How Far Are You From This Lens?

  • Thread starter Thread starter binhnguyent9
  • Start date Start date
  • Tags Tags
    Lens
AI Thread Summary
The discussion revolves around a physics problem involving a lens that projects a magnified image of a person onto a wall. The image is three times the height of the person, and participants are trying to determine the object distance from the lens, the nature of the image (erect or inverted), and the focal length of the lens. It is clarified that a convex lens can produce a real image, and the magnification formula relates image distance and object distance. Participants emphasize the importance of correctly interpreting the problem and applying the lens formula to find the solution. The conversation highlights the collaborative effort to understand the concepts of optics and lens behavior.
binhnguyent9
Messages
6
Reaction score
0

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
 
Physics news on Phys.org


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


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
 


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.
 


oh ok, thanks a lot. i think i misread the question first. thanks so much for your help
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...

Similar threads

Replies
5
Views
1K
Replies
2
Views
1K
Replies
5
Views
2K
Replies
7
Views
3K
Replies
5
Views
2K
Replies
13
Views
2K
Replies
3
Views
3K
Replies
5
Views
2K
Back
Top