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KLscilevothma

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**physics contest-- question 3**

a) Complete the drawing below to show where the image of the object formed by the lens is

b) Use the drawing you have cpmplected, prove that 1/s + 1/s' = 1/f/

Here s is the distance bewteen the object and the lens, s' is the distance between the image and the lens, and f is the distance bwteen either of the focal points F and the lens.

c) Prove that the image magnification is M = s'/s

Part a, c : no problem

How do you do part b ?

Here's my answer.

After completing part a, my measuring the picture i drew, I got

s=5.9 cm

s'=6.1 cm

f =3 cm

1/s + 1/s' = 0.333

1/f = 0.333

QED (At least I can amuse the markers )