(a) The above figure (a) shows a nonconducting rod of length $L=6.00cm$ and uniform linear charge density $λ=+3.68pC/m$. Assume that the electric potential is defined to be $V=0$ at infinity. What is $V$ at point $P$ at distance $d=8.00cm$ along the rod's perpendicular bisector? (b) Figure (b) shows an identical rod except that one half is now negatively charged. Both halves have a linear charge density of magnitude $3.68pC/m$. With $V=0$ at infinity, what is $V$ at $P$?