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The focal length of a converging lens is found to be 10 cm. How far should the lens be placed from an illuminated object to...

      

The focal length of a converging lens is found to be 10 cm. How far should the lens be placed from an illuminated object to obtain an image which is magnified five times on the screen?

  

Answers


Mutiso
f = + 10 cm m = v / u = 5 hence v = 5 u
Using the lens formula 1 / f = 1 / u + 1 / v => 1 /10 = 1 / u + 1 / 5 u (replacing v with 5 u) 1 / 10 = 6 / 5 u, hence 5 u = 60 giving u = 12 cm (the lens should be placed 12 cm from the illuminated object)
Mutiso answered the question on October 15, 2018 at 18:02


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