Question 1

A parallel plate capacitor with plate separation of 4.0 cm has a plate area of 4.0 × 10-2 m2. What is the capacitance of this capacitor with air between these plates?

Accepted Answer

A)  8.9 × 10-11 F 
B)  8.9 × 10-12 F 
C)  8.9 × 10-13 F 
D)  8.9 × 10-14 F 
E)  8.9 × 10-15 F

Question 2

Several electrons are placed on a hollow conducting sphere. They

Accepted Answer

A)  clump together on the sphere's outer surface. 
B)  clump together on the sphere's inner surface. 
C)  become uniformly distributed on the sphere's outer surface. 
D)  become uniformly distributed on the sphere's inner surface. 
E)  become randomly distributed on the shere's outer and inner surfaces.

Question 3

FIGURE 20-1 
-Two parallel metal plates A and B carry positive and negative charges of equal strength, respectively, as shown in Figure 20-1. What is the correct direction for the equipotential lines for this charge configuration?
Choice I:
Vertical, along the y-axis
Choice II:
Horizontal, along the x-axis

Accepted Answer

A)  Choice I 
B)  Choice II 
C)  neither Choice I nor Choice II 
D)  both Choice I and Choice II

Question 4

The electron-volt is a unit of

Accepted Answer

A)  charge. 
B)  potential. 
C)  electric field. 
D)  electric force. 
E)  energy.

Question 5

A -4.0-μC charge is situated at the origin of an xy-coordinate system. What is the magnitude and direction of an electric potential at x = 6.0 m?

Accepted Answer

A)  1500 V along the +x-axis 
B)  6000 V along the +x-axis 
C)  -6000 V with no direction 
D)  4000 V along the +x-axis 
E)  4000 V with no direction

Question 6

The potential difference between the plates of a parallel plate capacitor with the plate separation of 6 cm is 60 V. What is the electric field between the plates of this capacitor?

Accepted Answer

A)  60 V/m 
B)  500 V/m 
C)  1000 V/m 
D)  2000 V/m 
E)  3600 V/m

Question 7

A charged particle with charge + 5.0 μC is initially at rest. It is accelerated through a potential difference of 500 V. What is the kinetic energy of this charged particle?

Accepted Answer

A)  2.5 × 10-3 J/m 
B)  2.5 × 10-3 J 
C)  2500 J 
D)  2500 J/m 
E)  0 J

Question 8

Equipotential lines and electric field lines meet perpendicular to one another.

Accepted Answer

A) True 
 B)False

Question 9

A parallel plate capacitor has a potential difference between the plates of 80 V. If the charge on one of the plates of the capacitor is +8.0 μC, what is the electrical energy stored by this capacitor?

Accepted Answer

A)  640 × 10-6 J 
B)  320 × 10-6 J 
C)  5.0 × 10-8 J 
D)  6.0 × 10-8 J 
E)  3.0 × 10-8 J

Question 10

A 4.0-μC charge is situated at the origin of an xy-coordinate system. What is the magnitude and direction of the electric potential at x = 6.0 m?

Accepted Answer

A)  1500 V along the +x-axis 
B)  4000 V along the +x-axis 
C)  4000 V with no direction, as it is a scalar quantity 
D)  6000 V along the +x-axis 
E)  6000 V with no direction, as it is a scalar quantity

Question 11

The work done in moving a positive charge against an electric field does not depend on the path chosen in moving the charge in that field. Based on the statement, what kind of force field is the electrostatic field?

Accepted Answer

A)  discrete 
B)  quantized 
C)  polarized 
D)  conservative 
E)  nonconservative

Question 12

For an electron moving in a direction opposite to the electric field

Accepted Answer

A)  its potential energy increases and its electric potential decreases. 
B)  its potential energy decreases and its electric potential increases. 
C)  its potential energy increases and its electric potential increases. 
D)  its potential energy decreases and its electric potential decreases. 
E)  both its potential energy and it electric potential remain constant.

Question 13

FIGURE 20-12 
-Two point charges of magnitude +4.0 μC and -4.0 μC are placed as shown in Figure 20-12. What is the potential difference between points A and B?

Accepted Answer

A)  48 V 
B)  96 V 
C)  0 V 
D)  96 × 103 V 
E)  48 × 103 V

Question 14

FIGURE 20-14 
-The equipotential surfaces between two spherical conductors are shown in Figure 20-14, with the value of the potential marked for each line. What is the potential difference between points G and D?

Accepted Answer

A)  +160 V 
B)  -160 V 
C)  +320 V 
D)  0 V 
E)  None of the other choices is correct.

Question 15

A capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference between the plates. If the separation between the plates is doubled, the magnitude of the electrical energy stored on the capacitor will

Accepted Answer

A)  double. 
B)  quadruple. 
C)  be cut in half. 
D)  be cut in fourth. 
E)  not change.

Question 16

FIGURE 20-3 
-Two point charges of magnitude +4.00 μC and +2.00 μC are placed at the opposite corners of a rectangle as shown in Figure 20-3.
(a) What is the potential at point A due to these charges?
(b) What is the potential at point B due to these charges?
(c) What is the potential difference between points A and B?

Accepted Answer

The answer of FIGURE 20-3 
-Two point charges of magnitude...

Question 17

A 20-μF capacitor has a charge of 60 μC. How much energy is stored in this capacitor?

Accepted Answer

A)  70 μJ 
B)  80 μJ 
C)  90 μJ 
D)  100 μJ 
E)  110 μJ

Question 18

A -4.0-μC charge is situated at the origin of an xy-coordinate system. What is the potential difference between a point x = 4.0 m and y = 2.0 m because of this charge?

Accepted Answer

A)  -9.0 × 103 V 
B)  9.0 × 103 V 
C)  -36 × 103 V 
D)  36 × 103 V 
E)  0 V

Question 19

A negative charge, if free, tries to move

Accepted Answer

A)  from high potential to low potential. 
B)  from low potential to high potential. 
C)  toward infinity. 
D)  away from infinity. 
E)  in the direction of the electric field.

Question 20

A 4-μF capacitor has a potential drop of 20 V between its plates. The electric potential energy stored in this capacitor is:

Accepted Answer

A)  0.8 μJ 
B)  8 μJ 
C)  80 μJ 
D)  800 μJ 
E)  8000 μJ

Exam 20: Electric Potential and Electric Potential Energy

A parallel plate capacitor with plate separation of 4.0 cm has a plate area of 4.0 × 10^-2 m². What is the capacitance of this capacitor with air between these plates?