METR 415/715

1 / 7

# METR 415/715 - PowerPoint PPT Presentation

METR 415/715. Wednesday February 6 2013. Imaginary part of index of refraction. When n i is non-zero, absorption of an EM wave occurs as it passes through a medium. n i is sometimes referred to as the absorption index n i depends on the wavelength

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'METR 415/715' - fearghus-frain

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### METR 415/715

Wednesday February 6 2013

Imaginary part of index of refraction
• When ni is non-zero, absorption of an EM wave occurs as it passes through a medium.
• ni is sometimes referred to as the absorption index
• nidepends on the wavelength
• Figure 4.1 (page 77) shows values of nifor water and ice – small for visible and higher for UV and IR
Intensity as a function of travel through a medium
• Eq 4.2, p.77
• Βa= absorption coefficient
Transmittance t
• The fraction of radiation intensity that survives the trip over the distance x.
• The fraction that was NOT transmitted must have been absorbed and thereofre converted to another form of energy such as heat
Beer’s Law
• The intensity of a beam of monochromatic radiation falls off exponentially as it traverses a uniform medium
• The rate at which it falls off is proportional to βa
Penetration Depth
• Defined as the value of x for which

t(x) = e-1 or approximately 37%

• Check Figure 4.2 on page 79 for water and ice

• How does that influence color of pools water? Light penetration into the ocean?