
Answer:
electric flux is 280  Nm²/C Â
so correct option is D 280  Nm²/C
Explanation:
radius r = 0.50 m
angle = 30 degree
field strength = 713 N/C
to find out
the electric flux through the surface
solution
we find here electric flux by given formula that is
electric flux = field strength × area× cos∅  .......1
here area = πr² = π(0.50)²
put here all value in equation  1
electric flux = field strength × area× cos∅ Â
electric flux = 713 × π(0.50)² × cos60
we consider the cosine of the angle between the direction of the field and the normal to the surface of the disk
so we use cos60
electric flux = 280  Nm²/C
so correct option is D 280  Nm²/C