LAxC us. Tue 1106 PM History Bookmarks People Window Help secure https:llsession
ID: 1538302 • Letter: L
Question
LAxC us. Tue 1106 PM History Bookmarks People Window Help secure https:llsession. Khalid bukaid signed in as PHY 2049 801 Spring 2017 Exercise 25.12 of 15 Exercise 25.12. Part A Find the magntude of the aument densty in the wire, Aoopper wee has a square aross secton21mm Express your answer using two significant figures. on aside. The wire s45m long and aument of 33A The density of free electrons 85 x 10 m A/m? Incorrect Try Again: 2 attempts remaining Part B Find the magnitude of the electic feldin he wine significant figures Express your answer using two V/ms My Answers 9het up Part C WPXExplanation / Answer
side length, a=2.1 mm
area of cross section, A=a^2=(2.1*10^-2)^2 =44.1*10^-6 m^2
length of the wire, l=4.5 m
current, I=3.3 A
density of electron, n=8.5*10^28 electrons/m^3
a)
current density, j=I/A
=3.3/(44.1*10^-6)
=7.5*10^4 A/m^2
b)
use,
E=rho_copper*j
E=1.72*10^-8*7.5*10^4
E=1.29*10^-3 V/m
c)
drift speed, vd=j/n*e
and
time taken to cross the length,
t=l/vd
t=l/(j/n*e)
t=l*n*e/(j)
t=(4.5*8.5*10^28*1.6*10^-19)/(7.5*10^4)
t=8.16*10^5 sec
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