A square surface of side L meter in the plane of the paper is placed in a uniform electric field E (volt/m) acting along the same plane at an angle θ with the horizontal side of the square as shown in figure. The electric flux linked to the surface, in units of volt-m, is

A square surface of side L meter in the plane of the paper is placed in a uniform electric field E (volt/m) acting along the same plane at an angle θ with the horizontal side of the square as shown in figure. The electric flux linked to the surface, in units of volt-m, is Correct Answer Zero

CONCEPT:

ELECTRIC FLUX

• Electric flux is defined as the number of electric lines force passing normally through a given area held inside an electric field. 
• Electric flux is given by

ϕ_E = E.dA = EdA Cosθ 

Where θ = Angle between area vector and uniform electric field.

[ alt="download" src="//storage.googleapis.com/tb-img/production/20/08/download.png" style="width: 284px; height: 178px;"> 

• When the angle between the electric field and area vector is  

1. θ =0°, Then the electric flux is maximum
2. θ = 90°^, Then  the  electric flux is minimum

[ alt="Electricflux" src="//storage.googleapis.com/tb-img/production/20/08/Electricflux.png" style="width: 750px; height: 241px;">   

CALCULATION:

• The electric flux linked to the surface is given by

⇒ Φ_E = E .dA = EdA Cosθ      ------(1)

The angle between the electric field line and area vector is 90⁰, 

∴ θ = 90° 

Then equation 1 can be written as,

⇒ Φ_E = E dA Cos90° = 0

• The total flux, ϕ_E = 0. Option 1 is the correct answer