Question

A slide projector uses a thin lens with a focal length 132 mm to project a clear image on a screen located 10.5 m from the lens. Calculate the distance the slide is from the lens and the magnification obtained 513 mm, m = -20.5 O 134 mm, m = -78.4 154 mm, m =-54.9 513 mm, m = 20.5 O 585 mm, m = -17.9

Answer 1

Answer

Given

Focal length = 132 mm = 0.132 m

Image distance v = 10.5 m

Slide distance = u

Using lens formula 1/v – 1/u = 1/f

1/u = 1/v – 1/f

U = vf/ ( f- v) = (10.5 x 0.132)/ 0.132- 10.5 = 1.39 / -10.37 = 0.134 m = 134 mm

Magnification = v/u = 10.5 /-0.134 = - 78.35 = -78.4

Second option is the correct answer