Solve the following problems. Answers are given at the end of the problem set.

1.  (I) Find the electric field intensity produced by a 1.0 µC charge at the following distances.

a.  0.75 m

b.  1.5 m

2.  (II) Two charges, each equal to +2.90 µC, are placed at two corners of a square 0.500 m on each side as shown in the diagram below. Find the net electric field at the corner labeled P.

3.  (III) The electric field between the plates of a parallel plate capacitor is horizontal, uniform, and has a magnitude E. A small object mass 0.0250 kg and charge -3.10 µC is suspended in the field by a thread as shown below. The thread makes an angle of 10.5o with the vertical.

a.  What is the tension in the thread?

b.  What is the magnitude of the electric field?

4.  (III) Suppose the magnitude of the field between the plates from problem 3 is changed to and a new object with a charge of -2.05 µC is placed on the thread. The tension in the thread is 0.350 N and the thread makes an angle of 12o with the vertical.

a.  What is the mass of the object?

b.  What is the magnitude of the electric field?

5.  (II) A +5.0 µC charge experiences a 0.20 N force in the positive y direction. If the charge is replaced by with a -2.7 µC charge, what force will it experience?

6.  (II) An object with a charge of -3.6 µC and a mass of0.012 kg experiences an upward electric force due to an electric field, equal to its weight.

a.  Find the magnitude and direction of the magnetic field.

b.  If the electric charge on the object is doubled while its mass remains the same, find the magnitude and direction of its acceleration.

7.  (II)Two point charges of equal magnitude are 8.0 cm apart. At the midpoint of the line connecting them, their combined electric field has a magnitude of 45 N/C. What is the magnitude of the charges?

8.  (I) Make a qualitative sketch of the electric field line produced by two charges, +q and –q separated by a distance d.

9.  (II) Make a qualitative sketch of the electric field lines produced by the four charges, +q, -q, +q, and –q, arranged clockwise on the four corners of a square with sides of length d.

1a. 1.6 x104 N/C
1b. 0.40 x 104 N/C / 2.  1.46 x 105 N/C @ 14.6o to horizontal / 3.  a. 0.249 N
b.  1.46 x 104 N/C / 4.  / 5.  -0.11N
6.  a. -3.3 x 104 N/C
b.  9.81 m/s2 up / 7.  4.0 x 10-12 C / 8.  See below / 9.  See below