5. a copper wire of length 6.3 m has a potential difference of 1.2 v applied across its ends. what is the current density? can you calculate the e field in the wire?

The current density is 2.15 × 10⁶ A/m²The amount of current flowing per cross-sectional area is called current density and is expressed in amperes per square meter. The more current that flows through a conductor, the higher the current density.Current density is the amount of current that flows per unit cross-sectional area of ​​a material. Therefore, the SI unit of current density must be Ampere/m2. Current density is defined as the ratio of current flowing through a conductor to the cross-sectional area of ​​the conductor perpendicular to the direction of current flow. The relationship between current density J and drift velocity vd is given by J=n e vd.current i = V/r = V /ρL/A               = πVd²/4ρL = π(1.2 V) (0.00400 in) (2.54 × 10⁻²)/4(1.69 × 10 Ωm)33 m = 1.74 AThe current density J =i/A                                   = 4i/πd²                                  = 4 (1.74)/ π(0.0400 in)(2.54× 10⁻² m)²                                  = 2.15 × 10⁶ A/m²Learn more about current density here:-https://brainly.com/question/24704849#SPJ4