Question 1

The electric field at point A is as shown.What must be the relation between charges q1 and q2?

Accepted Answer

A) q1 = q2 
B) q1 = -q2 
C) q1 = (2)1/2q2 
D) q1 = -(2)1/2q2 
E) It is not possible. 
A) q1 = q2 
B) q1 = -q2 
C) q1 = (2)1/2q2 
D) q1 = -(2)1/2q2 
E) It is not possible. B

Question 2

Electric field lines always point from

Accepted Answer

A) positive charges to positive charges. 
B) negative charges to negative charges. 
C) positive charges to negative charges. 
D) negative charges to positive charges. 
A) positive charges to positive charges. 
B) negative charges to negative charges. 
C) positive charges to negative charges. 
D) negative charges to positive charges. C

Question 3

The electrons in a particle beam each have a kinetic energy of 1.6 * 10-16 J.The magnitude of the electric field that would stop the electrons in a distance of 1 m is

Accepted Answer

A) 2000 N/C. 
B) 1000 N/C. 
C) 780 N/C. 
D) 620 N/C. 
E) 545 N/C. 
A) 2000 N/C. 
B) 1000 N/C. 
C) 780 N/C. 
D) 620 N/C. 
E) 545 N/C. B

Question 4

A thin glass rod is bent into a semicircle of radius R.A charge + Q is uniformly distributed along the upper half,and a charge -Q is uniformly distributed along the lower half,as shown in the figure.If Q = 10 nC and R = 10 cm,find the magnitude and direction of the electric field E (in component form)at point P,the center of the semicircle.

Accepted Answer

A) 3.61 * 104 N/C in + y direction 
B) 3.61 * 104 N/C in -y direction 
C) 1.15 * 104 N/C in + x direction 
D) 1.15 * 104 N/C in -y direction 
A) 3.61 * 104 N/C in + y direction 
B) 3.61 * 104 N/C in -y direction 
C) 1.15 * 104 N/C in + x direction 
D) 1.15 * 104 N/C in -y direction

Question 5

A small charge of -11 $\mu$C is in a constant vertical electric field.If the charge has a mass of 0.022 kg and its acceleration is -1.0 m/s2(in the negative y-direction),what is the value of the constant electric field? There is no gravity.

Accepted Answer

A) +1.32 * 103 N/C 
B) -1.32 * 103 N/C 
C) +2.00 * 103 N/C 
D) -2.00 * 103 N/C 
E) +2.42 * 103 N/C 
A) +1.32 * 103 N/C 
B) -1.32 * 103 N/C 
C) +2.00 * 103 N/C 
D) -2.00 * 103 N/C 
E) +2.42 * 103 N/C

Question 6

A cannon shoots 5.0-kg cannon ball that carries a charge of 3.0 Coulombs at some angle above horizontal ground in a region in which there is a uniform electric field E and gravitational acceleration is straight down,-9.8 m/s2 ŷ.If the ball travels half the horizontal distance before striking the ground that it would have if there were no electric field,what is the magnitude of the electric field?

Accepted Answer

A) + 16 N/C ŷ 
B) -16N/C ŷ 
C) + 49 N/C ŷ 
D) -49 N/C ŷ 
E) Cannot answer-the angle of launch is needed. 
A) + 16 N/C ŷ 
B) -16N/C ŷ 
C) + 49 N/C ŷ 
D) -49 N/C ŷ 
E) Cannot answer-the angle of launch is needed.

Question 7

In the opposite corners of a square there are two identical ions.Each has a charge of -e.The length of one side of he square is L.What is the magnitude of the net electric field caused by the two negative ions at both of the empty corners of the square?

Accepted Answer

A) ke/2L2 
B) ke/L2 
C)    ke/L2 
D) 2ke/L2 
A) ke/2L2 
B) ke/L2 
C)    ke/L2 
D) 2ke/L2

Question 8

A metal ball hangs from a string.An electric field of 15,000 N/C,pointing to the right,is then turned on.After the electric field is turned on,the ball hangs at a 25 degree angle away from the vertical.If the charge on the ball is 1.4 * 10-5 C,what is the mass of the ball?

Accepted Answer

A) 49 g 
B) 22 g 
C) 52 g 
D) 46 g 
E) 37 g 
A) 49 g 
B) 22 g 
C) 52 g 
D) 46 g 
E) 37 g

Question 9

A solid,insulating sphere of radius a = 2 cm has a total charge Q = 10 nC which is uniformly distributed.Using Gauss's Law determine the magnitude of the electric field at a point inside sphere which is 1 cm from its center.

Accepted Answer

A) 1.13 * 105 N/C 
B) 2.25 * 105 N/C 
C) 0 N/C 
D) 3.61 * 105 N/C 
A) 1.13 * 105 N/C 
B) 2.25 * 105 N/C 
C) 0 N/C 
D) 3.61 * 105 N/C

Question 10

A thin glass rod is bent into a semicircle of radius R.A charge + Q is uniformly distributed along the upper half,and a charge -Q is uniformly distributed along the lower half,as shown in the figure.If R = 10 cm and the electric field E at point P is 4.81 * 104 N/C in -y direction,what is the charge,Q? Point P is at the center of the semicircle.

Accepted Answer

A) 62 nC 
B) 10 nC 
C) 42 nC 
D) 27 nC 
E) 51 nC 
A) 62 nC 
B) 10 nC 
C) 42 nC 
D) 27 nC 
E) 51 nC

Question 11

An insulating solid sphere of radius a has a uniform volume charge density $\rho$ and total positive charge q.The strength of the electric field inside the sphere at a distance r from the center (r < a)is proportional to

Accepted Answer

A) a. 
B) r. 
C) 1/r2. 
D) 1/r3. 
E) 1/a2. 
A) a. 
B) r. 
C) 1/r2. 
D) 1/r3. 
E) 1/a2.

Question 12

A 3.5-C point charge sits in the center of a 1 m cube.What is the electric flux through one side of the cube?

Accepted Answer

A) 5.0 * 1010 Nm2/C 
B) 3.3 * 1010 Nm2/C 
C) 4.5 * 1010 Nm2/C 
D) 6.6 * 1010 Nm2/C 
E) 7.2 * 1010 Nm2/C 
A) 5.0 * 1010 Nm2/C 
B) 3.3 * 1010 Nm2/C 
C) 4.5 * 1010 Nm2/C 
D) 6.6 * 1010 Nm2/C 
E) 7.2 * 1010 Nm2/C

Question 13

A + 8.0-nC point charge is located in the center of a thick conducting spherical shell.The shell has an inner radius of 1.0 m,an outer radius of 1.2 m,and a charge of -3.0 nC.What is the magnitude of the electric field at r = 1.1 m?

Accepted Answer

A) 0 N/C 
B) 22 N/C 
C) 38 N/C 
D) 60 N/C 
E) 110 N/C 
A) 0 N/C 
B) 22 N/C 
C) 38 N/C 
D) 60 N/C 
E) 110 N/C

Question 14

A thin glass rod is bent into a semicircle of radius R.A charge + Q is uniformly distributed along the upper half,and a charge -Q is uniformly distributed along the lower half,as shown in the figure.If Q = 10 nC and the electric field E at point P is 5.85 * 104 N/C in -y direction,what is the radius of the semicircle,R? Point P is at the center of the semicircle.

Accepted Answer

A) 10 cm 
B) 9.0 cm 
C) 14 cm 
D) 16 cm 
E) 12 cm 
A) 10 cm 
B) 9.0 cm 
C) 14 cm 
D) 16 cm 
E) 12 cm

Question 15

A point charge of -1.4 $\mu$C is located at the center of a right cylinder.If the electric flux through one of the circular end caps is -2.4 * 104 Nm2/C,what is the flux through the cylindrical section between the end caps?

Accepted Answer

A) 1.1 * 105 Nm2/C 
B) -1.1 * 105 Nm2/C 
C) 1.3 * 105 Nm2/C 
D) -1.3* 105 Nm2/C 
E) More information is required to determine this flux. 
A) 1.1 * 105 Nm2/C 
B) -1.1 * 105 Nm2/C 
C) 1.3 * 105 Nm2/C 
D) -1.3* 105 Nm2/C 
E) More information is required to determine this flux.

Question 16

In which of the following situations is the magnitude of the electric field the strongest.

Accepted Answer

A) a point 1 m from a 1-C point charge 
B) a point 1 m along a perpendicular line from the center of a 1-m rod with a charge of 1-C 
C) a point 1 m along a perpendicular line from the center of a 1-m diameter disk of charge 1 C 
D) a point 1 m from the end of a 1m rod with a charge of 1 C along a line running longitudinal with the rod 
E) All of the choices have the same electric field. 
A) a point 1 m from a 1-C point charge 
B) a point 1 m along a perpendicular line from the center of a 1-m rod with a charge of 1-C 
C) a point 1 m along a perpendicular line from the center of a 1-m diameter disk of charge 1 C 
D) a point 1 m from the end of a 1m rod with a charge of 1 C along a line running longitudinal with the rod 
E) All of the choices have the same electric field.

Question 17

A + 5.0 C charge is located at the origin.A -13.0 C charge is placed at x = 1.0 m.At what finite location(s)on the x axis will the electric field be equal to zero?

Accepted Answer

A) in between the particles,closer to the positive particle 
B) in between the particles,closer to the negative particle 
C) not in between,but closer to the positive particle 
D) not in between,but closer to the negative particle 
E) It can never be zero. 
A) in between the particles,closer to the positive particle 
B) in between the particles,closer to the negative particle 
C) not in between,but closer to the positive particle 
D) not in between,but closer to the negative particle 
E) It can never be zero.

Question 18

A charge q1 = 1.0 $\mu$C is placed at the origin of an x-axis and another charge q2 = 2.0 $\mu$C is placed at position x = 10 cm.Find a point on the axis where the electric field due to these two charges is zero.

Accepted Answer

A) x = 2.6 cm 
B) x = -3.2 cm 
C) x = 4.2 cm 
D) x = -10.0 cm 
E) x = 5 cm 
A) x = 2.6 cm 
B) x = -3.2 cm 
C) x = 4.2 cm 
D) x = -10.0 cm 
E) x = 5 cm

Question 19

Which of the following surfaces have the largest total electric flux?

Accepted Answer

A) a sphere of radius 1 m with a 1-C charge placed inside at the center 
B) a sphere of radius 1 m with a 1-C charge placed inside but off-center 
C) a cylinder of radius 1 m and length 1 m with a 1-C charge placed inside 
D) a 1-m cube with a 1-C charge placed in the center 
E) a sphere of radius 1 m with a 2-C charge placed inside and a 1-C charge placed outside 
A) a sphere of radius 1 m with a 1-C charge placed inside at the center 
B) a sphere of radius 1 m with a 1-C charge placed inside but off-center 
C) a cylinder of radius 1 m and length 1 m with a 1-C charge placed inside 
D) a 1-m cube with a 1-C charge placed in the center 
E) a sphere of radius 1 m with a 2-C charge placed inside and a 1-C charge placed outside

Question 20

The electric field is zero at some point on a line that runs between the centers of two charged spheres.What can one say about this situation?

Accepted Answer

A) The charges on the two spheres are opposite in sign. 
B) The charges on the two spheres have the same sign. 
C) The point of interest is equidistant from the two spheres' centers. 
D) There is no such point on the line. 
E) None are correct. 
A) The charges on the two spheres are opposite in sign. 
B) The charges on the two spheres have the same sign. 
C) The point of interest is equidistant from the two spheres' centers. 
D) There is no such point on the line. 
E) None are correct.

Exam 22: Electric Fields and Gausss Law

The electric field at point A is as shown.What must be the relation between charges q1 and q2?

Electric field lines always point from

The electrons in a particle beam each have a kinetic energy of 1.6 * 10-16 J.The magnitude of the electric field that would stop the electrons in a distance of 1 m is

A small charge of -11 μ\muμ C is in a constant vertical electric field.If the charge has a mass of 0.022 kg and its acceleration is -1.0 m/s2(in the negative y-direction),what is the value of the constant electric field? There is no gravity.

In the opposite corners of a square there are two identical ions.Each has a charge of -e.The length of one side of he square is L.What is the magnitude of the net electric field caused by the two negative ions at both of the empty corners of the square?

A metal ball hangs from a string.An electric field of 15,000 N/C,pointing to the right,is then turned on.After the electric field is turned on,the ball hangs at a 25 degree angle away from the vertical.If the charge on the ball is 1.4 * 10-5 C,what is the mass of the ball?

A solid,insulating sphere of radius a = 2 cm has a total charge Q = 10 nC which is uniformly distributed.Using Gauss's Law determine the magnitude of the electric field at a point inside sphere which is 1 cm from its center.

An insulating solid sphere of radius a has a uniform volume charge density ρ\rhoρ and total positive charge q.The strength of the electric field inside the sphere at a distance r from the center (r < a)is proportional to

A 3.5-C point charge sits in the center of a 1 m cube.What is the electric flux through one side of the cube?

A + 8.0-nC point charge is located in the center of a thick conducting spherical shell.The shell has an inner radius of 1.0 m,an outer radius of 1.2 m,and a charge of -3.0 nC.What is the magnitude of the electric field at r = 1.1 m?

A point charge of -1.4 μ\muμ C is located at the center of a right cylinder.If the electric flux through one of the circular end caps is -2.4 * 104 Nm2/C,what is the flux through the cylindrical section between the end caps?

In which of the following situations is the magnitude of the electric field the strongest.

A + 5.0 C charge is located at the origin.A -13.0 C charge is placed at x = 1.0 m.At what finite location(s)on the x axis will the electric field be equal to zero?

A charge q1 = 1.0 μ\muμ C is placed at the origin of an x-axis and another charge q2 = 2.0 μ\muμ C is placed at position x = 10 cm.Find a point on the axis where the electric field due to these two charges is zero.

Which of the following surfaces have the largest total electric flux?

The electric field is zero at some point on a line that runs between the centers of two charged spheres.What can one say about this situation?

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The electric field at point A is as shown.What must be the relation between charges q₁ and q₂?

The electrons in a particle beam each have a kinetic energy of 1.6 * 10^-16 J.The magnitude of the electric field that would stop the electrons in a distance of 1 m is

A small charge of -11 $\mu$ C is in a constant vertical electric field.If the charge has a mass of 0.022 kg and its acceleration is -1.0 m/s²(in the negative y-direction),what is the value of the constant electric field? There is no gravity.

A metal ball hangs from a string.An electric field of 15,000 N/C,pointing to the right,is then turned on.After the electric field is turned on,the ball hangs at a 25 degree angle away from the vertical.If the charge on the ball is 1.4 * 10^-5 C,what is the mass of the ball?

An insulating solid sphere of radius a has a uniform volume charge density $\rho$ and total positive charge q.The strength of the electric field inside the sphere at a distance r from the center (r < a)is proportional to

A point charge of -1.4 $\mu$ C is located at the center of a right cylinder.If the electric flux through one of the circular end caps is -2.4 * 10⁴ Nm²/C,what is the flux through the cylindrical section between the end caps?

A charge q₁ = 1.0 $\mu$ C is placed at the origin of an x-axis and another charge q₂ = 2.0 $\mu$ C is placed at position x = 10 cm.Find a point on the axis where the electric field due to these two charges is zero.