Question

The current density at a point in a uniform
copper wire of area of cross-section 2.5 mm2
carrying a steady current of 1 nA is​

Answer 1

Answer:

the answer is 4

Explanation:

j (current density) = i (current)/ a (area)

1 nA= 10 A

j=10/2.5

j=4

Answer 2

Answer:

The current density at point of uniform copper wire is equal to 4×10⁻⁴Am².

Explanation:

Given: The current flows through the wire $I=nA=10^{-9}A$

The cross section area of wire $A=2.5mm^{2}=2.5*10^{-6}m^{2}$

The current density is equal to the ratio of current flows through the wire to the cross section area of the wire. It is denoted by J.

Current density $=\frac{current}{Area}$

    $J=\frac{I}{A}$

Current density, $J=\frac{10^{-9}A}{2.5*10^{-6}m^{2}}$

$J=0.4*10^{-3}Am^{-2}$

$J=4*10^{-4}Am^{-2}$