# In the source RLC circuit , potential difference across R,Land C 30V ,60V and 100V respectively as shown in figure. The emf of source is

Since the capacitor and inductor are out of phase, the net potential across them is$\dpi{80} 100V-60V=40V$
Hence the emf of source=$\dpi{80} \sqrt{30^2+40^2}V=50V$