A hollow insulating sphere with an inner radius of 6.58 cm and outer radius of 11.7 cm has a uniform charge density of 79.9 μC/m3 distributed throughout the volume between.
If we want to use Gauss' Law to find the electric field at r = 17.2 cm, what "charge enclosed" should we use?
RHO = Q/V
a = .0658 m
b = .1170 m
r = .1720 m
therefore r > b > a
The Attempt at a Solution
i kno RHO = Q/V
i just don't kno what V to use
i've used v = 4/3(pi)(.1720^3)
i've used v = (4/3)(pi)(.1720^3 - .1170^3)
think i've used every combination of r
i kno i'm overlooking something incredibly simple