Question

a) In a wire with a 2.81-mm2 cross-sectional area, 8.91 × 1020 electrons flow past any point during 2.61 s. What is the current in the wire?

b) Find the current density.

Answer 1

Given data Number of electron flows, n 8.91x10 Charge on electron, e = 1.6×10-19 C Time, t 2.61 s Cross sectional area of the wire, = 2.81 mm, = 2.81 × 10-6 m2 Write the expression to calculate the total charge pass through the point. Here, Q is the total charge pass through the point. Substitute the values in above equation. 0 8.91x102 x1.6x10-19 -142.56 C Write the expression to calculate the current in the wire. Here, I is the current in the wire. Substitute the values in above equation. 142.56 2.61 - 54.62 A Hence, the current in the wire is 54.62 A

Write the expression to calculate the current density. Here, J Is the current density Substitute the valtues in above equation. 54.62 2.81x105 1.94x10 A/m2 -6 Hence, the current density is 1.94 x10 A/m