- Derivation of Capacitance
vs. A and d
- Write down the integral form of Gauss' law.
- Examine the Gaussian surface shown
in the diagram above. What is the
value of the electric field insidethe top plate? Hint: There is
never an electric
field inside a conductor when no electric current is present!
- Using the results above and the notation
E to represent the uniform electric
field between the two plates, find an expression for the net charge on
plate, q, in relation to E.
- Use the relationship between V, E,
and d and the definition of capacitance to
derive an expression of the capacitnace of a parallel plate capacitor that
depends on A , d and k(kappa)
where A is the area of the plates, d is their
separation and k(kappa)
is a quantity called the dielectric constant and is a
property of the insulating material that separates the two plates.
- Use one of your actual areas and spacings
from the measurements you made
in class to calculate a value of C. How does the calculated value of C
with the directly measured value?
your results to the InfoMall
- Find two different discussions of capacitance
from two different levels of
textbooks on the InfoMall. Examine their results for a parallel
and for combining capacitors in parallel or in series. Include short quotes
from each source and give the complete citation for each reference.
- Compare your experimental results
from class to your readings in the
Borrowed by RGF and
VPC , at UNL, 10/2/97 from
© 1990-93 Dept. of Physics & Astronomy, Dickinson CollegeSupported
by FIPSE (U.S. Dept. of Ed.) and NSF