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Total Internal Reflection. Refraction Review. Refraction means bending. How does light go through glass anyway? Does NOT go through! Absorbed & Re-emitted countless times. Glass Molecules. Photon of light. Gulp!. Gulp!. Gulp!. Gulp!. BURP!. BURP!. BURP!. BURP!. - PowerPoint PPT Presentation
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Total Internal Reflection
Refraction Review
• Refraction means bending.
• How does light go through glass anyway?–Does NOT go through!
–Absorbed & Re-emitted countless times.
Glass MoleculesPhoton of light Gulp!
BURP!
Gulp! Gulp!
BURP!
BURP!
BURP!
Gulp!
Total Internal Reflection: Shine a light upwards out of water:• Some light will leave the water,
• Some light will reflect back downwards at an equal angle.
Total Internal Reflection
• At a certain angle...
• Light doesn’t go through the surface of the water anymore!
• Demo...
Critical Angle: Θc
• Occurs when:
• ni > nt and Θi > Θc
“Occurs when:ni > nt and Θi > Θc”
What does this mean?
• ni > nt : • Θi > Θc :
Finding the critical angle:• Sound familiar:
• ni sinΘi = nr sinΘr
• When Θr = 90, TIR occurs.
• sin(90) = ___?• So...........
• sinΘc = nr/ni
• (Does everybody know where the sin-1 button is on their calculators?)
• Know of any technology that uses this principle???
Total Internal Reflection HW
• Read p. 403-405
• Do p. 410 # 10, 11, 16, 22, 23, 50-53