1. EM Plane Wave: z Wave propagates along k, magnitude = 2p/l
E and B constant on planar “phase front” k
E and B are in phase E B x y

2. Energy density (J/m3) in an electrostatic field:
Energy density (J/m3) in an magnetostatic field:
Energy density in an electromagnetic wave is equally divided:

3. Rate of energy transport: Power (W)
John Henry Poynting
Rate of energy transport: Power (W) A
cDt
Power per unit area (W/m2):
Pointing Vector
Poynting

4. Poynting Vector oscillates very rapidly!
Take the time average:
“Irradiance” (W/m2)

5. EM radiation carries momentum:
absorber
Radiation pressure

6. Light is really made up of particles - photons
absorber
They carry energy:
and momentum:
“H-bar” is Planck’s constant:

7. Radiometry: the measurement of EM radiation Radiant Power Fe W
Radiant Exitance Me
W/m2
Irradiance Ee
Radiant Intensity Ie
W/sr
Radiance (brightness) Le
W/sr-m2 Le Me Fe Ee Ie W

8. Gamma ray
X-ray UV
Infrared
radar
radio
l (meters)
10-15
10-12
10-9
10-6
10-3 1
103
Visible Light
400 nm
700 nm

9. Photometry: the measurement of EM radiation as perceived by the eye.
equal radiance
Luminous efficiency 1
(me)
V(l)
(you)
400 nm
700 nm
(administrator)

10. Luminous Flux Fv
lumen (lm)
Luminous Exitance Mv
lm/m2
Illuminance Ev
lm/m2 or lux (lx)
Luminous Intensity Iv
lm/sr or candela (cd)
Luminance (brightness) Lv
cd/m2 or nit
(Photometric value) = 685 x V(l) x (radiometric value)