# Capacitance (farads) am I doing this right?

1. Feb 5, 2009

### phys-lexic

1. To make a parallel plate capacitor, you have available two flat plates of aluminum (area = 190 cm2), a sheet of paper (thickness = 0.10 mm, κ = 3.5), a sheet of glass (thickness = 2.0 mm, κ. = 7.0), and a slab of paraffin (thickness = 10.0 mm, κ = 2.0). Find each's capacitance; then enter the largest capacitance possible, of the three, in nF and the smallest in pF.

2. (capacitance) = ((epsilon not)x(Area)x(k)) / (d)

**d, or distance between the capacitors, would be the thickness of the paper/glass/paraffin right?**

-smallest = 3363 pF (paraffin)
-largest = 588.5 nF (paper)

when i enter the values on my webassign it says im wrong... are the values correct and just converted wrong or am i totally off [i did converted all the given values to meters before plugging them in to the equation]

2. Feb 5, 2009

### AssyriaQ

This is not what I get. I get different exponents. Can you show one example of how you calculated the capacitance?

3. Feb 5, 2009

### phys-lexic

in example, for paper i did

(Eo) (A) (k) (d)
(8.85E-12)x(1.9)x(3.5)... then divided by .0001 (thickness)

4. Feb 5, 2009

### phys-lexic

the equation i though to use was C = ( (Eo)x(A)x(k) ) / (d)

5. Feb 5, 2009

### AssyriaQ

The error lies in the conversion of the area; 190 cm$$^{2}\neq$$ 1.9 m$$^{2}$$.

6. Feb 5, 2009

### phys-lexic

oh wow... i was in a rush and forgot it was area... hha thanks alot