Two long cylindrical insulating thin shells (both of radius a) are parallel to each other. The cylindrical axes separated by b> 2a. One shell is uniformly charged with a surface charge density + 0, the other is uniformly charged with a surface charge density - σ. (a) Find the electric field at point O on the axis of the positively charged shell (Hint: the superposition principle); (b) Find the electric potential difference VA - VB (Hint: the superposition principle) 8 D +0 -0

Two long cylindrical insulating thin shells (both of radius a) are parallel to each other. The cylindrical axes separated by b> 2a. One shell is uniformly charged with a surface charge density + 0, the other is uniformly charged with a surface charge density - σ. (a) Find the electric field at point O on the axis of the positively charged shell (Hint: the superposition principle); (b) Find the electric potential difference VA - VB (Hint: the superposition principle) 8 D +0 -0