1. A long wire is connected to the terminals of battery. In 8 Seconds, 9.6x10 ra

Question

1. A long wire is connected to the terminals of battery. In 8 Seconds, 9.6x10 raised to the power of 20 electrons pass a cross section along the wire. Calculate the electric current in the wire. If the electrons flow from the left to right, in which direction is the current?
2. A 110meter long copper wire of radius 0.12mm is connected across a 1.5V battery.
Calculate: a. the resistance of the wire
b. the current passing through it.
3.The resistance of copper wire increases by a factor of 1.32when current flows through the wire compared to its resistance when no current flow and its temperature is 0degree Celsius. What is its temperature when the current flows?

Explanation / Answer

first:

I=N*abs(e)/t
where N: number of electrons , e=electron charge=-1.6*10^-19 C [abs(e) means take e without the negative sign]
t : time
so I = (9.6*10^20*1.6*10^-19 C)/8 s = 19.2 A

the direction of the current is opposite the direction of the motion of the electron so
the current flows from the right to left .

second:

R=*l/A , is the resistivity , l is the length , A is the cross-section Area , in case of copper =1.68×108

so R= 1.68*10^-8 *110 /(.12*10^-3)2

R=40.84

I=V/R => I = 1.5/40.84=36.71 mA

Rtoc/R0oc =1.32+1=2.32

the law states :

Rtoc=R0oc(1+T)

by substituting ==> =0.0039

T= 338.46 K= 65.46 oc

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.