What is the Role of J in Dynamic Ohm's Law?

This can also be related to the equation \int_V{ J dV} = \frac{dp}{dt} = \frac{d\int_{V'}{r' \rho{r'} dV'}}{dt}.
  • #1
berra
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Homework Statement


What is J in Ohms law in dynamics?

Homework Equations


Ampères law:
[tex]\nabla \times H = J_f + \partial_t D = J_f + \partial_t ( \epsilon_0 E + P) [/tex]
[tex]\nabla \times H = \nabla \times (\mu_0^{-1} B - M) = \nabla \times (\mu_0^{-1} B) - \nabla \times (M) = \nabla \times (\mu_0^{-1} B) - J_m [/tex]
[tex]\nabla \times (\mu_0^{-1} B) = J_m + J_f + \partial_t ( \epsilon_0 E + P)[/tex]
Ohms law (statics?):
[tex]\sigma E = J[/tex]
Relation between J and p (magnetostatics ?):
[tex]\int_V{ J dV} = \frac{dp}{dt} = \frac{d\int_{V'}{r' \rho{r'} dV'}}{dt} [/tex]

The Attempt at a Solution


Is [itex]J = J_m + J_f + \partial_t (P)[/itex] ?
 
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  • #2
I think J in Ohms law in dynamics is the same as the J in Ampères law in statics, which is equal to J_m + J_f + \partial_t (P).
 

FAQ: What is the Role of J in Dynamic Ohm's Law?

What is current density?

Current density is a measure of the amount of electric current flowing through a given area. It is typically denoted by the symbol J and is expressed in units of amperes per square meter (A/m2).

What is Ohm's law?

Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. In other words, the current (I) is equal to the voltage (V) divided by the resistance (R): I = V/R.

How is current density related to Ohm's law?

Current density is directly proportional to the electric field strength and inversely proportional to the electrical resistivity of the material, according to Ohm's law. This means that as the electric field strength increases, the current density also increases, but as the electrical resistivity increases, the current density decreases.

What is the unit of measurement for current density?

The unit of measurement for current density is amperes per square meter (A/m2). However, it is also sometimes expressed in other units such as amperes per square centimeter (A/cm2) or amperes per square millimeter (A/mm2).

How is current density calculated?

Current density can be calculated by dividing the current (I) by the cross-sectional area (A) of the conductor. This can be expressed mathematically as J = I/A. Alternatively, if the current density and the cross-sectional area are known, the current can be calculated by multiplying them together: I = J x A.

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