Question

In explaining the electric flux topic, there was an example about the fishing net catching fishes and it was told that the net catches more fishes when it's perpendicular to the flow of water and that the number of fishes being catched is reduced when the net is at an angle (say 60 degree) .
and my question is " Won't the number of fishes being caught be the same in both the cases because the area remains the same ? why and why not ? "

Answer 1

Dear student,
I appreciate your efforts to clear even simple but useful doubts. The number of fishes won't be the same in both cases. cthe area of net remains the same, but the thing is the depth to which it reach is reduced in the second case. Fishes moves along the current. When you vertically(perpendicular to the flow) dip the net, more depth is covered, which means more fishes enter in it, for a constant width. This is not the case when the net is falling in an angle. Let's do a simple experiment for better clarification. Take a candle, light it. Now take a book and place it vertically on the side of the candle to get a shadow of it on the wall. Now tilt the book, and slowly make it horizontal. As you tilt the book, you will see the area of the shadow decreases. Now assume the light to be the fish( or the current of water) book to be the net. Well, when did you got more fish in the net? That's how it works.
Thank you.