Question

Two converging lenses, the first with focal length 10.0 cm and the second with focal length 20.0 cm, are separated by 40.0 cm. An object, 3.00 cm in height, is placed 30.0 cm in front of the first lens. what is the height of the final image?

a) 12cm

b) 6.0cm

c) 1.5cm

d) 3.0cm

e) 24.0cm

Answer 1

Answer
Given 9 converging lens. fi=+10cm , f2=+90 cm Seperation = 40 cm Vem 10 - Object distances -30cm. For first lens ; image distance -- to temo to te to go 3 us 15cm from lens 1 Magnification 15 - hi= .5cm. 3o [Image heght] Now, object distance from lens I become 40-15-25 cm u= -95cm for lemas d, so image distance

ut the = t + s = ato t to us to shoot ; ve loom from lens 2 Magnification (Final) Height of image = I x Height of object Loo x 1,5 Final height = 6cm So option (b) is correct. 25