Chapter 16         Sample Multiple Problems

1.         A piece of plastic has a net charge of +2.00 μC.  How many more protons than electrons does this piece of plastic have?

a.         1.25X1013

b.         1.25X1019

c.         2.50X1013

d.         2.50X1019

2.         Two charges are separated by a distance d and exert mutual attractive forces of F on each other.  If the charges are separated by a distance of d/3, what are the new mutual forces?

a.         F/3

b.         F/9

c.         3F

d.         9F

3.         A +4.0 C charge is at the origin and a +9.0 C charge is at x = 4.0 m.  Where on the x-axis can a third charge be placed so the net force on it is zero?

a.         0.50 m from +4.0 C

b.         0.60 m from +4.0 C

c.         1.6 m from +4.0 C

d.         2.4 m from +4.0 C

4.         Three point charges are located at the following positions: Q1 =

2.00 μC at x = 1.00 m; Q2 = 3.00 μC at x = 0; Q3 = -5.00 μC at x = -1.00 m.  What is the magnitude of the force on the 3.00 μC charge?

a.         5.40X10-2 N

b.         0.135 N

c.         8.10X10-2 N

d.         0.189 N

5.         Two point charges, separated by 1.5 cm, have charge values of +2.0 and -4.0 μC, respectively.  What is the magnitude of the electric force between them?

a.         -320 N

b.         320 N

c.         3.6X10-8 N

d.         8.0X10-12 N

6.         Charge +2q is placed at the origin and charge -q is placed at x = 2a.  Where can a third positive charge +q be placed so that the force on it is zero?

a.         3.4a

b.         6.8a

c.         8.6a

d.         9.3a

7.         Is it possible for two electrons to attract each other?

a.         Yes, they always attract.

b.         Yes, they will attract if they are close enough.

c.         Yes, they will attract if one carries a larger charge than the other.

d.         No, they will never attract.

8.         Three identical point charges of 2.0 μC are placed on the x-axis.  The first charge is at the origin, the second to the right at x = 50 cm, and the third is at the 100 cm mark.  What are the magnitude and direction of the electrostatic force which acts on the charge at the origin?

a.         0.18 N left

b.         0.18 N right

c.         0.36 N left

d.         0.36 N right

9.         The force between a 0.015 C charge and a 10.3 μC charge is 0.40 N.  How far apart are they?

a.         59 m

b.         39 m

c.         39 cm

d.         59 mm

10.       A force of 6.0 N acts on a charge of 3.0 μC when it is placed in a uniform electric field.  What is the magnitude of this electric field?

a.         18 MN/C

b.         2.0 MN/C

c.         0.50 MN/C

d.         130 MN/C

11.       Can electric field lines intersect in free space?

a.         Yes, but only at the midpoint between two equal like charges.

b.         Yes, but only at the midpoint between a positive and a negative charge.

c.         Yes, but only at the centroid of an equilateral triangle with like charges at each corner.

d.         No.

12.       A 5.0-C charge is 10 m from a small test charge of 1.0 nC.  What is the electric field at the 1.0 nC charge?

a.         4.5X106 N/C

b.         4.5X107 N/C

c.         4.5X108 N/C

d.         4.5X109 N/C

13.       A 5.0-C charge is 10 m from a small test charge of 1.0 nC.  What is the direction of the electric field at the 1.0 nC charge?

a.         toward the 5.0 C

b.         away from the 5.0 C

c.         perpendicular to a line joining the charges

d.         none of the above

14.       A 5.0 μC charge is placed at the 0 cm mark of a meterstick and a -4.0 μC charge is placed at the 50 cm mark.  What is the electric field at the 30 cm mark?

a.         4.0X105 N/C

b.         5.0X105 N/C

c.         9.0X105 N/C

d.         1.4X106 N/C

15.       Two point charges each have a value of 3.0 C and are separated by a distance of 4.0 m.  What is the electric field at a point midway between the two charges?

a.         zero

b.         9.0X107 N/C

c.         18X107 N/C

d.         4.5X107 N/C

1.         a

2.         d

3.         c

4.         d

5.         b

6.         b

7.         d

8.         a

9.         a

10.       b

11.       d

12.       c

13.       b

14.       d

15.       a