I tried a few things with this question, but kept coming up with anincorrect ans
ID: 1681420 • Letter: I
Question
I tried a few things with this question, but kept coming up with anincorrect answer. Any help would be much appreciated!A cylindrical shell of radius 8.4 cm and length
262 cm has its charge density uniformly dis-
tributed on its surface. The electric field
intensity at a point 28.3 cm radially outward
from its axis (measured from the midpoint of
the shell ) is 40000 N/C.
Given: ke = 8.99 × 10^9 N · m^2/C^2 .
a) What is the net charge on the shell? (answer in units ofC)
b) What is the electric field at a point 4.24 cm
from the axis? (answer in units of N/C)
Explanation / Answer
Gauss' law gives E = /(2r_0) for a cylinder ofsufficient length. That is, E = 2k/r. At r=.283 m we aregiven E = 40000 N/C. Plugging this in, we find = 6.296E-7C/m. The charge on the shell is equal to the length times the linearcharge density, . Use the formula for the electric field above with the new r to findthe electric field at the new distance.