What's the voltage over each component?

Mathematica, 33 bytes

So close to Pyth...

l/Tr[l={#,#2(x=100Pi*I),1/x/#3}]&

This is an unnamed function, which takes R, L and C as its three arguments and returns a list of complex numbers as the result (in the required order VR, VL, VC). Example usage:

l/Tr[l={#,#2(x=100Pi*I),1/x/#3}]&[1, 1, 0.00001]
(* {0.0548617 + 0.22771 I, -71.5372 + 17.2353 I, 72.4824 - 17.463 I} *)

Pyth, 30 29 28 bytes

L*vw*100.l_1)K[Qy0c1y1)cRsKK

Try it online.

Octave / Matlab, 53 51 bytes

function f(R,L,C)
k=-.01j/pi;Z=[R L/k k/C];Z/sum(Z)

Try it online

Thanks to @StewieGriffin for removing two bytes.