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a lens of focal length 20cm is used to produce a ten times magnified image of a film slide on a screen. How far must the slide be placed from the lens ?

a lens of focal length 20cm is used to produce a ten times magnified image of a film slide on a screen. How far must the slide be placed from the lens ?

Grade:12

2 Answers

Chris Chan
33 Points
11 years ago

 use the formula of linear magnification-

      m=f/u-f  = 20/10-20= -2cm

Shobhit kaushik SIR
15 Points
4 years ago
U= ?       f= +20 cm       v= ?  m= 10 ( image is real and inverted)
Magnification = v/u 
    - 10 = v/u now v= -10u
      1/f= 1/v - 1/u 
    1/20= 1/-10u - (1/-u) now u =-22 cm
    Image distance v = -10u = -10×(-22) = 220 cm
 
 
 

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