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Current density refers to the density of current flow in some conductor. It is denoted by the symbol J. In the field of electromagnetism, Current Density and its measurement is very important. It is the measure of the flow of electric charge in amperes per unit area of cross-section i.e. m².

## What is J in electrical conductivity?

As current density is given by **J=I/A** (Refer article of Current Density, Conductance and Electrical Conductivity) and resistivity is given by ρ=m/ne^{2}t.

## What is Q in electric current?

Electric current calculation

Q(t) is **the momentary electric charge in coulombs (C)**. t is the time in seconds (s). When the current is constant: I = ΔQ / Δt. I is the current in amps (A).

## Why current is scalar?

Electric current is a scalar quantity. … In the case of electric current, when two currents meet at a junction, **the resultant current of these will be an algebraic sum and not the vector sum**. Therefore, an electric current is a scalar quantity although it possesses magnitude and direction.

## What is current density equal to?

The SI unit of current is the ampère [A]. An ampère is a coulomb per second. The ampère is one of the seven base units of the International System of Units. The unaccented spelling ampere is also acceptable in written English.

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Summary.

J, J = | current density [A/m] as a vector or its scalar magnitude^{2} |
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A = | area [m^{2}] |

For an amazingly wide range of materials, an empirical rule called Ohm’s law gives the following relation between current density and applied electric field: **J = σ E** . In other words, the current density is directly proportional to the electric field.

## What is sigma conductor?

**Electrical conductivity or specific conductance** is the reciprocal of electrical resistivity. It represents a material’s ability to conduct electric current. It is commonly signified by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) and γ (gamma) are sometimes used.