# In a region of space, the electric field is given by $\vec{E} = 8\hat{i} + 4\hat{j} + 3\hat{k}$ . The electric flux through a surface of area 100 units in the xy plane is

Q. In a region of space, the electric field is given by $\displaystyle \vec{E} = 8\hat{i} + 4\hat{j} + 3\hat{k}$ . The electric flux through a surface of area 100 units in the xy plane is

(a) 800 units

(b) 300 units

(c) 400 units

(d) 1500 units

Ans: (b)
Sol: $\displaystyle \vec{E} = 8\hat{i} + 4\hat{j} + 3\hat{k}$

Area vector is

$\displaystyle \vec{A} = 100 \hat{k}$ (As it perpendicular to XY Plane)

Electric flux

$\displaystyle \phi = \vec{E} . \vec{A}$

$\displaystyle \phi = (8\hat{i} + 4\hat{j} + 3\hat{k}) . (100 \hat{k})$

= 300 unit