Uhhmm....I can't remember the right formula and probably...you know the formula better than me currently. I'll explain to you how it works. First when it is in axial position, the rod is placed in vertical position and therefore, theta = 90 degrees or pi/2 radians. Now....according to the second condition, it is moved perpendicular to its perpendicular axis which means that it is rotated through 90 degrees through the axis which is perpendicular to its surface. Now, in the previous condition, the theta itself was 90 degrees and it is all the more rotated by more 90 degrees. So, either ways...if you take into consideration the angles in second case...it is 180 degrees. Substitute these values in the formula and probably...you'd get an answer.
hum so it would be E-(-E) = 2E. Hummm yes that can a heck of an explanation. How ever
What this will be; " variable plate capacitor connected to electroscope in series . The reading of the electro will decrease by?
1) increasing area of overlap of plates
2)decrease in distance betwn plates
3)placing paraffin in betwn them
4)decreasing battery potential?