Reflection
What is the law of reflection?
incident angle=reflected angle
How is the index of refraction defined? ex: how can we calculate it?
n=c/v (ratio of speed of light in a vacuum to speed of light in the medium)
A ray enters glass from air at 30 degrees. What angle does it leave the glass back to air?
30 degrees
The angle of a light ray is always measured from what reference angle?
90 degrees from the surface (normal)
If the reflected angle is 30 degrees from the normal, what was the incident angle?
30 degrees
Why does light bend when it goes into a different medium?
The speed of the light waves changes
A light ray enters glass (n = 1.50) from air at 40°
25.4 degrees
Light travels from oil (n = 1.47) into air. What is the critical angle?
42.9 degrees
Specular=reflects off an even surface Diffuse=reflects off an uneven surface (light scatters)
A ray in glass strikes the boundary at exactly the critical angle. What happens?
It reflects along the boundary line
Light is incident from air on glass (1.50) at 42 degrees, it then goes into water (1.33) and back to glass. What is the angle when it returns to the glass?
26.5 degrees
What is the phenomenon that causes rainbows?
Dispersion
A ray hits a mirror at 35°. What is the angle between the incident and reflected rays?
70 degrees
A light ray goes from air into an unknown material and bends away from the normal. What must be true?
bends away from normal
A ray enters glass (n = 1.50) from air at 45°, travels through, and exits into air.
What is the angle between the incident ray and the emerging ray?
0 degrees
Light travels through 1.2 m of glass (n = 1.50).How long does it take?
6.0 × 10⁻⁹ s
2 mirrors form a 120 degree angle. If a light ray enters at 65 degrees, what angle does the ray hit the second mirror?
55 degrees
What is the speed of light in a material with refractive index 1.80
1.7E8
Light travels through 0.80 m of water (n = 1.33) and then 1.20 m of glass (n = 1.50)
9.55E-9
A light ray in a lake strikes the surface at 60°.
Will it undergo total internal reflection?
yes