A cylindrical shell of radius 8.1 cm and length 247 cm has its charge density uniformly distributed on its surface. The electric field intensity at a point 20.3 cm radially outward from its axis (measured from the midpoint of the shell ) is 41800 N/C.
Given: ke =8.99×10^9 N·m^2 /C^2 . What is the net charge on the shell? Answer in units of C.
The Attempt at a Solution
I've been using E=[tex]\lambda[/tex]/2[tex]\pi[/tex][tex]\epsilon[/tex]r
I used the radius from the midpoint (20.3 cm) in place of the r in the equation and used the given E to solve for [tex]\lambda[/tex]. Then I found the area of the cylindrical shell by doing 2.47*2[tex]\pi[/tex]*.081+2[tex]\pi[/tex]*.081 and multiplied that by the [tex]\lambda[/tex]. I ended up with an answer of 6.1288E-7 the last time I did it.
Is the r supposed to be distance from the surface, maybe? or am I using the completely wrong equation?