The plates of a parallel plate capacitor are square with a side of d = 0.78 cm a
ID: 2271831 • Letter: T
Question
The plates of a parallel plate capacitor are square with a side of d = 0.78 cm and the voltage across the plates is 3.46 V. The distance between the plates is 2.00 mm. One capacitor plate has an excess of electrons and the other has a matching deficit of electrons. What is the number of excess electrons?
Explanation / Answer
Apply Q = CV
First we need C which is found from C = kEA/d
C = (1)(8.85 X 10^-12)(.0078)(.0078)/(2 X 10^-3)
C = 2.69 X 10^-13 F
Q = (2.69 X 10^-13)(3.46)
Q = 9.31 X 10^-13
Divide that by the charge per electron
9.31 X 10^-13/1.6 X 10^-19 = 5.82 X 10^6 electrons