Question

Which circle has minimum flux in the following figure?

circle P

circle Q

circle R

circle S

Answer 1

Circle Q

Step-by-step explanation:

The flux of a field through a surface is given by:

`\Phi = F A cos \theta`

where

F is the field strength

A is the area of the surface

`\theta` is the angle between the direction of the field and the normal to the surface

In the figure, we see that the 4 surfaces have different orientations, so different angle
`\theta`. In the formula, we see that the flux is maximum when
`\theta=0^(\circ)`, which occurs when the field is perpendicular to the surface, and the flux is zero when
`\theta=90^(\circ)`, (because
`cos 90^(\circ)=0`) which occurs when the field is parallel to the surface.

In the figure, we see that circle Q is parallel to the direction of the field, so in this case the field is zero, while in all the other cases is not.

So, the correct answer is

Circle Q