Hello everyone, today our professor did this hw problem for us, just different numbers. This is the question: You produce an image of the Sun on a screen, using a thin lens whose focal length is 20.6 cm. What is the diameter of the image? (The mean radius of the Sun is 6.96x10^8 m and its mean distance from Earth is 1.50x10^11 m.) Okay here is my work, i'm using the formula: 1/i + 1/o = 1/f i = image distance o = object distance; f = focal length. I said: f = .206m sove for i http://img122.imageshack.us/img122/3278/lastscan9gt.jpg [Broken] I submitted .95584mm as my answer but was wrong! I did it just the professor, he does make mistakes alot when trying to help us (6 students) with homework any ideas?