) A 4.0 cm tall candle flame is 2.0 m from a wall. You happen to have a lens with a
focal length of 32 cm. How many places can you put the lens to form a well-focused
image of the candle flame on the wall? For each location, what are the height and
orientation of the image
1 Answer
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s = 200 - s'
1/s + 1/s' = 1/f
1/(200 - s') + 1/s' = 1/32
s' = 40 cm
or
s' = 160 cm
for s' = 40 cm ⇒ s = 160 cm
h'/h = s'/s
h'/4 = 40/160
h' = 1 cm
for s' = 160 cm ⇒ s = 40 cm
h'/h = s'/s
h'/4 = 160/40
h' = 16 cm
