Question 1

A wire contains a steady current of 2 A.The number of electrons that pass a cross section in 2 s is:

Accepted Answer

A) 2 
B) 4 
C) 6.3 *1018 
D) 1.3 * 1019 
E) 2.5 *1019 
A) 2 
B) 4 
C) 6.3 *1018 
D) 1.3 * 1019 
E) 2.5 *1019

Question 2

Two uncharged metal spheres, L and M, are in contact.A negatively charged rod is brought close to L, but not touching it, as shown.The two spheres are slightly separated and the rod is then withdrawn.As a result:

Accepted Answer

A) both spheres are neutral 
B) both spheres are positive 
C) both spheres are negative 
D) L is negative and M is positive 
E) L is positive and M is negative 
A) both spheres are neutral 
B) both spheres are positive 
C) both spheres are negative 
D) L is negative and M is positive 
E) L is positive and M is negative

Question 3

To make an uncharged object have a positive charge:

Accepted Answer

A) remove some neutrons 
B) add some neutrons 
C) add some electrons 
D) remove some electrons 
E) heat it to cause a change of phase 
A) remove some neutrons 
B) add some neutrons 
C) add some electrons 
D) remove some electrons 
E) heat it to cause a change of phase

Question 4

Is it ever possible for the following process to occur? γ → e+ + e- + e+

Accepted Answer

A) Yes, it is. 
B) No, this process does not conserve energy. 
C) No, this process does not conserve momentum. 
D) No, this process does not conserve mass. 
E) No, this process does not conserve electric charge. 
A) Yes, it is. 
B) No, this process does not conserve energy. 
C) No, this process does not conserve momentum. 
D) No, this process does not conserve mass. 
E) No, this process does not conserve electric charge.

Question 5

The diagram shows a pair of highly charged plastic cubes that attract each other.   Cube 3 is a conductor and is uncharged.Which of the following illustrates the forces between cubes1 and 3 and between cubes 2 and 3?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 6

Two electrons (e1 and e2)and a proton (p)lie on a straight line, as shown.The directions of the force of e2 on e1, the force of p on e1, and the total force on e1, respectively, are:

Accepted Answer

A) "$\rightarrow$, $\leftarrow$, $\rightarrow$" 
B) "$\leftarrow$, $\rightarrow$, $\rightarrow$" 
C) "$\rightarrow$, $\leftarrow$, $\leftarrow$" 
D) "$\leftarrow$, $\rightarrow$, $\leftarrow$" 
E) "$\leftarrow$, $\leftarrow$, $\leftarrow$" 
A) "$\rightarrow$, $\leftarrow$, $\rightarrow$" 
B) "$\leftarrow$, $\rightarrow$, $\rightarrow$" 
C) "$\rightarrow$, $\leftarrow$, $\leftarrow$" 
D) "$\leftarrow$, $\rightarrow$, $\leftarrow$" 
E) "$\leftarrow$, $\leftarrow$, $\leftarrow$"

Question 7

Charge is distributed uniformly on the surface of a spherical nonconducting shell.A point particle with charge q is inside.The electrical force on the particle q is least when:

Accepted Answer

A) it is near the inside surface of the shell 
B) it is at the center of the shell 
C) it is halfway between the shell center and the inside surface 
D) it is near, but not at, the center of the shell 
E) all of the above (the force is zero everywhere inside) 
A) it is near the inside surface of the shell 
B) it is at the center of the shell 
C) it is halfway between the shell center and the inside surface 
D) it is near, but not at, the center of the shell 
E) all of the above (the force is zero everywhere inside)

Question 8

The magnitude of the total negative charge on the electrons in 1 mol of helium (atomic number 2, atomic mass 4)is:

Accepted Answer

A) 4.8 * 104 C 
B) 9.6 *104 C 
C) 1.9 *105 C 
D) 3.8 * 105 C 
E) 7.7 *105 C 
A) 4.8 * 104 C 
B) 9.6 *104 C 
C) 1.9 *105 C 
D) 3.8 * 105 C 
E) 7.7 *105 C

Question 9

Two particles, each with charge Q, and a third particle, with a charge q, are placed at the vertices of an equilateral triangle as shown.The total force on the particle with charge q is:

Accepted Answer

A) Parallel to the left side of the triangle 
B) Parallel to the right side of the triangle 
C) Parallel to the bottom side of the triangle 
D) perpendicular to the bottom side of the triangle 
E) perpendicular to the left side of the triangle 
A) Parallel to the left side of the triangle 
B) Parallel to the right side of the triangle 
C) Parallel to the bottom side of the triangle 
D) perpendicular to the bottom side of the triangle 
E) perpendicular to the left side of the triangle

Question 10

Two small charged objects repel each other with a force F when separated by a distance d.If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes:

Accepted Answer

A) F/16 
B) F/8 
C) F/4 
D) F/2 
E) F 
A) F/16 
B) F/8 
C) F/4 
D) F/2 
E) F

Question 11

A particle with a charge of 5 *10-6 C and a mass of 20 g moves uniformly with a speed of 7 m/s in a circular orbit around a stationary particle with a charge of -5 * 10-6 C.The radius of the orbit is:

Accepted Answer

A) 0 m 
B) 0.23 m 
C) 0.62 m 
D) 1.6 m 
E) 4.4 m 
A) 0 m 
B) 0.23 m 
C) 0.62 m 
D) 1.6 m 
E) 4.4 m

Question 12

The magnitude of the total negative charge on the electrons in 1 kg of helium (atomic number 2, atomic mass 4)is:

Accepted Answer

A) 48 C 
B) 2.4 * 107 C 
C) 4.8* 107 C 
D) 9.6 *107 C 
E) 1.9 * 108 C 
A) 48 C 
B) 2.4 * 107 C 
C) 4.8* 107 C 
D) 9.6 *107 C 
E) 1.9 * 108 C

Question 13

Two identical conducting spheres A and B carry equal charge and exert electrostatic forces of magnitude F on each other.They are separated by a distance much larger than their diameters.A third identical conducting sphere C is uncharged.Sphere C is first touched to A, then to B, and finally removed.As a result, the electrostatic force between A and B becomes:

Accepted Answer

A) F/2 
B) F/4 
C) 3F/8 
D) F/16 
E) 0 
A) F/2 
B) F/4 
C) 3F/8 
D) F/16 
E) 0

Question 14

A positively charged insulating rod is brought close to an object that is suspended by a string.If the object is repelled away from the rod we can conclude:

Accepted Answer

A) the object is positively charged 
B) the object is negatively charged 
C) the object is an insulator 
D) the object is a conductor 
E) none of the above 
A) the object is positively charged 
B) the object is negatively charged 
C) the object is an insulator 
D) the object is a conductor 
E) none of the above

Question 15

Two identical charges, 2.0 m apart, exert forces of magnitude 4.0 N on each other.The value of either charge is:

Accepted Answer

A) 1.8 * 10-9 C 
B) 2.1 *10-5 C 
C) 4.2 *10-5 C 
D) 1.9 *105 C 
E) 3.8 * 105 C 
A) 1.8 * 10-9 C 
B) 2.1 *10-5 C 
C) 4.2 *10-5 C 
D) 1.9 *105 C 
E) 3.8 * 105 C

Question 16

Particle 1 with charge q1, and particle 2, with a charge q2, are on the x axis, with particle 1 at x = a with and particle 2 at x = -2a.For the net force on a third charged particle, at the origin to be zero q1 and q2 must be related by q2=:

Accepted Answer

A) 2q1 
B) 4q1 
C) -2q1 
D) -4q1 
E) -q1/4 
A) 2q1 
B) 4q1 
C) -2q1 
D) -4q1 
E) -q1/4

Question 17

A particle with charge 2°C is placed at the origin.An identical particle, with the same charge, is placed 2 m from the origin on the x axis, and a third identical particle, with the same charge, is placed 2 m from the origin on the y axis.The magnitude of the force on the particle at the origin is:

Accepted Answer

A) 9.0 * 10-3 N 
B) 6.4* 10-3 N 
C) 1.3* 10-2 N 
D) 1.8 *10-2 N 
E) 3.6 *10-2 N 
A) 9.0 * 10-3 N 
B) 6.4* 10-3 N 
C) 1.3* 10-2 N 
D) 1.8 *10-2 N 
E) 3.6 *10-2 N

Question 18

In the Rutherford model of the hydrogen atom, a proton (mass M, charge Q)is the nucleus and an electron (mass m, charge q)moves around the proton in a circle of radius r.Let k denote the Coulomb force constant (1/4$\pi$ )and G the universal gravitational constant.The ratio of the electrostatic force to the gravitational force between electron and proton is:

Accepted Answer

A) kQq/GMmr2 
B) GQq/kMm 
C) kMm/GQq 
D) GMm/kQq 
E) kQq/GMm 
A) kQq/GMmr2 
B) GQq/kMm 
C) kMm/GQq 
D) GMm/kQq 
E) kQq/GMm

Question 19

A nucleus of carbon 14 has 6 protons and 8 neutrons.The atomic number and mass number of carbon 14 are, respectively,

Accepted Answer

A) 6 and 8 
B) 6 and 14 
C) 8 and 14 
D) 14 and 20 
E) 14 and 22 
A) 6 and 8 
B) 6 and 14 
C) 8 and 14 
D) 14 and 20 
E) 14 and 22

Question 20

A charged insulator can be discharged by passing it just above a flame.This is because the flame:

Accepted Answer

A) warms it 
B) dries it 
C) contains carbon dioxide 
D) contains ions 
E) contains more rapidly moving atoms 
A) warms it 
B) dries it 
C) contains carbon dioxide 
D) contains ions 
E) contains more rapidly moving atoms

Exam 21: Coulombs Law

A wire contains a steady current of 2 A.The number of electrons that pass a cross section in 2 s is:

Two uncharged metal spheres, L and M, are in contact.A negatively charged rod is brought close to L, but not touching it, as shown.The two spheres are slightly separated and the rod is then withdrawn.As a result:

To make an uncharged object have a positive charge:

Is it ever possible for the following process to occur? γ → e+ + e- + e+

The diagram shows a pair of highly charged plastic cubes that attract each other. Cube 3 is a conductor and is uncharged.Which of the following illustrates the forces between cubes1 and 3 and between cubes 2 and 3?

Two electrons (e1 and e2)and a proton (p)lie on a straight line, as shown.The directions of the force of e2 on e1, the force of p on e1, and the total force on e1, respectively, are:

Charge is distributed uniformly on the surface of a spherical nonconducting shell.A point particle with charge q is inside.The electrical force on the particle q is least when:

The magnitude of the total negative charge on the electrons in 1 mol of helium (atomic number 2, atomic mass 4)is:

Two particles, each with charge Q, and a third particle, with a charge q, are placed at the vertices of an equilateral triangle as shown.The total force on the particle with charge q is:

Two small charged objects repel each other with a force F when separated by a distance d.If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes:

A particle with a charge of 5 *10-6 C and a mass of 20 g moves uniformly with a speed of 7 m/s in a circular orbit around a stationary particle with a charge of -5 * 10-6 C.The radius of the orbit is:

The magnitude of the total negative charge on the electrons in 1 kg of helium (atomic number 2, atomic mass 4)is:

A positively charged insulating rod is brought close to an object that is suspended by a string.If the object is repelled away from the rod we can conclude:

Two identical charges, 2.0 m apart, exert forces of magnitude 4.0 N on each other.The value of either charge is:

Particle 1 with charge q1, and particle 2, with a charge q2, are on the x axis, with particle 1 at x = a with and particle 2 at x = -2a.For the net force on a third charged particle, at the origin to be zero q1 and q2 must be related by q2=:

A nucleus of carbon 14 has 6 protons and 8 neutrons.The atomic number and mass number of carbon 14 are, respectively,

A charged insulator can be discharged by passing it just above a flame.This is because the flame:

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Filters

Is it ever possible for the following process to occur? γ → e⁺+ e^- + e⁺

Two electrons (e₁ and e₂)and a proton (p)lie on a straight line, as shown.The directions of the force of e₂ on e₁, the force of p on e₁, and the total force on e₁, respectively, are:

A particle with a charge of 5 10^-6 C and a mass of 20 g moves uniformly with a speed of 7 m/s in a circular orbit around a stationary particle with a charge of -5 10^-6 C.The radius of the orbit is:

Particle 1 with charge q₁, and particle 2, with a charge q_2,are on the x axis, with particle 1 at x = a with and particle 2 at x = -2a.For the net force on a third charged particle, at the origin to be zero q₁ and q₂ must be related by q₂=: