EXAM 2 November 6, 1987 PS 208
If you need a constant not given here or do not understand
a problem, please ask me about it. No notes, books, etc. may
be used during this exam.
2 -19
g = 9.8 m/sec e = 1.6 x 10 C
9 2 2
1/(4 pi epsilon ) = 9.1 x 10 N m / C
0
-7
mu / (4 pi) = 10 T m/ A
0
-31
The mass of the electron is 9.11 x 10 kg.
1. Four equal point charges Q are placed at the four corners of
a square of side a . Find V at the center of the square.
2. A battery with EMF V and internal resistance r is
connected across a single resistor of resistance R . For what
value of R will the power dissipated in the resistor be a
maximum? What will the maximum dissipated power be?
3. (From homework) Determine the
current through each battery in the --------V---r-------
figure. Note that the values of the | |
batteries and resistances have been R1 R2
changed so as to reduce the total | |
number of unknown quantities. |--------V---r-------|
| |
(The high side of all the R1 R2
batteries is to the right.) | |
---------V---r-------
4. A capacitor is made of two concentric cylinders of length L
and radii R and R , with a dielectric of constant kappa between
1 2
the cylinders. If the inside cylinder carries a charge +Q and
the outside cylinder carries a charge -Q , determine the electric
field in the dielectric, the potential difference between the
cylinders, and the capacitance of the device. Neglect end
effects.