1) You are asked for a ray diagram and the angle of reflection. 2) You are given the angle of incidence. 3) The law of reflection states the angle of reflection equals the angle of incidence. 4) The angle of reflection is 30°.
1) You are asked for the angle of refraction. 2) You are told the ray goes from air into water at 30 degrees. 3) Snell’s law: ni sin(θi) = nr sin(θr) ni = 1.00 (air), nr = 1.33 (water) 4) Apply Snell’s law to find θr. 1.00sin(30°) = 1.33 sin(θr) sin(θr) = 0.5 ÷ 1.33 = 0.376 Use the inverse sine function to find the angle that has a sine of 0.376. θr = sin-1(0.376) = 22°
The angle at which light begins reflecting back into a refractive material is called the critical angle, and it depends on the index of refraction. The critical angle for water is about 49 degrees.
A converging lens bends an incident light ray parallel to the optical axis toward the focal point. A diverging lens bends an incident light ray parallel to the axis outward, away from the focal point
1) You are asked for image distance. 2) You are given the focal length and object distance. 3) The thin lens formula applies: 1/di = 1/f — 1/do 4) Solve for di 1/di = 1/4 — 1/6 1/di = 3/12 — 2/12 = 1/12 di = 12 cm The image forms 12 cm to the right of the lens.