Question 1

Electric charges of the same sign

Accepted Answer

A) also have the same magnitude. 
B) attract each other. 
C) repel each other. 
D) exert no forces on each other. 
E) None of these is correct. 
A) also have the same magnitude. 
B) attract each other. 
C) repel each other. 
D) exert no forces on each other. 
E) None of these is correct. C

Question 2

Two positive charges (+8.0 mC and +2.0 mC)are separated by 300 m.A third charge is placed at distance r from the +8.0 mC charge in such a way that the resultant electric force on the third charge due to the other two charges is zero.The distance r is

Accepted Answer

A) 0.25 km 
B) 0.20 km 
C) 0.15 km 
D) 0.13 km 
E) 0.10 km 
A) 0.25 km 
B) 0.20 km 
C) 0.15 km 
D) 0.13 km 
E) 0.10 km B

Question 3

Which of the following statements about electric field lines is not true?

Accepted Answer

A) The number of lines leaving a positive charge or entering a negative charge is proportional to the charge. 
B) The lines begin on positive charges and end on negative charges. 
C) The density of the lines (the number per unit area perpendicular to the lines)is proportional to the magnitude of the field at that point. 
D) Electric field lines cross midway between charges that have equal magnitude and sign. 
E) The direction of each line indicates the direction that a positively charged particle would move if placed at that point in the electric field. 
A) The number of lines leaving a positive charge or entering a negative charge is proportional to the charge. 
B) The lines begin on positive charges and end on negative charges. 
C) The density of the lines (the number per unit area perpendicular to the lines)is proportional to the magnitude of the field at that point. 
D) Electric field lines cross midway between charges that have equal magnitude and sign. 
E) The direction of each line indicates the direction that a positively charged particle would move if placed at that point in the electric field. D

Question 4

The force between two very small charged bodies is found to be F.If the distance between them is tripled without altering their charges,the force between them becomes

Accepted Answer

A) 9F 
B) 3F 
C) F/3 
D) F/9 
E) 1/F3 
A) 9F 
B) 3F 
C) F/3 
D) F/9 
E) 1/F3

Question 5

A positive charge of 63.0 nC is 15.0 cm from a negative charge of 45.0 nC.The force on one of the charges due to the other is approximately

Accepted Answer

A) 1.13 $\times$ 10-3 N 
B) 1.13 $\times$ 10-7 N 
C) 1.02 $\times$ 107 N 
D) 1.25 $\times$ 10-13 N 
E) 1.02 $\times$ 10-6 N 
A) 1.13 $\times$ 10-3 N 
B) 1.13 $\times$ 10-7 N 
C) 1.02 $\times$ 107 N 
D) 1.25 $\times$ 10-13 N 
E) 1.02 $\times$ 10-6 N

Question 6

Electric charges of the opposite sign

Accepted Answer

A) also have the same magnitude. 
B) attract each other. 
C) exert no forces on each other. 
D) repel each other. 
E) None of these is correct. 
A) also have the same magnitude. 
B) attract each other. 
C) exert no forces on each other. 
D) repel each other. 
E) None of these is correct.

Question 7

Charges q1 and q2 exert repulsive forces of 10 N on each other.What is the repulsive force when their separation is decreased so that their final separation is 80% of their initial separation?

Accepted Answer

A) 16 N 
B) 12 N 
C) 10 N 
D) 8.0 N 
E) 6.4 N 
A) 16 N 
B) 12 N 
C) 10 N 
D) 8.0 N 
E) 6.4 N

Question 8

An electron is moving horizontally east in an electric field that points vertically upward.The electric force on the proton is

Accepted Answer

A) zero. 
B) upward. 
C) downward. 
D) to the west. 
E) to the east. 
A) zero. 
B) upward. 
C) downward. 
D) to the west. 
E) to the east.

Question 9

An oil droplet of mass 1.00 $\times$ 10-14 kg loses an electron while it is in an electric field of 1.00 $\times$106 N/C.The resulting change in the acceleration of the oil droplet is approximately

Accepted Answer

A) 1.76 $\times$ 1017 m/s2  
B) 16.0 m/s2  
C) 1.60 m/s2  
D) 1.76 $\times$ 1018 m/s2  
E) 176 m/s2  
A) 1.76 $\times$ 1017 m/s2  
B) 16.0 m/s2  
C) 1.60 m/s2  
D) 1.76 $\times$ 1018 m/s2  
E) 176 m/s2

Question 10

The Coulomb's force between a proton and an electron is 2.27$\times$1039 times greater than the gravitational force.If the two forces were equal,what should the size of the elementary charge be

Accepted Answer

A) 1.60 $\times$ 10-19 C 
B) 3.36 $\times$ 10-39 C 
C) 1.23 $\times$ 10-77 C 
D) 2.27 $\times$ 10-39 C 
E) 4.41 $\times$ 10-40 C 
A) 1.60 $\times$ 10-19 C 
B) 3.36 $\times$ 10-39 C 
C) 1.23 $\times$ 10-77 C 
D) 2.27 $\times$ 10-39 C 
E) 4.41 $\times$ 10-40 C

Question 11

An electric dipole p makes an angle of 30S1U1P1$\circ$S1S1P0 with a uniform electric field of magnitude 300 N/C.If the torque on the dipole is 3.00 $\times$ 10-12 N · m then calculate the magnitude of the dipole moment p.

Accepted Answer

A) 2.00 $\times$ 10-14 C · m 
B) 1.00 $\times$ 10-14 C · m 
C) 4.00 $\times$ 10-14 C · m 
D) 1.15 $\times$ 10-14 C · m 
E) 1.73 $\times$ 10-14 C · m 
A) 2.00 $\times$ 10-14 C · m 
B) 1.00 $\times$ 10-14 C · m 
C) 4.00 $\times$ 10-14 C · m 
D) 1.15 $\times$ 10-14 C · m 
E) 1.73 $\times$ 10-14 C · m

Question 12

Use the picture for the next problem.   A negatively charged particle moving with speed v enters a region of uniform electric field E.
-If the charge q = 1 nC,mass m = 1 $\times$ 10-14 kg,speed v = 105 m/s,the electric field strength E = 2 $\times$ 105 V/m,and width,w,of the electric field is 0.2 m,what is the speed of the particle when it emerges from the other side?

Accepted Answer

A) 1.0 $\times$ 105 m/s 
B) 4.0 $\times$ 104 m/s 
C) 1.08 $\times$ 105 m/s 
D) 1.4 $\times$ 105 m/s 
E) 1.8 $\times$ 105 m/s 
A) 1.0 $\times$ 105 m/s 
B) 4.0 $\times$ 104 m/s 
C) 1.08 $\times$ 105 m/s 
D) 1.4 $\times$ 105 m/s 
E) 1.8 $\times$ 105 m/s

Question 13

Protons

Accepted Answer

A) are about 2000 times more massive than electrons. 
B) are about 2000 times less massive than electrons. 
C) have 2000 times the charge of electrons. 
D) have 1/2000 the charge of electrons. 
E) can have any amount of charge. 
A) are about 2000 times more massive than electrons. 
B) are about 2000 times less massive than electrons. 
C) have 2000 times the charge of electrons. 
D) have 1/2000 the charge of electrons. 
E) can have any amount of charge.

Question 14

A particular nucleus of the element erbium contains 68 protons and 90 neutrons.What is the total charge of the erbium nucleus?

Accepted Answer

A) zero 
B) 1.4 $\times$ 10-17 C 
C) 2.5 $\times$ 10-17 C 
D) 1.1 $\times$ 10-17 C 
E) 3.5 $\times$ 10-18 C 
A) zero 
B) 1.4 $\times$ 10-17 C 
C) 2.5 $\times$ 10-17 C 
D) 1.1 $\times$ 10-17 C 
E) 3.5 $\times$ 10-18 C

Question 15

Two small spheres repel one another electrostatically.Which of the following statements must be true?

Accepted Answer

A) both have the same charge 
B) neither is charged 
C) both are charged 
D) at least one sphere is charged 
E) they are oppositely charged 
A) both have the same charge 
B) neither is charged 
C) both are charged 
D) at least one sphere is charged 
E) they are oppositely charged

Question 16

If nonelectric forces are negligible,a positively charged particle released from rest in a nonuniform electric field

Accepted Answer

A) moves perpendicular to the field with constant velocity. 
B) moves with constant velocity parallel to the field. 
C) accelerates in the direction of the field. 
D) accelerates perpendicularly to the field. 
E) moves only along equipotential lines. 
A) moves perpendicular to the field with constant velocity. 
B) moves with constant velocity parallel to the field. 
C) accelerates in the direction of the field. 
D) accelerates perpendicularly to the field. 
E) moves only along equipotential lines.

Question 17

Three charges are located at 100-m intervals along a horizontal line: a charge of -3.0 C on the left,+2.0 C in the middle,and +1.0 C on the right.What is the resultant force on the 1.0 C charge due to the other two?

Accepted Answer

A) 1.1 $\times$ 106 N to the right 
B) 1.1 $\times$ 106 N to the left 
C) 2.5 $\times$ 106 N to the right 
D) 2.5 $\times$ 106 N to the left 
E) 4.5 $\times$ 107 N to the right 
A) 1.1 $\times$ 106 N to the right 
B) 1.1 $\times$ 106 N to the left 
C) 2.5 $\times$ 106 N to the right 
D) 2.5 $\times$ 106 N to the left 
E) 4.5 $\times$ 107 N to the right

Question 18

Electrons

Accepted Answer

A) are about 2000 times more massive than protons. 
B) are about 2000 times less massive than protons. 
C) have 2000 times the charge of protons. 
D) have 1/2000 the charge of protons. 
E) can have any amount of charge. 
A) are about 2000 times more massive than protons. 
B) are about 2000 times less massive than protons. 
C) have 2000 times the charge of protons. 
D) have 1/2000 the charge of protons. 
E) can have any amount of charge.

Question 19

A point charge of +35 nC is above a point charge of -35 nC on a vertical line.The distance between the charges is 4.0 mm.What are the magnitude and direction of the dipole moment   ?

Accepted Answer

A) zero 
B) 1.4 pC · m up 
C) 1.4 pC · m down 
D) 2.8 pC · m up 
E) 2.8 pC · m down 
A) zero 
B) 1.4 pC · m up 
C) 1.4 pC · m down 
D) 2.8 pC · m up 
E) 2.8 pC · m down

Question 20

A molecule of HCl has a dipole moment of 3.39 $\times$ 10-30 C · m.If we assume full donation of the hydrogen electron to the chlorine,then calculate the distance between the charge centers.

Accepted Answer

A) 4.72 $\times$ 1010 m 
B) 1.06 $\times$ 10-11 m 
C) 4.24 $\times$ 10-11 m 
D) 2.12 $\times$ 10-11 m 
E) 2.44 $\times$ 10-11 m 
A) 4.72 $\times$ 1010 m 
B) 1.06 $\times$ 10-11 m 
C) 4.24 $\times$ 10-11 m 
D) 2.12 $\times$ 10-11 m 
E) 2.44 $\times$ 10-11 m

Exam 21: The Electric Field I: Discrete Charge Distributions

Electric charges of the same sign

Two positive charges (+8.0 mC and +2.0 mC)are separated by 300 m.A third charge is placed at distance r from the +8.0 mC charge in such a way that the resultant electric force on the third charge due to the other two charges is zero.The distance r is

Which of the following statements about electric field lines is not true?

The force between two very small charged bodies is found to be F.If the distance between them is tripled without altering their charges,the force between them becomes

A positive charge of 63.0 nC is 15.0 cm from a negative charge of 45.0 nC.The force on one of the charges due to the other is approximately

Electric charges of the opposite sign

Charges q1 and q2 exert repulsive forces of 10 N on each other.What is the repulsive force when their separation is decreased so that their final separation is 80% of their initial separation?

An electron is moving horizontally east in an electric field that points vertically upward.The electric force on the proton is

An oil droplet of mass 1.00 ×\times× 10-14 kg loses an electron while it is in an electric field of 1.00 ×\times× 106 N/C.The resulting change in the acceleration of the oil droplet is approximately

The Coulomb's force between a proton and an electron is 2.27 ×\times× 1039 times greater than the gravitational force.If the two forces were equal,what should the size of the elementary charge be

An electric dipole p makes an angle of 30 ∘\circ∘ with a uniform electric field of magnitude 300 N/C.If the torque on the dipole is 3.00 ×\times× 10-12 N · m then calculate the magnitude of the dipole moment p.

Protons

A particular nucleus of the element erbium contains 68 protons and 90 neutrons.What is the total charge of the erbium nucleus?

Two small spheres repel one another electrostatically.Which of the following statements must be true?

If nonelectric forces are negligible,a positively charged particle released from rest in a nonuniform electric field

Three charges are located at 100-m intervals along a horizontal line: a charge of -3.0 C on the left,+2.0 C in the middle,and +1.0 C on the right.What is the resultant force on the 1.0 C charge due to the other two?

Electrons

A point charge of +35 nC is above a point charge of -35 nC on a vertical line.The distance between the charges is 4.0 mm.What are the magnitude and direction of the dipole moment ?

A molecule of HCl has a dipole moment of 3.39 ×\times× 10-30 C · m.If we assume full donation of the hydrogen electron to the chlorine,then calculate the distance between the charge centers.

Systems of Measurement

Motion in One Dimension

Motion in Two and Three Dimensions

Newtons Laws

Applications of Newtons Laws

Work and Energy

Conservation of Energy

Systems of Particles and Conservation of Linear Momentum

Rotation

Conservation of Angular Momentum

Gravity

Static Equilibrium and Elasticity

Fluids

Oscillations

Wave Motion

Superposition and Standing Waves

Temperature and the Kinetic Theory of Gases

Heat and the First Law of Thermodynamics

The Second Law of Thermodynamics

Thermal Properties and Processes

The Electric Field Ii: Continuous Charge Distributions

Electric Potential

Capacitance

Electric Current and Direct-Current Circuits

The Magnetic Field

Sources of the Magnetic Field

Magnetic Induction

Alternating-Current Circuits

Maxwells Equations and Electromagnetic Waves

Properties of Light

Optical Images

Interference and Diffraction

Wave Particle Duality and Quantum Physics

Applications of the Schrodinger Equation

Atoms

Molecules

Solids and the Theory of Conduction

Relativity

Nuclear Physics

Elementary Particles and the Beginning of the Universe

Filters

Charges q₁ and q₂ exert repulsive forces of 10 N on each other.What is the repulsive force when their separation is decreased so that their final separation is 80% of their initial separation?

An oil droplet of mass 1.00 $\times$ 10^-14 kg loses an electron while it is in an electric field of 1.00 $\times$ 10⁶ N/C.The resulting change in the acceleration of the oil droplet is approximately

The Coulomb's force between a proton and an electron is 2.27 $\times$ 10³⁹ times greater than the gravitational force.If the two forces were equal,what should the size of the elementary charge be

An electric dipole p makes an angle of 30^$\circ$ with a uniform electric field of magnitude 300 N/C.If the torque on the dipole is 3.00 $\times$ 10^-12 N · m then calculate the magnitude of the dipole moment p.

A molecule of HCl has a dipole moment of 3.39 $\times$ 10^-30 C · m.If we assume full donation of the hydrogen electron to the chlorine,then calculate the distance between the charge centers.