- Nov 2008

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here is a question:

http://i25.tinypic.com/8xlcfl.gif

there is endless wire uniformly charged \(\displaystyle \lambda=2*10^{-4}C/m\)

and close to it located a wire with \(\displaystyle l=0.12_m\)

which has 30 degree angle between him and the endless wire,and it charged in uniformed way so that the total charge on it is \(\displaystyle q=3*10^{-9}\)

the distance of the finite wire and the infinite wire is 0.08 meters

A.find the total force acted on the finite wire.

B.find it when \(\displaystyle \alpha=0 \)degrees and when \(\displaystyle \alpha=90 \)degrees.

gaus law for infinite wire i presume its length is l and distance r.

\(\displaystyle E2\pi r h=\frac{q}{\epsilon_0}\\\)

\(\displaystyle E=\frac{q}{\epsilon_0 2\pi r h}=\frac{\lambda h}{\epsilon_0 2\pi r h}=\frac{\lambda }{\epsilon_0 2\pi r }\\\)

\(\displaystyle \frac{q_2}{l_2}=\lambda_2\\\)

\(\displaystyle l_0=l_2\cos \alpha\\\)

\(\displaystyle \int_{0}^{l_0}Edl=\int_{0}^{l_0}\frac{\lambda }{\epsilon_0 2\pi r }dl\)

i sum along the finite wire

but the ditance from the infinite changes too.

so it should be a double integral

but its not a 2d body

??

http://i25.tinypic.com/8xlcfl.gif

there is endless wire uniformly charged \(\displaystyle \lambda=2*10^{-4}C/m\)

and close to it located a wire with \(\displaystyle l=0.12_m\)

which has 30 degree angle between him and the endless wire,and it charged in uniformed way so that the total charge on it is \(\displaystyle q=3*10^{-9}\)

the distance of the finite wire and the infinite wire is 0.08 meters

A.find the total force acted on the finite wire.

B.find it when \(\displaystyle \alpha=0 \)degrees and when \(\displaystyle \alpha=90 \)degrees.

gaus law for infinite wire i presume its length is l and distance r.

\(\displaystyle E2\pi r h=\frac{q}{\epsilon_0}\\\)

\(\displaystyle E=\frac{q}{\epsilon_0 2\pi r h}=\frac{\lambda h}{\epsilon_0 2\pi r h}=\frac{\lambda }{\epsilon_0 2\pi r }\\\)

\(\displaystyle \frac{q_2}{l_2}=\lambda_2\\\)

\(\displaystyle l_0=l_2\cos \alpha\\\)

\(\displaystyle \int_{0}^{l_0}Edl=\int_{0}^{l_0}\frac{\lambda }{\epsilon_0 2\pi r }dl\)

i sum along the finite wire

but the ditance from the infinite changes too.

so it should be a double integral

but its not a 2d body

??

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