E&M capacitors

  • Thread starter Qyzren
  • Start date
  • #1
44
0
Two identical, oppositely-charged, conducting plates of area 2.50cm² are separated by a dielectric 1.80 mm thick, with a dielectric constant of 3.60. The resultant electric field in the dielectric is 1.2*10^6 V/m.

a)Compute the charge per unit area on the conducting plate.
b)Compute the charge per unit area on the surfaces of the dielectric.

The Attempt at a Solution


for part a). I used gauss's law for dielectric.
Q/A = K*epsilon_0*E = 3.60*8.85*10^-12*1.2*10^6 = 3.82*10^-5 C/m² which is correct.

However i haven't got a single clue how to do part b. But the answer is suppose to be 2.76*10^-5 C/m². Can someone please help me figure out how this answer was obtained?
 

Answers and Replies

  • #2
Meir Achuz
Science Advisor
Homework Helper
Gold Member
3,530
114
For b, they must mean bound surface charge density, which equals the normal component of the polarization vector P.
 
  • #3
44
0
thank you for help. i managed to figure it out now with your tip :)
 

Related Threads on E&M capacitors

  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
4
Views
4K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
0
Views
3K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
6
Views
2K
Top