Question 1

Consider Gauss law:   .Which of the following is true?

Accepted Answer

A)    must be the electric field due to the enclosed charge 
B) If q = 0 then   everywhere on the Gaussian surface 
C) If the three particles inside have charges of +q, +q and -2q, then the integral is zero 
D) On the surface   is everywhere parallel to
  
E) If a charge is placed outside the surface, then it cannot affect   at any point on the surface 
A)    must be the electric field due to the enclosed charge 
B) If q = 0 then   everywhere on the Gaussian surface 
C) If the three particles inside have charges of +q, +q and -2q, then the integral is zero 
D) On the surface   is everywhere parallel to
  
E) If a charge is placed outside the surface, then it cannot affect   at any point on the surface

Question 2

A 300-N/C uniform electric field points perpendicularly toward the left face of a large neutral conducting sheet.The area charge density on the left and right faces, respectively, are:

Accepted Answer

A) -2.7 *10-9 C/m2; +2.7 * 10-9 C/m 2 
B) +2.7 * 10-9 C/m2; -2.7 * 10-9 C/m 2 
C) -5.3 *10-9 C/m2; +5.3 * 10-9 C/m 2 
D) +5.3 * 10-9 C/m2; -5.3 * 10-9 C/m 2 
E) 0 C/m2; 0 C/m2 
A) -2.7 *10-9 C/m2; +2.7 * 10-9 C/m 2 
B) +2.7 * 10-9 C/m2; -2.7 * 10-9 C/m 2 
C) -5.3 *10-9 C/m2; +5.3 * 10-9 C/m 2 
D) +5.3 * 10-9 C/m2; -5.3 * 10-9 C/m 2 
E) 0 C/m2; 0 C/m2

Question 3

Positive charge Q is placed on a conducting spherical shell with inner radius R1 and outer radius R2.A particle with charge q is placed at the center of the cavity.The magnitude of the electric field at a point in the cavity, a distance r from the center, is:

Accepted Answer

A)    
B)    
C) q/4 $\pi$$\varepsilon$0r2 
D) (q + Q)/4 $\pi$$\varepsilon$0r2 
E)    
A)    
B)    
C) q/4 $\pi$$\varepsilon$0r2 
D) (q + Q)/4 $\pi$$\varepsilon$0r2 
E)

Question 4

10 C of charge are placed on a spherical conducting shell.A particle with a charge of -3 C is placed at the center of the cavity.The net charge on the inner surface of the shell is:

Accepted Answer

A) -7 C 
B) -3 C 
C) 0 C 
D) +3 C 
E) +7 C 
A) -7 C 
B) -3 C 
C) 0 C 
D) +3 C 
E) +7 C

Question 5

Positive charge Q is placed on a conducting spherical shell with inner radius R1 and outer radius R2.A point charge q is placed at the center of the cavity.The magnitude of the electric field at a point in the interior of the conductor a distance r from the center is:

Accepted Answer

A) 0 
B)    
C)    
D) q/4  $\pi$  r2 
E) Q/4 $\pi$  r2 
A) 0 
B)    
C)    
D) q/4  $\pi$  r2 
E) Q/4 $\pi$  r2

Question 6

A particle with charge 5.0 ° C is placed at the corner of a cube.The total electric flux through all sides of the cube is:

Accepted Answer

A) 0 N.m2/C 
B) 7.1 * 104 N.m2/C 
C) 9.4 * 104 N.m2/C 
D) 1.4 * 105 N.m2/C 
E) 5.6 * 105 N.m2/C 
A) 0 N.m2/C 
B) 7.1 * 104 N.m2/C 
C) 9.4 * 104 N.m2/C 
D) 1.4 * 105 N.m2/C 
E) 5.6 * 105 N.m2/C

Question 7

A point particle with charge q is at the center of a Gaussian surface in the form of a cube.The electric flux through any one face of the cube is:

Accepted Answer

A) q/F1F1F1S  
B) q/4F1F1F1S  
C) q/4F1F1F1S . 
D) q/6F1F1F1S  
E) q/16F1F1F1S  
A) q/F1F1F1S  
B) q/4F1F1F1S  
C) q/4F1F1F1S . 
D) q/6F1F1F1S  
E) q/16F1F1F1S

Question 8

When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N.m2/C.When the paper is turned 25 °  with respect to the field the flux through it is:

Accepted Answer

A) 0 N.m2/C 
B) 11 N.m2/C 
C) 12 N.m2/C 
D) 23 N.m2/C 
E) 25 N.m2/C 
A) 0 N.m2/C 
B) 11 N.m2/C 
C) 12 N.m2/C 
D) 23 N.m2/C 
E) 25 N.m2/C

Question 9

A physics instructor in an anteroom charges an electrostatic generator to 25 *C, then carries it into the lecture hall.The net electric flux through the lecture hall walls is:

Accepted Answer

A) 0 N.m2/C 
B) 25 * 10-6 N.m2/C 
C) 2.2 *105 N.m2/C 
D) 2.8 *106 N.m2/C 
E) can't tell unless the lecture hall dimensions are given 
A) 0 N.m2/C 
B) 25 * 10-6 N.m2/C 
C) 2.2 *105 N.m2/C 
D) 2.8 *106 N.m2/C 
E) can't tell unless the lecture hall dimensions are given

Question 10

The table below gives the electric flux through the ends and round surfaces of four Gaussian surfaces in the form of cylinders.Rank the cylinders according to the charge inside, from the most negative to the most positive.

Accepted Answer

A) 1, 2, 3, 4 
B) 4, 3, 2, 1 
C) 3, 4, 2, 1 
D) 3, 1, 4, 2 
E) 4, 3, 1, 2 
A) 1, 2, 3, 4 
B) 4, 3, 2, 1 
C) 3, 4, 2, 1 
D) 3, 1, 4, 2 
E) 4, 3, 1, 2

Question 11

The area vector for a flat surface:

Accepted Answer

A) is parallel to the surface and has a magnitude equal to the length of a side of the surface. 
B) is perpendicular to the surface and has a magnitude equal to the length of a side of the surface. 
C) is parallel to the surface and has a magnitude equal to the area of the surface. 
D) is perpendicular to the surface and has a magnitude equal to the area of the surface. 
E) none of the above. 
A) is parallel to the surface and has a magnitude equal to the length of a side of the surface. 
B) is perpendicular to the surface and has a magnitude equal to the length of a side of the surface. 
C) is parallel to the surface and has a magnitude equal to the area of the surface. 
D) is perpendicular to the surface and has a magnitude equal to the area of the surface. 
E) none of the above.

Question 12

A long line of charge with   charge per unit length runs along the cylindrical axis of a cylindrical conducting shell which carries a charge per unit length of  $\lambda$ c.The charge per unit length on the inner and outer surfaces of the shell, respectively are:

Accepted Answer

A)  and $\lambda$c 
B) -  and $\lambda$c + -  
C) -  and $\lambda$c -    
D)   + $\lambda$c and $\lambda$c -   
E)   - $\lambda$c and $\lambda$c +   
A)  and $\lambda$c 
B) -  and $\lambda$c + -  
C) -  and $\lambda$c -    
D)   + $\lambda$c and $\lambda$c -   
E)   - $\lambda$c and $\lambda$c +

Question 13

To calculate the flux through a curved surface,

Accepted Answer

A) the area vector has to be perpendicular to the surface somewhere 
B) you must divide the surface into pieces that are tiny enough to be almost flat 
C) the surface must be spherical 
D) the surface cannot be curved very much; then you can treat it as though it were flat 
E) actually the flux through a curved surface cannot be calculated. 
A) the area vector has to be perpendicular to the surface somewhere 
B) you must divide the surface into pieces that are tiny enough to be almost flat 
C) the surface must be spherical 
D) the surface cannot be curved very much; then you can treat it as though it were flat 
E) actually the flux through a curved surface cannot be calculated.

Question 14

Which statement is correct?

Accepted Answer

A) The flux through a closed surface is always positive. 
B) The flux through a closed surface is always negative. 
C) The sign of the flux through a closed surface depends on an arbitrary choice of sign for the surface vector. 
D) Inward flux through a closed surface is negative and outward flux is positive. 
E) Inward flux through a closed surface is positive and outward flux is negative. 
A) The flux through a closed surface is always positive. 
B) The flux through a closed surface is always negative. 
C) The sign of the flux through a closed surface depends on an arbitrary choice of sign for the surface vector. 
D) Inward flux through a closed surface is negative and outward flux is positive. 
E) Inward flux through a closed surface is positive and outward flux is negative.

Question 15

Choose the INCORRECT statement:

Accepted Answer

A) Gauss' law can be derived from Coulomb's law 
B) Gauss' law states that the net number of lines crossing any closed surface in an outward direction is proportional to the net charge enclosed within the surface 
C) Coulomb's law can be derived from Gauss' law and symmetry 
D) Gauss' law applies to a closed surface of any shape 
E) According to Gauss' law, if a closed surface encloses no charge, then the electric field must vanish everywhere on the surface 
A) Gauss' law can be derived from Coulomb's law 
B) Gauss' law states that the net number of lines crossing any closed surface in an outward direction is proportional to the net charge enclosed within the surface 
C) Coulomb's law can be derived from Gauss' law and symmetry 
D) Gauss' law applies to a closed surface of any shape 
E) According to Gauss' law, if a closed surface encloses no charge, then the electric field must vanish everywhere on the surface

Question 16

Positive charge Q is distributed uniformly throughout an insulating sphere of radius R, centered at the origin.A particle with a positive charge Q is placed at x = 2R on the x axis.The magnitude of the electric field at x = R/2 on the x axis is:

Accepted Answer

A) Q/72 $\pi$  R2 
B) Q/8 $\pi$  R2 
C) 7Q/18 $\pi$  R2 
D) 11Q/18 $\pi$  R2 
E) none of these 
A) Q/72 $\pi$  R2 
B) Q/8 $\pi$  R2 
C) 7Q/18 $\pi$  R2 
D) 11Q/18 $\pi$  R2 
E) none of these

Question 17

Gauss's law:

Accepted Answer

A) can always be used to calculate the electric field. 
B) relates the electric field throughout space to the charges distributed through that space. 
C) only applies to point charges. 
D) relates the electric field at points on a closed surface to the net charge enclosed by that surface. 
E) relates the surface charge density to the electric field. 
A) can always be used to calculate the electric field. 
B) relates the electric field throughout space to the charges distributed through that space. 
C) only applies to point charges. 
D) relates the electric field at points on a closed surface to the net charge enclosed by that surface. 
E) relates the surface charge density to the electric field.

Question 18

A closed cylinder with a 0.15-m radius ends is in a uniform electric field of 300 N/C, perpendicular to the ends.The total flux through the cylinder is:

Accepted Answer

A) 0 N.m2/C 
B) 4.2 N.m2/C 
C) 21 N.m2/C 
D) 280 N.m2/C 
E) can't tell without knowing the length of the cylinder 
A) 0 N.m2/C 
B) 4.2 N.m2/C 
C) 21 N.m2/C 
D) 280 N.m2/C 
E) can't tell without knowing the length of the cylinder

Question 19

Two large insulating parallel plates carry charge of equal magnitude, one positive and the other negative, that is distributed uniformly over their inner surfaces.Rank the points 1 through 5 according to the magnitude of the electric field at the points, least to greatest.

Accepted Answer

A) 1, 2, 3, 4, 5 
B) 5, 4, 3, 2, 1 
C) 1 and 4 and 5 tie, then 2 and 3 tie 
D) 2 and 3 tie, then 1 and 4 tie, then 5 
E) 2 and 3 tie, then 1 and 4 and 5 tie 
A) 1, 2, 3, 4, 5 
B) 5, 4, 3, 2, 1 
C) 1 and 4 and 5 tie, then 2 and 3 tie 
D) 2 and 3 tie, then 1 and 4 tie, then 5 
E) 2 and 3 tie, then 1 and 4 and 5 tie

Question 20

A conducting sphere of radius 0.01 m has a charge of 1.0 *10-9 C deposited on it.The magnitude of the electric field just outside the surface of the sphere is:

Accepted Answer

A) 0 N/C 
B) 450 N/C 
C) 900 N/C 
D) 4500 N/C 
E) 90,000 N/C 
A) 0 N/C 
B) 450 N/C 
C) 900 N/C 
D) 4500 N/C 
E) 90,000 N/C

Exam 23: Gauss Law

Consider Gauss law: .Which of the following is true?

A 300-N/C uniform electric field points perpendicularly toward the left face of a large neutral conducting sheet.The area charge density on the left and right faces, respectively, are:

Positive charge Q is placed on a conducting spherical shell with inner radius R1 and outer radius R2.A particle with charge q is placed at the center of the cavity.The magnitude of the electric field at a point in the cavity, a distance r from the center, is:

10 C of charge are placed on a spherical conducting shell.A particle with a charge of -3 C is placed at the center of the cavity.The net charge on the inner surface of the shell is:

Positive charge Q is placed on a conducting spherical shell with inner radius R1 and outer radius R2.A point charge q is placed at the center of the cavity.The magnitude of the electric field at a point in the interior of the conductor a distance r from the center is:

A particle with charge 5.0 ° C is placed at the corner of a cube.The total electric flux through all sides of the cube is:

A point particle with charge q is at the center of a Gaussian surface in the form of a cube.The electric flux through any one face of the cube is:

When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N.m2/C.When the paper is turned 25 ° with respect to the field the flux through it is:

A physics instructor in an anteroom charges an electrostatic generator to 25 *C, then carries it into the lecture hall.The net electric flux through the lecture hall walls is:

The table below gives the electric flux through the ends and round surfaces of four Gaussian surfaces in the form of cylinders.Rank the cylinders according to the charge inside, from the most negative to the most positive.

The area vector for a flat surface:

A long line of charge with charge per unit length runs along the cylindrical axis of a cylindrical conducting shell which carries a charge per unit length of λ\lambdaλ c.The charge per unit length on the inner and outer surfaces of the shell, respectively are:

To calculate the flux through a curved surface,

Which statement is correct?

Choose the INCORRECT statement:

Positive charge Q is distributed uniformly throughout an insulating sphere of radius R, centered at the origin.A particle with a positive charge Q is placed at x = 2R on the x axis.The magnitude of the electric field at x = R/2 on the x axis is:

Gauss's law:

A closed cylinder with a 0.15-m radius ends is in a uniform electric field of 300 N/C, perpendicular to the ends.The total flux through the cylinder is:

Two large insulating parallel plates carry charge of equal magnitude, one positive and the other negative, that is distributed uniformly over their inner surfaces.Rank the points 1 through 5 according to the magnitude of the electric field at the points, least to greatest.

A conducting sphere of radius 0.01 m has a charge of 1.0 *10-9 C deposited on it.The magnitude of the electric field just outside the surface of the sphere is:

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Positive charge Q is placed on a conducting spherical shell with inner radius R₁ and outer radius R₂.A particle with charge q is placed at the center of the cavity.The magnitude of the electric field at a point in the cavity, a distance r from the center, is:

Positive charge Q is placed on a conducting spherical shell with inner radius R₁ and outer radius R₂.A point charge q is placed at the center of the cavity.The magnitude of the electric field at a point in the interior of the conductor a distance r from the center is:

When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N.m²/C.When the paper is turned 25 ° with respect to the field the flux through it is:

A long line of charge with charge per unit length runs along the cylindrical axis of a cylindrical conducting shell which carries a charge per unit length of $\lambda$ _c.The charge per unit length on the inner and outer surfaces of the shell, respectively are:

A conducting sphere of radius 0.01 m has a charge of 1.0 *10^-9 C deposited on it.The magnitude of the electric field just outside the surface of the sphere is: