- #1
foolISH
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Optics, lens problem pleaase help :)
1. Two converging lenses, the first with focal length 40 cm and the second with focal length 33 1/3 cm, are separated by 10.0 cm. An object of height 6.0 cm is placed 20.0 cm in front of the first lens. What are the size and orientation of the final image?
A. 6.0 cm, upright
B. 6.0 cm, inverted
C. 24.0 cm, upright
D. 24.0 cm, inverted
E. 1.5 cm, inverted
this is my work :
f1 = 40 cm
ho = 6 cm
do = 20 cm
1/f = 1/di + 1/do
1/40 = 1/di + 1/20
di = -40
f2 = 33.3 cm
do = 10 cm
1/f = 1/di + 1/do
1/33.3 = 1/di + 1/10
di = -14.29
m = -di / do
m = 14.29 / 10
m = 1.429
m = hi / ho
1.429 = hi / 6 cm
hi = 8.574
clearly, that's not one of the given options :(
can someone pleease tell me wat I am doing wrong ?
thnxx
1. Two converging lenses, the first with focal length 40 cm and the second with focal length 33 1/3 cm, are separated by 10.0 cm. An object of height 6.0 cm is placed 20.0 cm in front of the first lens. What are the size and orientation of the final image?
A. 6.0 cm, upright
B. 6.0 cm, inverted
C. 24.0 cm, upright
D. 24.0 cm, inverted
E. 1.5 cm, inverted
this is my work :
f1 = 40 cm
ho = 6 cm
do = 20 cm
1/f = 1/di + 1/do
1/40 = 1/di + 1/20
di = -40
f2 = 33.3 cm
do = 10 cm
1/f = 1/di + 1/do
1/33.3 = 1/di + 1/10
di = -14.29
m = -di / do
m = 14.29 / 10
m = 1.429
m = hi / ho
1.429 = hi / 6 cm
hi = 8.574
clearly, that's not one of the given options :(
can someone pleease tell me wat I am doing wrong ?
thnxx