Refraction of Light Part 2

1 / 32

# Refraction of Light Part 2 - PowerPoint PPT Presentation

Refraction of Light –Part 2. Internal Reflection. When light travels from a slow medium to a fast medium, the angle of refraction is larger than the angle of incidence. When the angle of refraction should be 90 o or greater, there is total internal reflection.

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

## PowerPoint Slideshow about 'Refraction of Light Part 2' - garron

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

### Refraction of Light –Part 2

Internal Reflection
• When light travels from a slow medium to a fast medium, the angle of refraction is larger than the angle of incidence.
• When the angle of refraction should be 90o or greater, there is total internal reflection.
• The incident angle which predicts a 90o refraction angle is called the critical angle.
• Applet
Critical Angle
• n1sin qc = n2 sin 90o
• n1sin qc = n2
• sin qc = n2 / n1
• qc = sin-1(n2 / n1)
• For water: qc = 48o
• The higher the index of refraction the lower qc
Internal Reflection
• All rays reflect internally, but the top three rays reflect only a small percentage internally; most energy leaves the prism.
• The fourth and fifth rays are reflected 100 % internally
Internal Reflection in Diamond
• The critical angle fordiamond in air is24.5 o.
• Any ray which strikes the inside surface at an angle greater than 24.5o will be totally internally reflected.
Rainbow Formation
• An observer seesred light comingfrom droplets ofwater higher inthe sky.
• Droplets of waterlower in the skysend violet lightto the eye.
Alexander’s Dark Band
• Sky is light inside primary rainbow
• Dark between primary and secondary bows
• Light beyond the secondary rainbow
• Dark region between is called Alexander’s Dark Band
22o Halo
• A halo is a ring of light surrounding the sun or moon.
• Most halos appear as bright white rings but in some instances, the dispersion of light as it passes through ice crystals found in upper level cirrus clouds can cause a halo to have color.

Diameter less than 20.5 micrometers

Randomly oriented hexagonal ice crystals

Sundogs
• Sundogs or parhelia on right and left of sun

Flat faces horizontally oriented

Hexagonal ice crystals

Diameter greater than 30 micrometers