Recent content by robb_

So can you quantify how the flux changes?

A changing flux induces an emf around the circuit. Find out the relationship between this emf and other physical quantities.

So, did you draw a ray trace of this system? I don't think that is needed but a good idea none the less. Use the lens equation twice, noting that you do not know the separation by including appropriate variables in your equations. hope that helps.

seems okay to me but I am tired. :bugeye:

The electric field equation you state is for a point charge. ( and other limited cases)

Draw a picture and note that the distance between the lenses is an unknown, a variable.

I haven't checked the maths but if Fnet is zero the rest is okay.

Free body diagrams area great tool but you must know what forces act on the object. To do that, just run through the list of forces you studied. Look for things pushing or pulling on the object. Remember that there are strange forces such as gravity that act as "invisible pushers." A normal...

Now if you are trying to decide which string to use, how could you decide? That is not what I was getting at. You need to consider the tensions here, but what is providing that normal force you have??

I think you have over simplified slightly. The first equation looks okay. That will give you the image distance, that is the distance from the first lens to the first image. You do not know the distance between the lenses, so you do not know how far this image is from the second lens. Understand?

Now wait, you have Fg in your equation, the force on the bird due to gravity, then Fn from the string, then two more forces that look like tension. I think you have "double counted."

I understand your point. I am not sure of the level of the problem as given and what type of answer to give. If the OP has studied said law, it seems the most reasonable. *edit again* Sorry for the double post here. I am having some troubles today it seems. Well it is a holiday of sorts. : )

If you state that, then I must ask what is providing the tension forces you state?

Have you studied heat transfer equations?

I understand your point. I am not sure of the level of the problem as given and what type of answer to give. If the OP has studied said law, it seems the most reasonable.