Physics

A spherical shell has inner radius R-in and outer radius R-out. The shell contains total charge Q, uniformly distributed. The interior of the shell is empty of charge and matter. Find the magnitude of the electric field within the shell, R-in <= r <= R-out. Basically find the E-f within the sphere. I don't really think I understand it. The charge lies all on the exterior, so the interior surface must have -Q. I have tried several different answers, but they say that it depends on R-in and, I assume R-out. I know its a Gauss problem and E = Q/A*e-0, but I am having trouble finding the Q. Do I find the volume density of the big sphere and multiply it…

I wasn't sure where this question should go, so I'm posting it here. What's a good example of a particle that fissions to produce two particles with opposite spins?

Hi, I would like to know why compound microscopes magnify the intermediate image to create the virtual image, instead of directly magnifying the target object. Is it something to do with the image being inverted, flipped, inside out or just distorted? I've attached a very basic essay which anyone interested in replying can review, the passage in question reads as "The second lens is basically just a magnifier, however instead of directly magnifying the original object, the lens magnifies the intermediate image and creates what can be described as an enlarged, inverted ‘imaginary image’ which is then projected into the eye which in turn, forms a real image." DI-Es…

Is there any specific object/equipment that you can use to measure the dielectric breakdown of air? Or if there's no such equipment, is there any way to fix together some lab apparatus to construct something which can do so?

I am thinking about giving a short presentation to an amateur astronomy association. They have asked what I do at work, I don't think I can explain much about that but I was thinking about giving an introduction to general relativity. For those that know something about me, will know that I study mathematical physics using geometry and general relativity, I though could be a reasonable way of introducing some "geometric concepts" to astronomers. I have a basic plan in my mind, but I will work on it before I give the talk. As my audience has little mathematical sophistication, I was planning to present most of the ideas very intuitively and very pictorially, sacrifi…

Well, I dont know how many of you have seen this site: http://www.u-starvin.com/micromaniac/ They microwave alot of stuff - I understand it all, except the christmas lights. how do they light up?

I understand that e.g. pollen grains reflect the movement of the molecules in the e.g. water around them Perhaps the induced movement of the pollen indicates that they have absorbed some energy and this generates some heat through friction, returning it to the system as the molecules lose heat to the pollen This, like the rotation of planets, looks like 'perpetual motion', so may I ask what is really going on?

What's the scientific word for this? Like... not comparable in a sense.

Hi, Just wondering if there is anything that you can paint or stick onto the 'attracting' part of a magnet to stop it being so magnetic? thanks

Bullet proof glases contain polycarbonate layer sandwithed between two glass layers. How polycarbonate layers prevent bullets? Does it totally prevent piercing of glass? Is it directional i.e is from one side only?

First, whats it called when your brakes fail from too much heat? Second, how does this happen? Why does excessive heat cause the brakes to fail to put enough pressure on the disks? thanks

In one book I read about boiling water in a paper cup. Actually I tried heating a water in a paper cup till it becomes hot. Paper did not burn. I am interested to know the principle behind it. Similarly one more article in the book says If you roll a pencil with paper and heat it in a flame paper does not burn ( This I have not tried)

When there is an electrical current running through copper what temperature or temperatures does the copper wire strand reach?

What is involved in making a week source of microwaves, something small that isn't attached to the steel box you'd normally expect a microwave to come with and with less power that runs of batteries but that produces micowave frequency electromagnetic waves?

If an ice cube is dropped in a glass of water what happens to the level of water after melting of ice? increase, decrease or remain same?

I know that when you rub a balloon against your hair or a piece of wool that electrons are stripped from them and go across to the balloon, giving the balloon a negative charge. And you can rub a glass rod with a piece of silk and the rod loses electrons, making it positive. But what I don't understand is why the electrons move across to the different materials. What property of the material determines whether it will lose or gain electrons? Any help would be great.

Kind of a very basic question, but I am not basically a physicist. A bucket with two holes on its sides is filled with water. If the bucket is allowed to free fall from a tower, will the water fall through the holes OR the water will not fall OR the water will spill from the top of the bucket ????

I don't get how an electric current can go through a conductor faster than the individual electrons flowing through. How can the electrons make a current go across a conductor at the speed of light when the electrons themselves aren't moving across the conductor at that speed?

Does anyone know exactly how an inductance transmitter works? Any input would help .. Thanks

Why warm water freezing faster than cold water? Can somebody explain this?

Hi, I am after some advice from you guys, it would be much appreciated.... I am looking for your recommendation on the best material that when placed out in the sun all day would have heated up very well and then continue to hold that heat with not much loss (or very slowly) all through the night, so that are small area could be heated Any ideas? I have been looking at cast iron which seems good but to be honest it's one of the first I came across! So I thought i'd approach you guys for more expert advice, You suggestions would be much appreciated and thanks in advance. oh, a lightweight material would also be an advantage, thanks

I have a sweater that is 40% acrylic and 60% polyester. It looks as if it was knitted, i.e. it has little tiny holes in between the threads (see pictures). I'm shortsighted, and when I take off my glasses and put the sweater in front of the eyes, I can see much more clearly than I can without glasses. It's not as clear as when I do have my glasses, and the threads get in the way, but there is a marked difference. I'm guessing light gets diverged like going through a corrective lens, but all it does here is pass through small, physical holes. Why does my vision get clearer when I wear my sweater in front of my eyes?

Electromagnetic radiation that is ionizing and is able to bring about changes in atoms is called ionizing radiation. Correct? So my question then is, can any portion of the Electromagnetic Spectrum be ionizing? Can you for instance, have ionizing blue light? Or do certain portions of the electromagnetic Spectrum such as visible light only come in non-ionizing packages?

I'm attempting to understand their difference, and their relationship. The Electomagnetic Specturm ranges from Gamma Waves to Long Wave Radio waves, and everything in between. Electromagnets and other kinds of electronic equipment and power lines give off electromagentic fields. My question is, are the electromagnetic fields emanating from electronic equipment and other electromagnetic sources, part of the Electromagnetic Specturm? If so, what portion are they in? If not, what is their relationship?

Hi all. If a lenght of empty (with atmospheric air) aquarium hose is plugged with beads of silicone sealant at the ends; and placed inside a plain household water pipe... When the water pipe is placed in operation, at say 3 Atm water pressure, the hose inside will contract/deform due to the pressure. Would the plugs at the ends tend to burst outwards or inwards or will not be affected at all ? Just want to confirm am not missing something here... Miguel