Magyar Information Contest Journal Articles

# Problem P. 4142. (February 2009)

P. 4142. An object is at a distance of d from a screen. The convex lens, placed between them, forms the sharp image of the object at the screen at two different positions, the distance between these positions is s.

a) Find the focal length, f, of the lens.

b) Suppose that d is known very precisely. When will the uncertainty in the measurement of s cause a greater error in the calculation of f if the value of s is greater or if it is smaller?

(4 pont)

Deadline expired on 11 March 2009.

### Statistics:

 91 students sent a solution. 4 points: 62 students. 3 points: 7 students. 2 points: 13 students. 1 point: 4 students. 0 point: 3 students. Unfair, not evaluated: 2 solutions.

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