How Far Are You From This Lens?

[binhnguyent9]

Homework Statement

You are standing in front of a lens that projects an image of you onto a wall 2.80 {\rm m} on the other side of the lens. This image is three times your height.
How far are you from the lens?
Is your image erect or inverted?
What is the focal length of the lens?
Is the lens converging or diverging?

Homework Equations

none

The Attempt at a Solution

none

thanks a lot for your help

 

[rl.bhat]

Which lens produces real magnified image?
What is the realtion between the objectg distsnce, image distance and magnification?

 

[binhnguyent9]

well the convex len can produce a real image, and m=-image distance/ object distance. i have try everything, and i don't know why it keep tell me i am wrong, if you don't mind can you do one of the part, then i can check it? thanks a lot for your help

 

[rl.bhat]

Image distance is given. Magnification is given. Find the object distance.
Use the formula
1/do + 1/di = 1/f
For real image di is +ve.
And for virtual image di is -ve.

 

[binhnguyent9]

oh ok, thanks a lot. i think i misread the question first. thanks so much for your help