- #1
Saturnfirefly
- 11
- 0
Homework Statement
1. When light travels from a material to air, total reflection occurs beyond 54 degrees. Calculate the index of refraction.
2. A converging lens has a focal length of 20 cm. When an object is placed at a certain disctance from the lens, a virtual image is created. How far from the lens is the object placed if the height of the image is 4 times greater than the object?
Homework Equations
1. sinC= n2/n1
2. ?
The Attempt at a Solution
1. I can use the equation, but I don't know how to calculate(?) the critical angle. I don't think any calculating is neccesary. The critical angle should be 45 (I'm not totaly sure) degrees, and my question is why?
2. I know that you have to place the object within the focal point to get a virtual image using a converging lens. And that tells us that the answer should be -something. But I don't know how to solve the equation... anyone that can by detail show me how to solve it? Answer should be di = -60
Last edited: