Question

Flux will be minimum when electric field lines to area are

Answer 1

Answer:

perpendicular

Explanation:

when the angle between electric field lines and the area is 90 degrees the electric flux will be zero, mathematically:

electric flux = E.A

here cos(90)=0

so electric flux will be zero.

Answer 2

Note: The correct question must be provided with following options-

Flux will be minimum when electric field lines to the area are-

a) parallel

b) perpendicular

c) at angle

d) at distance

Explanation for correct option

b:

1. Because the electric flux formula is, $\phi =EAcos \theta$, the flux is zero when the angle is $90^{\circ}$ ($\because cos90^{\circ} =0$ )
2. This means that the surface will be parallel to the field lines, with no field lines crossing it.
3. Thus, the flux will be minimum i.e. zero when electric field lines are perpendicular to the area.

Explanation for incorrect options

a:

• If the electric field lines are parallel to the area then, the angle made will be $\theta=0^{\circ}$.
• This will result in maximum electric flux.

Thus, option a is incorrect.

c:

• If the electric field lines are at an angle there is no way to be sure that the resulting flux will be minimum, since the least flux we can obtain is zero.

Thus, option c is incorrect.

d:

• If electric field lines are at a distance from the area, it will result in some flux but it will still not be minimum.

Thus, option d is incorrect.

Hence, option b) is correct.

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