
#1
Aug308, 03:10 PM

P: 25

1. The problem statement, all variables and given/known data
An object is 18cm in front of a diverging lens that has a focal length of 12cm. How far in front of the lens should the object be placed so that the size of its image is reduced by a factor of 2.0? 2. Relevant equations 1/do + 1/di = 1/f m= di/do 3. The attempt at a solution i keep solving and getting 36 using those equations, but the answer says its 48 ...i donno how to get 48 1/18 + 1/di = 1/12 di=7.2 m= 7.2/18 m=.4 1/2m=0.2 .2= 7.2/do do=36 



#2
Aug308, 03:16 PM

HW Helper
P: 2,688

Can you show your calculations, please? I can't find your mistake if I can't see your work.




#3
Aug308, 03:19 PM

P: 25

k i edited it




#4
Aug308, 03:30 PM

HW Helper
P: 2,688

lenses question
Hmmm. I am also getting 36 as my answer. I know this is a stupid question, but are you sure your numbers are correct? It doesn't hurt to check. Also where are you getting the answer from?




#5
Aug308, 03:38 PM

P: 25

physics textbook




#6
Aug308, 08:58 PM

P: 25

bump




#7
Aug408, 06:46 AM

Sci Advisor
HW Helper
Thanks
P: 26,167

Try using 8cm instead of 18cm. 



#8
Aug408, 11:06 PM

HW Helper
P: 2,250

Hi physicsdawg,
[tex] 0.2 =  di/do [/tex] and you need to find do. Do you see how to find it? 


Register to reply 
Related Discussions  
Lenses Question  Introductory Physics Homework  0  
Lenses Question help!  Introductory Physics Homework  2  
Quick Question about lenses/refraction  Introductory Physics Homework  1  
question about sound and lenses  General Physics  0  
Question about Convex lenses  General Physics  6 