Current Density: E,D,pv and Jz @ z=0 & z=.1m

Click For Summary
SUMMARY

The discussion focuses on calculating electric field (E), electric displacement field (D), and volume charge density (pv) as functions of z in a potential defined by V=90z^(4/3) at z=0. The derived expressions are E=120z^(1/3)az V/m, D=1.062z^(1/3)az nC/m², and pv=0.354/z^(2/3) nC/m³. Additionally, the current density (Jz) is questioned, with the participant unsure if it should be calculated using J=pv*v, given the velocity component vx=5x10^6*z^(2/3) m/s. The confusion arises from the lack of a defined z-component for velocity.

PREREQUISITES
  • Understanding of electrostatics and Maxwell's equations
  • Familiarity with vector calculus, particularly divergence
  • Knowledge of charge density and current density concepts
  • Basic proficiency in solving differential equations related to electric fields
NEXT STEPS
  • Study the derivation of electric fields from potentials in electrostatics
  • Learn about the relationship between charge density and current density in electromagnetic theory
  • Explore vector calculus applications in physics, focusing on divergence and curl
  • Investigate the implications of velocity components in charge distributions
USEFUL FOR

Students and professionals in electrical engineering, physicists working with electromagnetic fields, and anyone studying charge dynamics in electrostatics.

oggrol
Messages
3
Reaction score
0
Let E=Eo (err...free space, not sure how to represent the symbols)
V=90z^(4/3) in the region z=0(Potential)
a) Find expressions for E,D and pv (volume charge density) as functions of z

My work:
E=-div V=0+0)120z^(1/3)az=120z^(1/3)az V/m
D=Eo E=1.062z^(1/3)az nC/m^2
pv=div D=.354/z^(2/3) nC/m^3

b)If the velocity of the charge density is given as vx=5x10^6 *z^(2/3) m/s, find Jz (current density) at z=0 and z=.1m

My work:
Now this is where I am confused because J=pv*v (volume charge density*velocity vector). And the book only gives the x component of the velocity vector and asks for the z component of the current density. If you ask me, that means the z component of the current density is 0, but I have no way of checking my answer.

:confused:

Is this correct?
 
Last edited:
Physics news on Phys.org
Still not sure about part b of this one, and running into more problems with the stuff :cry:
 
Teacher posted solutions today...

had Jz=Pv*Vx ...

Still don't believe that though unless it was a misprint in the book or something ... doesn't make sense to me
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 17 ·
Replies
17
Views
3K
Replies
1
Views
2K
  • · Replies 26 ·
Replies
26
Views
4K
Replies
5
Views
5K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
12
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 11 ·
Replies
11
Views
4K