## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

$-2.025 Nm^{2}/C$
Electric flux $\phi$ through any surface is given as: $\phi= E.A=EAcos\theta$ Here, $\theta=90^{\circ}+30^{\circ}=120^{\circ}$ $E=180 N/C$, $A= 0.15\times 0.15m^{2}=0.0225m^{2}$ Hence, $\phi=180 \times0.0225\times cos 120^{\circ}$$=-2.025 Nm^{2}/C$ The negative sign shows that it is travelling into the surface.