Recent content by jilia

i don't really understand charge density. all i know is that it have 3 charge densities, volume, area, and linear. i just learned this today and i get ρ = −6q/πR3 not ρ = −6q/7πR3. can you help me solve this step by step?

how do you get

why do you have negative sign for the q(inside)? can you explain?