Electrical Engineering

Electric Circuits & Fields Solutions

Question:
The picture on the right shows a plate capacitor.
You may assume that the two plates are very
large compared to the separation between the
plates (i.e. you may treat them as 'infinite'
planes).
area
A
11
+
+
The plates are charged to +Q, each plate has an
area of A, and the plates are separated by a
distance d. The x-axis in this problem is pointing
from the negative to the positive plate, with the
origin at the negative plate. The electric field at
point 2 has a magnitude of E.
-Q
→x(mm)
46
X-0
12
E = 3000 A = 1 m2
d = 8 mm
Ep = 8.85 x 10-12
Nm2
Part A:
a. In the picture, sketch the electric field between the plates by drawing the field lines.
b. Find the surface charge density n on each plate.
c. What is the electric field strength at point 1?
d. What is the charge Q on the plates?
e. What is the electric field strength at point 3?