Question

The point of this problem is to show how slowly electrons travel on average through a...

The point of this problem is to show how slowly electrons travel on average through a thin wire, even for large values of current.

A wire made from copper with a cross-section of diameter 0.740 mm carries a current of 13.0 A. Calculate the "areal current density"; in other words, how many electrons per square meter per second flow through this wire? (Enter your answer without units.)

The density of copper is 8.99 g/cm3, and its atomic mass is 63.8. Assuming each copper atom contributes one mobile electron to the metal, what is the number density of free charges in the wire, in electrons/m3? (Enter your answer without units.)

Use your results to calculate the drift speed (i.e., the average net speed) of the electrons in the wire.

Due to thermal motion, the electrons at room temperature are randomly traveling to and fro at 1.11×105 m/s, even without any current. What fraction is the current's drift speed, compared to the random thermal motion?

Homework Answers

Answer #1

13.0A means 13.0 C of charge per second passing a given point. This corresponds to 13/1.67x10^-19 = 7.78x10^19 electrons per second

Or an electron density of 7.78x10^19/(π*(0.37x10^-3)^2) = 18.13x10^26 electron per m^2 per second

B) There are 8.99g/cm^3/63.8g/mol*6.022x10^23molecule... electron/molecule
= 1.68x10^23 electron/cm^3 = 23x10^26 electrons/m^3

C) vd = J/(n*q) = 13.0/(π*(0.37x10^-3)^2)/(23x10^26*1.67*10^-19   

D) we have 13.0/(π*(0.37x10^-3)^2)/(23x10^26*1.67*10^-19/1.1x105 = 8.99x10^-9   

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
Calculate the average drift speed of electrons traveling through a copper wire with a crosssectional area...
Calculate the average drift speed of electrons traveling through a copper wire with a crosssectional area of 30 mm2 when carrying a current of 30 A (values similar to those for the electric wire to your study lamp). Assume one electron per atom of copper contributes to the current. The atomic mass of copper is 63.5 g/mol and its density is 8.93 g/cm3 . Avogadro’s number is 6.022 × 1023 and the fundamental charge is 1.602 × 10−19 C. Answer...
Delta airlines case study Global strategy. Describe the current global strategy and provide evidence about how...
Delta airlines case study Global strategy. Describe the current global strategy and provide evidence about how the firms resources incompetencies support the given pressures regarding costs and local responsiveness. Describe entry modes have they usually used, and whether they are appropriate for the given strategy. Any key issues in their global strategy? casestudy: Atlanta, June 17, 2014. Sea of Delta employees and their families swarmed between food trucks, amusement park booths, and entertainment venues that were scattered throughout what would...
Discuss how the respective organizations’ relations with stakeholders could have potentially been affected by the events...
Discuss how the respective organizations’ relations with stakeholders could have potentially been affected by the events that took place at Enron and how the situation could have been dealt with differently to prevent further damage? THE FALL OF ENRON: A STAKEHOLDER FAILURE Once upon a time, there was a gleaming headquarters office tower in Houston, with a giant tilted "£"' in front, slowly revolving in the Texas sun. The Enron Corporation, which once ranked among the top Fortune 500 companies,...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT