Practice Test Three, Physics 122
1) The intensity of light is 5mW/m2. What is the maximum electric field? _______
I=Emax
2
2μ0c
2) Light coming from material “A” with an index of refraction of 2.5 goes into a second
material, “B” (n =1.5) at an angle of 25º.
What angle is the light reflected within the material A? __________
What angle is the light transmitted into the material B? ____________
For light in material “A” going to material “B”, what is the critical angle? __________
3) While looking through a lens, objects that are close appear larger, but farther away.
What type of lens is this? ___________
4) Calculate the location, type and magnification of the image and draw a ray diagram
showing how the image is formed for the following situations:
a) A divergent lens with a focal length of -20 cm has an object 30 cm away from the
lens.
b) A convergent lens with a focal length of 20 cm has an object 15 cm away from the
lens.
5) In air material “C” has a critical angle of 65º.
What is the index of refraction for this material “C”? _____________________
What is the speed of light in the material “C”? ________________
