Question -
Answer -
(a) Electricfield intensity, 
= 3 × 103 îN/C
Magnitudeof electric field intensity, 
= 3 × 103 N/C
Side of the square, s =10 cm = 0.1 m
Area of the square, A =s2 = 0.01 m2
The plane of the square isparallel to the y-z plane. Hence, angle between the unitvector normal to the plane and electric field, θ = 0°
Flux (Φ) through the planeis given by the relation,
Φ= 
= 3 × 103 × 0.01× cos0°
= 30 N m2/C
(b) Planemakes an angle of 60° with the x-axis. Hence, θ =60°
Flux, Φ == 3 × 103 × 0.01× cos60°
= 15 N m2/C