Recent content by Fabon

Well that's a great explanation - thank you! Concerning your explanation, the field would point in a direction as I drew on the picture?

Yes! The force and the acceleration is constant. Maybe I can use the right-hand-rule? Or just for magnetic fields?

Homework Statement I'm right now trying to solve a question concerning the direction of an electron in an electric field. There is the picture I added given and you know that there is a homogeneous electric field. The blue line represents the movement of an electron (there is no movements up...

Well, so the ruler measures the diameter D of the light-circles on the picture. So does this mean that the diameter of the lens is D as well? I think I'm confused...

according to the diameter of the lens? Does the size of the image of the ruler depends on the distance to the lens? That irritates me, since we don't know the distance.

a virtual image? Second try! This time I improved my drawing. :D

Is it possible to place the screen on the position (behind the lens) where I wrote ruler?

I hope I got the situation. Sorry for my terrible drawing (as I noted on the picture, the rays coming of the lamp are supposed to be parallel).

That's already a nice aspect for me to understand the situation - thank you. But how will this knowledge help me to find the diameter?

Since they are nearly parallel, they would focus (near to or) in the focal point. After meeting, the rays would diverge.

Mhh, maybe it is not even possible to project such an object on the other side, since the focal ray would have to point upwards.

Well, the principle ray and the focal ray would occur to be nearly parallel, since they are so far away, and the rays would meet very close after passing the lens.

By saying ray diagrams I mean something like this http://facstaff.gpc.edu/~pgore/PhysicalScience/ray_diagram_sample.jpg but I have no idea, weather this will help me out. And the basic laws I know are these two http://www.oocities.org/rjwarren_stm/Physics_Notes/TLF.gifConcerning your question...

Hey everybody, I'm right now trying to solve a question I found in a German physics competition 2006 concerning the diameter of a thin camera lens. I'm not able to find a solution, since there is basically nothing given. Here the task (I underlined phrases which might be important): A ruler...