Electromagnetism - Linear charge

[Jon Blind]

Homework Statement

q=1.602*10^-19 point 1

L=1mm=r1

v=1.1*10^6 at point 2

F=1.44*10^-12 at point 1

Homework Equations

E=(1/4πε)*(q/r)

ΔV=∫E*dr=(1/4πε)*q∫(1/r)=(1/4πε)*q*ln (r2/r1)

ΔU=ΔK=mv^2/2

ΔK=mv^2/2=ΔV*q=q*(1/4πε)*Q*(ln(r2/r1))

Q=F/E=1.44*10^-12/(q(4*pi*epsilon*(1.00*10^-3)^2))=1.00*10^-9

The Attempt at a Solution

mv^2/2=ΔV*q=q*(1/4πε)*Q*(ln(r2/r1))

r2=0.002m

IS this correct?

 

[gneill]

Your problem statement doesn't actually state a problem. What is to be analyzed or found?

What is the description of the scenario? Is that vertical charged rectangle meant to represent a short charged plate, part of in infinite plane of charge, a section through a disk of charge, or maybe just a short charged line segment? Something else?

Please provide a complete problem statement.

 

[Jon Blind]

Sorry but you have to calculate the length from position 1 to position 2. It's an infinite linecharge.

I can't understand where I went wrong in my calculations.

 

[rude man]

It's correct assuming v(L) = 0 and Q = line charge linear density which is usually written as λ and which has dimensions of QL^-1, not Q.

PS did not check math.