1. Electromagnetic Spectrum
Review

2. Frequency
Sometimes it is more convenient to talk about light’s frequency
Frequency (or f) is the number of wave crests that pass a given point in 1 second (measured in Hertz, Hz)
Important relation: fl = c
Long wavelenth = low frequency
Short wavelength = high frequency

3. fl = c  Huh?

4. Properties NO MASS TRAVELS AT THE SPEED OF LIGHT IN A VACUUM
MOVES IN BUNDLES OF ENERGY CALLED PHOTONS
AS FREQUENCY INCREASES, ENERGY OF PHOTONS INCREASES

5. Waves
Wavelength
Crest
Wave Height
Trough

6. Wavelength determines type of EM

8. Light and Color The nanometer (10-9 m) is the convenient unit
Red = 700 nm (longest visible wavelength), violet = 400 nm (shortest visible wavelength)
Colors to which the human eye is sensitive is referred to as the visible spectrum
In the wave theory, color is determined by the light’s wavelength (symbolized as l)

9. Low Energy High Energy Long wavelength Short wavelength
Low frequency High frequency

10. Rankings Radio Longest Lowest Lowest Microwave Infrared Visible
Wavelength Frequency Energy
Radio Longest Lowest Lowest
Microwave
Infrared
Visible
Ultraviolet
X-ray
Gamma Ray
Cosmic Ray Shortest Highest Highest

11. Radiation and Temperature
As an object’s temperature increases, the object radiates light more strongly at shorter wavelengths.
Blue has more energy than red.

12. Hydrogen spectrum 410 nm 434 nm 486 nm 656 nm
Emission spectrum because these are the colors it gives off or emits.
Called a line spectrum.
There are just a few discrete lines showing
410 nm
434 nm
486 nm
656 nm
Hydrogen spectrum

13. Different elements have different spectra…like fingerprints for elements

14. The Visible Spectrum

15. Different types of spectra
Continuous spectrum
All colors present
Emission-line spectrum
Produced by hot gases
Only certain wavelengths appear
Absorption-line spectrum
A spectrum with dark lines missing
Caused by atoms absorbing certain wavelengths
Same wavelengths as found in emission spectra for the same atom

16. Hydrogen Continuous Spectrum Absorption-line spectrum for Hydrogen
Emission-line spectrum for Hydrogen

17. Our Sun’s Spectrum
All of the dark lines represent the different elements in our Sun (67 or so)

18. Doppler Effect
Waves are compressed and stretched depending on how the source is moving

19. Doppler Effect
Blue Shift Red Shift
Coming towards Going away

20. In your ISN Label the electromagnetic spectrum
(Include wavelengths, frequency, types of radiation, and an example for each)
Draw and label a continuous line spectrum, absorption, and emission line spectrum