Reflection & Refraction of Light
• Reflection: specular (mirror) vs diffuse
angle of incidence = angle of reflection
• Refraction: c

v
n
where n 
Snell’s Law
n1sinq1 = n2sinq2
 o o
Total Internal Reflection
• Snell’s Law from glass to air:
n1sinq1 = n2sinq2
ngsinqcritical = nairsin90  nair
Group Problem
• If a beam of light takes 0.106 nanoseconds to
travel the distance L = 2.22 cm as shown
below, what is the angle of incidence that the
beam makes with the surface?2 cmL=2.22
cmθin2=1.5n1=1.0