A slide projector has a converging lens whose focal length is 102.00 mm. (a) How
ID: 1380889 • Letter: A
Question
A slide projector has a converging lens whose focal length is 102.00 mm. (a) How far from the lens must the screen be located if a slide is placed 108 mm from the lens?m
(b) If the slide measures 21.0 mm A slide projector has a converging lens whose focal length is 102.00 mm. (a) How far from the lens must the screen be located if a slide is placed 108 mm from the lens?
m
(b) If the slide measures 21.0 mm (a) How far from the lens must the screen be located if a slide is placed 108 mm from the lens?
m
(b) If the slide measures 21.0 mm
Explanation / Answer
a) first use the thin lens formula
1/u + 1/v = 1/f
where u is distance fbetween lens and object
v is the distance between lens and image
f= +102 mm( positive for converging lens)
1/v = 1/f - 1/u
1/v = 1/102mm - 1/108mm = 0.0005446
v = 1/0.00034 = 1836mm .. .. .. image distance ?= 1.83 m
2) the image formed will be real
now magnification is given by
m=-v/u
=-(1836/108)
=-17
now;
image width = slide width x magnification=21 x17 mm=357mm
image height = slide height x magnification=37x17mm=629mm(inverted image will be formed,see the negative sign )