A 4.0 cm tall candle flame is 2.0 m from a wall.

) 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

  • 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

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