Cavity Definition and 260 Threads

In the context of properties of conductor & 1st Uniqueness theorem, Griffiths proves that field inside a cavity( empty of charge) within a conductor is 0. Is the result same if we place a +q & a -q (so that Q(enc)=0) suspended in air inside the cavity?

A positive charge Q = 1400.00 C is uniformly distributed over the volume of a sphere of radius R = 10.00 m. Suppose a spherical cavity of radius R/2 is cut out of the solid sphere, the center of the cavity being a distance R/2 from the center of the original solid sphere (see figure). The...

I got a HeNe tube with a constant size which has a concave mirror at one end. Im changing the distance of the other mirror from the tube.. now, i know some distances arent stable, but appart from the Heaviside function, is there any other change in the beam's strength? the only thing that...

Does an electric field exist in the center of a cavity inside a sphere? Can I just apply Gauss's law and say that because no charge is enclosed, the electric field is zero? If not, why can Gauss's law not be applied? Thanks, positron

I am thinking over this, there are two spherical cavities in the interior of a neutral conducting sphere.the cavities have point charges qA and qB respectively at their centres. What will happen when we bring a third charge near the sphere...

This might be a bit to specalised for some of you, but i am trying to calculate the number of modes that light can propegate in a material. The question is as follows Consider a cavity that is a cube with the side length a = 1mm filled with water (refractive index(n) 1.33). Calculate the...

Why is the density of standing waves in a cavity G(f)df=((8*pi*f^2)/(c^3))*df? Also that formula looks weird... doesn't look like it has anything to do with density...

I tried to calculate the casimir force. I need to know if the way I doing it is correct. So I note some steps: 1. I calculate the energy in the space without the plates 2. I calculate the energy between the two plates And then I speculated. I thougt of taking the difference of one and two...

I have been working on an experiment that uses double exposure holography to determine sub-micrometer displacements. [see attached picture for details] It turns out that the optical path lengths LRP and LOP do not have to be exactly but roughly equal for the light if you want the light from R...

I have a question regarding fluids A small sculpture made of gold (density of gold = 19280 kg/m^3) is believed to have a secret central cavity. The weight of the sculpture in air is 25.76 N. When submerged in water, the weight is 23.86 N. What is the volume of the secret cavity. (Density of...