# Homework Help: Find capacitance (calculus)

1. Mar 30, 2010

### blackblanx

1. The problem statement, all variables and given/known data

Determine the capacitance of two conducting plates facing each other at an angle as shown (in link) . Plate A and B have dimensions of 10x20 cm and 10x (20sec30) (angles in degrees)

2. Relevant equations
C=( $$\epsilon$$ A)/d

3. The attempt at a solution
not quite sure can someone help me get the ball rolling or the floor moving

#### Attached Files:

• ###### plates.bmp
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2. Mar 30, 2010

### rl.bhat

If you take one strip of the plate of width dx and length L.
The capacity of that strip is given by
ΔC = εο*L*dx/(d + d')
From the figure write down d' in terms of x and θ.
Find the integration to get the capacitance C.

3. Mar 31, 2010

### blackblanx

What are you using for d' ?

4. Mar 31, 2010

### rl.bhat

d' is the variance distance of the slanted plate from the horizontal line.
In the problem, numerical values are not correct.
One end of the slanted plate is 1 mm from the top plate,. And the other end is 0.1 mm from the top plate. So tan θ = 0.9 mm/0.1 mm which is not equal to tan(30)