## PHYS208 Fundamentals of Physics II

October 12, 1992    Midterm Exam 1

1.

• What is the electric field at the surface of each?

Both are 1500 V/m.

• What is the electric field halfway to the center for both?

Conductor: 0 V; Insulator 750 V/m.

• What is the electric potential halfway to the center for both?

Conductor: 15 V; Insulator 20.6 V.

2. d.  Evaluate the capacitance per meter length of RG58/U cable.

98 pF/m

3. a.  What is the current in the circuit?

0.41 A

3. b.  What is the power dissipated by the lamp?

1.15 W

3. c.  What is the terminal voltage of either D-cell?

1.42 V

3. d.  Estimate how long the flashlight will burn brightly.

4. d.  Solve for the currents i1, i2, and the current through the lamp.

i1 = 2.59 A;  i2 = -2.31 A;  i1+i2 = 0.28 A;

4. e.  What is the power now dissipated by the lamp?

0.55 W

4. f.  What is the terminal voltage of the third D-cell added?

1.97 V

"http://www.physics.udel.edu/~watson/phys208/exams/mid1-92f-ans.html"
Last updated Oct. 7, 1997.
Copyright George Watson, Univ. of Delaware, 1997.