Physics
posted by Susie .
Consider the electric field created by a very long charged line of negative linear charge density 2.50 nC/m.
A small positive point charge of 8 mC moves from a distance of 9 cm to a distance of 17 cm.
How much work is done by the electric field?
Hint: The electric field for a long charged line is:
Express the result in the unit mJ and to three significant figures.

The Equation is E line = 1/(4piE0)(2lamda/r)

Since you have not provided the "hint", I used Gauss' Law to come up with
2*pi*R*L*E = L*q/eo
where eo is the coulomb's law constant "epsilonzero" = 8.89^10^12 N*m^2/C^2
and q is the charge per unit length
E(R) = q/(2 pi eo R)
Multiply that by Q = 8 mC and integrate with dR from R = 0.09 to 0.17 m
There should be a ln(17/8) term in the answer.
The work done will be positive since Q is moving in the opposite direction from the attractive force 
The hint is
E line = 1/(4piE0)(2lamda/r)
Are the answers the same even if I use Gauss' Law to come up with 2*pi*R*L*E = L*q/eo 
Isn't the work negative, because this is a positive charge moving in the opposite direction of the electric field?

Positive work must be done in order to make a positive charge go opposite the direction of the electric field.
F of Electric field> < + F of Positive charge
(If you did negative work, the positive charge would move in the direction of the field.)
Respond to this Question
Similar Questions

Physics
Consider the electric field created by a very long charged line of negative linear charge density 2.50 nC/m. A small positive point charge of 7 mC moves from a distance of 9 cm to a distance of 17 cm. How much work is done by the … 
PHYSICS
A charged disk of radius R that carries a surface charge density ó produces an electric field at a point a perpendicular distance z from the center of the disk, given by: Consider a disk of radius 10 cm and positive surface charge … 
Physics
A charged disk of radius R that carries a surface charge density σ produces an electric field at a point a perpendicular distance z from the center of the disk, given by: Edisk = (sigma/2e0) x(1(z/(square root(z^2 + R^2)) Consider … 
physics
Consider the electric field created by a very long charged line of negative linear charge density 2.50 nC/m. A small positive point charge of 12 mC moves from a distance of 7 cm to a distance of 18 cm. In mJ, how much work is done … 
Physics
An infinitely long line charge of uniform linear charge density λ = 3.00 µC/m lies parallel to the y axis at x = 2.00 m. A point charge of 4.70 µC is located at x = 1.50 m, y = 2.50 m. Find the electric field at x = 2.50 m, … 
Physics
An infinitely long line charge of uniform linear charge density λ = 3.00 µC/m lies parallel to the y axis at x = 2.00 m. A point charge of 4.70 µC is located at x = 1.50 m, y = 2.50 m. Find the electric field at x = 2.50 m, … 
physics E&M
I posted a question on here earlier but I wasn't able to solve from what the person had told me. An infinite line charge of uniform linear charge density lambda = 2.5 micro Coulombs lies parallel to the y axis at x = 0 m. A point … 
Physics
An infinitely long line of charge has linear charge density ë. Find the energy density of the electric field at a point a radial distance r from the wire. (Use the following as necessary: å0, ë, r.) 
3 physics question please help quick
Two point charges of opposite sign are brought close together. Which statement best describes the field lines of the combined point charges? 
Physics
An infinitely long, solid insulating cylinder with radius a has positive charge uniformly distributed throughout it with a constant charge per unit volume p. a) using Gauss's law, derive the expression for the electric field inside …