is a kind of electromagnetic radiation.
Speed of light = 3.00 x 108 m/s, and is abbreviated “c”

4. Electromagnetic radiation moves through space as a wave moving at the speed of light.
c = speed of light, a constant (3.00 x 108 m/s)
Equation:
c =
 (lambda) = wavelength, in meters
(nu) = frequency, in units of hertz (hz or 1/sec)
Meters = meter x 1
Second Second

5. Wavelength and Frequency
Are inversely related
As one goes up the other goes down so that they always equal C.
c =
Different frequencies of light are the different sections of the light spectrum.

6. Practice
Calculate the wavelength of the yellow light emitted by a sodium lamp if the frequency of the radiation is 5.10x10^14 Hz.

7. Examples
What is the wavelength of blue light with a frequency of 8.3 x 1015 hz?
What is the frequency of red light with a wavelength of 4.2 x 10-5 m?

8. Explanation of atomic spectra
The energy level, where the electron starts from, is called its ground state - the lowest energy level.

9. Changing the energy
Let’s look at a hydrogen atom, with only one electron, and in its ground state.

10. Changing the energy
Heat, electricity, or light can move the electron up to different energy levels. The electron is now said to be “excited”

11. Changing the energy
As the electron falls back to the ground state, it gives the energy back as light

12. Changing the energy They may fall down in specific steps
Each step has a different energy

13. Light is a Particle? The pieces of light are called photons.
The energy they release is in units called quanta or quantum

14. Energy & frequency: directly related.
Ultraviolet
Visible
Infrared
The further they fall, more energy is released and the higher the frequency.
Energy & frequency: directly related.

16. Wavelengths
If an electron falls from n =4 to n= 2. What wavelength of light is emitted and what color is that light?
…this is where you really need that reference sheet.

17. Heisenberg Uncertainty Principle
It is impossible to know exactly the location and velocity of a particle.
The better we know one, the less we know the other.
Measuring changes the properties.
True in quantum mechanics, but not classical mechanics

18. This was a busy section…
How are wavelength and frequency related?
How are frequency and energy related?
Summarize in your own words.