Upload
megan-cabrera
View
34
Download
0
Embed Size (px)
DESCRIPTION
Radiation – Electromagnetic Energy. PHY 299 Spring 2009 Bob Brecha. Light Waves. Light is a form of wave, like a water wave or a wave on a rope. But ... waves need something to “wave” ( e.g. water or rope or a crowd ) Light (electromagnetic) waves can also move through vacuum. - PowerPoint PPT Presentation
Citation preview
PHY 299 Spring 2009Bob Brecha
Light is a form of wave, like a water wave or a wave on a rope. But ...waves need something to “wave”(e.g. water or rope or a crowd)
Light (electromagnetic) waves can also move through vacuum.
Light waves are reallymade up of electric fields and magnetic fields - more on that later
Moving electric charges are the source for all electromagnetic waves.
wavelength
T
T period
The period of a wave is related to the wavelength of the wave. It is sometimes easier to talk about the “frequency” of the wave rather than the period
f = 1/T c = f ×
c = speed of light (300,000 km/sec.)
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
0.00E+00
1.00E-05
2.00E-05
3.00E-05
4.00E-05
5.00E-05
6.00E-05
7.00E-05
8.00E-05
Ra
dia
tio
n in
ten
sit
y
Wavelength
Blackbody radiation (300 K)
Low temperaturesLong wavelength radiation40ºC 10,000 nm peak (10 m)
High temperatures Shorter wavelength radiation6000 ºC 500 nm peak (0.5 m)
0.00E+00
5.00E-02
1.00E-01
1.50E-01
2.00E-01
2.50E-01
3.00E-01
3.50E-01
4.00E-01
4.50E-01
0.00E+00
1.00E-05
2.00E-05
3.00E-05
4.00E-05
5.00E-05
6.00E-05
7.00E-05
8.00E-05
Radi
atio
n in
tens
ity
Wavelength
Blackbody radiation (300 K)