A converging lens is used to project a 250 mm image of a square slide onto a screen 1000 mm away. the focal length of the lens is 200 mm. by means of scale drawing, determine---(a) the distance of the slide from the lens----(b) the size of the slide???

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Answer 1 · 2016-06-30T17:25:08

(a)Distance of the slide from lens = 250 mm

(b) The size of the slide = 62.5 mm

self drawn

Given

We are to find out

Calculation

Lens formula

#color(blue)(1/v-1/u=1/f)#

Plugging the values

#=>1/1000-1/u=1/200#

#=>1/u=1/1000-1/200=(1-5)/1000=-1/250#

#color(red)(=>u=-250mm)#

#color(green)("-ve sign means real object")#

Now magnification (m)

#m = s_i/s_o=v/u#

#=>250/s_o=1000/250=4#

#color(red)(=>s_o=250/4=62.5mm)#

The distance of the slide from lens (u)=250mm.

The size of the slide =62.5mm