An infinitely long uniform line charge distribution of charge per unit length $$\lambda$$ lies parallel to the y-axis in the y-z plane at $$z = \frac{\sqrt{3}}{2} a$$ (see figure). If the magnitude of the flux of the electric field through the rectangular surface ABCD lying in the x-y plane with its centre at the origin is $$\frac{\lambda L}{n ε_0}$$ ($$ε_0$$ = permittivity of free space), then the value of n is