# Search results

1. ### Simple stats question

Homework Statement The problem goes like this. I have two parameters A and B, both which can only be true or false ( booleans ). Then, the only information I have is that for x events for which A is true, B is also true y times. My question then is, what is the most I can get out of these two...
2. ### Hypothesis testing, confidance leves, photon statistics

Homework Statement A source is supposed to emit photons with spin +/-1 independently at equal rate. a) after measuring 4 photons, all have spin +1; b) after measuring 100 photons, 60 have spin +1. at which confidence level can the hypothesis be rejected. Calculate for each of the...

Homework Statement A galaxy consist of a uniform slab of stars mixed with dust. The slab has thickness L, and optical depth \tau for a ray passing perpendicularly through the slab. assume the emmisivity of the stars \epsilon and the density of dust is constand throught the slab. Further assume...
4. ### Absolute color - magnitude diagram

Hello all, I am finding a distance to a cluster via Main Sequence fitting, and I don't know where to find an absolute color - magnitude diagram ( B-V, and V ). I can be from any star cluster, or sky region, as long as the magnitudes are absolute. I need the data tables, not just a pretty...
5. ### Self Inductance

Homework Statement Show that the self-inductance per unit length of a wire of radius R carrying a uniform current density inside, the current returning along the surface of the wire is μ0/8π. The Attempt at a Solution I thought that it might be simpler to calculate the self...
6. ### Conductors separated by interface

Homework Statement The Plane z=0 forms an interface between two conductors of conductivity σ1 and σ2 respectively. In the 1st conductor a steady current J1 flows and it makes an angle θ1 with the normal of the interface. Find the current in the 2nd conductor and the charge density on the...
7. ### Force on a sphere in a constant external electric field

Homework Statement An uncharged solid sphere is paced in a constant external electric field E0. What is the force on the sphere? Homework Equations The Attempt at a Solution I know ( already have found ) the electric potential and electric field around the sphere. Also worked out...
8. ### Elastic Collision in 2D between 2 Hard Spheres

Homework Statement By resolving the momentum equations parallel and perpendicular to the incident beam direction, show that α is related to the speed v2 of the recoiling particle by: cos α = m2*v2/(2μ*u1) where μ=m1m2/(m1+m2) Homework Equations See attachment for diagram...
9. ### Experiment with Electric field lines

Homework Statement Hello all. I need help or ideas on making an experiment in which I need to show the electric field lines. I think it should be somewhat similar the the experiment when you put lots of little metal pieces on a piece of paper and then you put a magnet below the paper, and...
10. ### QM step potential

Homework Statement A step potential is defined by: V(x) = 0 ( for for x <0 ) and V(x) = V0 ( for x >0 ). Hence the step occurs at the origin. Suggest a real physical situation, that might correspond to this idealized problem Homework Equations None needed. The Attempt at a Solution...
11. ### Induction and EMF

Homework Statement In a ring of radius R, there is current I flowing in the counterclockwise direction as viewed from above. A small ring of radius r is on a common axis and is a hight z above the current carrying ring, where z>>R. The small ring moves up with velocity v. Calculate the emf in...