# Chap26_08 - .1 During the 4.0 min a 5.0 A current is set up...

This preview shows pages 1–2. Sign up to view the full content.

Chapter 26 26.1. During the 4.0 min a 5.0 A current is set up in a wire, how many (a) Coulombs and (b) electrons pass through any cross section across the wire’s width Δ q = i Δ t = 5.0 A 240 s = 1200 C Δ q = ne n = Δ q e = 1200 C 1.6 × 10 19 C = 7.5 × 10 21 electrons 26.4 A small but measurable current of 1.2 × 10 10 A exists in a copper wire whose diameter is 2.5 mm . The number of charge carriers per unit volume is 8.49 × 10 28 m 3 . Assuming the current is uniform, calculate the (a) current density and (b) the electron drift speed. (a) W can compute the current density from the definition. J = i A = 1.2 × 10 10 A π (.00125 m ) 2 = 2.44 × 10 5 A / m 2 (b) Now that we know J, we can compute the velocity J = ρ v = (# of particles / m 3 ) ( chg / particle ) = 8.49 × 10 28 m 3 1.6 × 10 19 C = 1.39 × 10 10 C / m 3 v = J = 2.44 × 10 5 A / m 2 1.39 × 10 10 C / m 3 = 1.8 × 10 15 m / s 26.7 A beam contains 2 × 10 8 double charged positive ions per cubic centimeter, all of which are

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 2

Chap26_08 - .1 During the 4.0 min a 5.0 A current is set up...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online