Question

The electric flux through a plane surface of area 200 cm2

in a region of uniform electric field 20 N/C is

0.2 N m2

/C. Find the angle between electric field and normal to the surface.​

Answer 1

Answer:

Given,

Electric field, E=20NC −1

Area, A=10×10

−4 m 2 A

Electric Flux ϕ=E.Acosθ=20×10×10

−4 cos60 o =0.01Vm

Answer 2

Given:

Area of the plane surface (A) $=200$ $cm^{2}$ = $200$ × $10^{-4}$ $m^{2}$

Electric field strength (E) $= 20 N/C$

Electric flux through the surface (∅) $= 0.2 Nm^{2}$

To find:

Angle between electric field and normal to the surface (θ).

Explanation:

• Electric flux is the number of electric field lines passing through a given area.
• Its SI unit is $Nm^{2}$ (Newton metre square).
• According to its definition,

Flux (∅) = Electric field (E) × Area (A) × sinθ

Substituting the values, we get

$0.2 = 20$ × $200$ × $10^{-4}$ sinθ

Therefore,

sinθ = 0.5 ; or

θ = 30°

Final answer:

Hence, the angle between electric field and surface is 30°.