- #1
sachi
- 75
- 1
In a parallel plate capacitor with circular plates we're asked to find the magnitude and direction of the poynting vector, which logically should be pointing radially outwards. Let us say that the top plate is positively charged and the bottom is negatively charged. Therefore we have an E-field and D field pointing downwards. Since Jd (the displacement current) is the time derivative of D, we should find the current pointing downwards. We can then work out the resultant B-field which acts in the direction indicated by the right hand rule (i.e into the page on the left side of the capacitor and out of the page on the right side of the capacitor). Now use N= E X H and the left hand rule to give us the direction of energy flow. The E-field points downwards. This indicates that energy is flowing into the capacitor which makes no sense. I'm not too sure where I've gone wrong.