A current of I=8.0A is flowing in a typical extension cord of length L=3.00m. The cord is made of copper wire with diameter d=1.5mm. The charge of the electron is e=1.6×10−19C. The mass of the electron is m=9.1×10−31kg. The resisitivity of copper is rho=1.7×10−8Ω⋅m. The concentration of free electrons in copper is n=8.5×1028m−3.The population of the Earth is roughly six billion people. If all free electrons contained in this extension cord are evenly split among the humans, how many free electrons ( Ne) would each person get?

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Ne=1.8 *10^37

Explanation:

Current density J=Iₐ /(πr²)

=  8/(π* (1.5*10⁻³/2)²)= 4.53*10⁶ A/m²

Drift velocity =  J/ne =4.53*10⁶ /(8.5×1028 *1.6×10−19 ) = 3.33 ×10−4 m/s

volume = πr²h= π * (1.5*10⁻³/2)² * 3 = 5.3 ×10−6 m³

Ne=1.8 *10^37

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles