Problem P. 4001. (September 2007)
P. 4001. Two objects are placed to the principal axis of a thin converging lens. One is 20 cm from the lens and the other is on the other side of the lens at a distance of 40 cm from the lens. The images of both objects are in the same plane. What is the focal length of the lens?
Deadline expired on 11 October 2007.
|126 students sent a solution.|
|4 points:||106 students.|
|3 points:||5 students.|
|2 points:||5 students.|
|1 point:||4 students.|
|0 point:||3 students.|
|Unfair, not evaluated:||3 solutions.|