Cycle II AP Physics

John Dewey HS

Mr. Klimetz

Problems in Electrostatics I

Elementary Charges, Coulombs, and Fields

Answer the following questions in the spaces provided or on a separate sheet of paper. Be sure to employ proper problem-solving techniques throughout. Consult your AP Equations and Information sheets and textbook as necessary.

1.   Which of the following charge values are valid?

I      -3.50 C

II     3.20 x 10exp-19 C

III    -0.10 C

IV    1.60 x 10exp-20 C

V     -0.48 C

(A) I and II only

(B) III and V only

(C) II and V only

(D) II and IV only

(E) I, II, III and V only

2.   Point charge A possesses an excess of electrons. It has a charge of  -6.40  x 10exp-6 C. It is placed in contact with point charge B which has a charge of +3.20 x 10exp-6 C. Both point charges are brought into direct contact and then separated. Calculate (A) the number of excess fundamental charges at point charge A before contacting point charge B, (B) the number of deficient fundamental charges at point charge B before contacting point charge A, (C) the final charge of point charge A, (D) the final charge of point charge B, and (E) the total number of elementary charges transported.

3.     A point charge with a value +6.00 C is bought into direct contact with (A) of an automobile parked on the street, and (B) the fence gate at the entrance to school, and then separated. Calculate the respective charges of the point charge and each of the objects listed above after they are separated.

4.     The flow of electrons through a conductor is referred to as electric current. The units of electric current are in amperes (or amps). A one amp current is established in a conductor when 1 Coulomb of charge passes a given point every second. Calculate the number elementary charges which pass a given point in a particular conductor which is carrying a current of 20.0 amps over a period of 3 hours and 15 minutes.