Answer to Question #234853 in Physics for Mosses07

Question

A butterfly net hangs from a circular loop of diameter 430 mm. You hold the loop horizontally in a region where the electric field is 180 N/Cdownward, as shown in (Figure 1).

(a) What is the electric flux through the net?

(b) Does the flux through the net increase or decrease if you rotate the loop so that it lies in a vertical plane?

Answer 1

a) The electric flux through the net is

$$\Phi=EA=E·\frac{\pi d^2}{4}=180·\frac{\pi·0.43^2}{4}=26.1\text{ Nm}^2\text{/C}.$$

b) It decreases (disappears) because the field lines are parallel to the loop plane and cannot go through it.