Comparing Electric Potential of +Q at A & B

physicsstar26
Messages
7
Reaction score
0

Homework Statement


Two test charges are brought separately into the vicinity of charge +Q. First the test charge +q is brought to a point A, a distance r from +Q. Next, +q is removed and a test charge +3q is broguht to a point B, a distance 2r from +Q. Compared with the electric potential of +Q at point A, that of +Q at B is how much that of A. The choices are tiwce that of A, 1.5 times, the same as A, half of A, or 3/4 that of A



Homework Equations


I was using the equation kq/r for electric potential and plugging in numbers but I'm unsure what to else to do.


The Attempt at a Solution

 
Physics news on Phys.org
physicsstar26 said:

Homework Statement


Two test charges are brought separately into the vicinity of charge +Q. First the test charge +q is brought to a point A, a distance r from +Q. Next, +q is removed and a test charge +3q is broguht to a point B, a distance 2r from +Q. Compared with the electric potential of +Q at point A, that of +Q at B is how much that of A. The choices are tiwce that of A, 1.5 times, the same as A, half of A, or 3/4 that of A



Homework Equations


I was using the equation kq/r for electric potential and plugging in numbers but I'm unsure what to else to do.


OK, this is a sneaky one. Be careful about the fact that they are asking about the electric *potential* of the +Q charge at points A and B. You have the correct formula for the potential, so what should you write for each part of the comparison?
 
##|\Psi|^2=\frac{1}{\sqrt{\pi b^2}}\exp(\frac{-(x-x_0)^2}{b^2}).## ##\braket{x}=\frac{1}{\sqrt{\pi b^2}}\int_{-\infty}^{\infty}dx\,x\exp(-\frac{(x-x_0)^2}{b^2}).## ##y=x-x_0 \quad x=y+x_0 \quad dy=dx.## The boundaries remain infinite, I believe. ##\frac{1}{\sqrt{\pi b^2}}\int_{-\infty}^{\infty}dy(y+x_0)\exp(\frac{-y^2}{b^2}).## ##\frac{2}{\sqrt{\pi b^2}}\int_0^{\infty}dy\,y\exp(\frac{-y^2}{b^2})+\frac{2x_0}{\sqrt{\pi b^2}}\int_0^{\infty}dy\,\exp(-\frac{y^2}{b^2}).## I then resolved the two...
It's given a gas of particles all identical which has T fixed and spin S. Let's ##g(\epsilon)## the density of orbital states and ##g(\epsilon) = g_0## for ##\forall \epsilon \in [\epsilon_0, \epsilon_1]##, zero otherwise. How to compute the number of accessible quantum states of one particle? This is my attempt, and I suspect that is not good. Let S=0 and then bosons in a system. Simply, if we have the density of orbitals we have to integrate ##g(\epsilon)## and we have...
Back
Top