The critical load for a column of length l hinged at both ends and having flexural rigidity EI, is given by

A

$$P_c=\frac{\pi EI}{(L^{2})}$$

B

$$P_c=\frac{\pi^{2} EI}{(L^{2})}$$

C

$$P_c=\frac{\pi EI^{2}}{(L^{2})}$$

D

None of these