Homework06

Homework06 - johnson (rj6247) hw 6 Opyrchal (121014) 1 This...

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

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: johnson (rj6247) hw 6 Opyrchal (121014) 1 This print-out should have 13 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A conductor with cross-sectional area 9 cm 2 carries a current of 10 A. If the concentration of free electrons in the conductor is 9 10 28 electrons / m 3 , what is the drift velocity of the electrons? Correct answer: 0 . 000770556 mm / s. Explanation: Let : I = 10 A , n = 9 10 28 electrons / m 3 , q e = 1 . 60218 10 19 C , and A = 9 cm 2 = 0 . 0009 m 2 . The current in a conductor is given by I = n q v d A , where n is the number of charge carriers per unit volume, q is the charge per carrier, v d is the drift velocity of the carriers and A is the cross section of the conduction. Solving for v d , we have v d = I n q A = 10 A 9 10 28 electrons / m 3 1 1 . 60218 10 19 C 1 . 0009 m 2 1000 mm 1 m = . 000770556 mm / s . 002 10.0 points A wire with a resistance R is lengthened to 8 . 1 times its original length by pulling it through a small hole. Find the resistance of the wire after it is stretched. Correct answer: 65 . 61 R . Explanation: Let : = 8 . 1 . The volume V of the wire is given by V = A, where is the length of the wire and A is the cross-sectional area. When the wire is stretched to a length , the volume will re- main the same. The new cross-sectional area is then, A = A A = A = A 8 .....
View Full Document

Page1 / 4

Homework06 - johnson (rj6247) hw 6 Opyrchal (121014) 1 This...

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

View Full Document Right Arrow Icon
Ask a homework question - tutors are online