Question 1

Charge Q is distributed uniformly throughout an insulating sphere of radius R.The magnitude of the electric field at a point R/2 from the center is:

Accepted Answer

A) Q/4  $\pi$  R2 
B) Q/ $\pi$  R2 
C) 3Q/4  $\pi$  R2 
D) Q/8  $\pi$  R2 
E) none of these 
A) Q/4  $\pi$  R2 
B) Q/ $\pi$  R2 
C) 3Q/4  $\pi$  R2 
D) Q/8  $\pi$  R2 
E) none of these D

Question 2

A point charge is placed at the center of a spherical Gaussian surface.The electric flux $\phi$ E is changed if:

Accepted Answer

A) the sphere is replaced by a cube of the same volume 
B) the sphere is replaced by a cube of one-tenth the volume 
C) the point charge is moved off center (but still inside the original sphere) 
D) the point charge is moved to just outside the sphere 
E) a second point charge is placed just outside the sphere 
A) the sphere is replaced by a cube of the same volume 
B) the sphere is replaced by a cube of one-tenth the volume 
C) the point charge is moved off center (but still inside the original sphere) 
D) the point charge is moved to just outside the sphere 
E) a second point charge is placed just outside the sphere D

Question 3

The electric flux Φ through a surface:

Accepted Answer

A) is the amount of electric field piercing the surface. 
B) is the electric field multiplied by the area. 
C) does not depend on the area involved. 
D) is the line integral of the electric field around the edge of the surface. 
E) is the amount of electric field skimming along the surface. 
A) is the amount of electric field piercing the surface. 
B) is the electric field multiplied by the area. 
C) does not depend on the area involved. 
D) is the line integral of the electric field around the edge of the surface. 
E) is the amount of electric field skimming along the surface. A

Question 4

A particle with charge +Q is placed outside a large neutral conducting sheet.At any point in the interior of the sheet the electric field produced by charges on the surface is directed:

Accepted Answer

A) toward the surface 
B) away from the surface 
C) toward Q 
D) away from Q 
E) none of the above 
A) toward the surface 
B) away from the surface 
C) toward Q 
D) away from Q 
E) none of the above

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 outside the shell, a distance r from the center, is:

Accepted Answer

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

Question 6

Charge is distributed uniformly on the surface of a large flat plate.The electric field 2 cm from the plate is 30 N/C.The electric field 4 cm from the plate is:

Accepted Answer

A) 120 N/C 
B) 60 N/C 
C) 30 N/C 
D) 15 N/C 
E) 7.5 N/C 
A) 120 N/C 
B) 60 N/C 
C) 30 N/C 
D) 15 N/C 
E) 7.5 N/C

Question 7

A solid insulating sphere of radius R contains a positive charge that is distributed with a volume charge density that does not depend on angle but does increase linearly with distance from the sphere center.Which of the graphs below correctly gives the magnitude E of the electric field as a function of the distance r from the center of the sphere?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E 
A) A 
B) B 
C) C 
D) D 
E) E

Question 8

A spherical conducting shell has charge Q.A particle with charge q is placed at the center of the cavity.The charge on the inner surface of the shell and the charge on the outer surface of the shell, respectively, are:

Accepted Answer

A) 0, Q 
B) q, Q - q 
C) Q, 0 
D) -q, Q + q 
E) -q, 0 
A) 0, Q 
B) q, Q - q 
C) Q, 0 
D) -q, Q + q 
E) -q, 0

Question 9

A hollow conductor is positively charged.A small uncharged metal ball is lowered by a silk thread through a small opening in the top of the conductor and allowed to touch its inner surface.After the ball is removed, it will have:

Accepted Answer

A) a positive charge 
B) a negative charge 
C) no appreciable charge 
D) a charge whose sign depends on what part of the inner surface it touched 
E) a charge whose sign depends on where the small hole is located in the conductor 
A) a positive charge 
B) a negative charge 
C) no appreciable charge 
D) a charge whose sign depends on what part of the inner surface it touched 
E) a charge whose sign depends on where the small hole is located in the conductor

Question 10

Charge Q is distributed uniformly throughout a spherical insulating shell.The net electric flux through the outer surface of the shell is:

Accepted Answer

A) 0 
B) Q/   
C) 2Q/   
D) Q/4   
E) Q/2 $\pi$   
A) 0 
B) Q/   
C) 2Q/   
D) Q/4   
E) Q/2 $\pi$

Question 11

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 force on the charge q is:

Accepted Answer

A)    
B)    
C)    
D)    
E) 0 
A)    
B)    
C)    
D)    
E) 0

Question 12

Two large insulating parallel plates carry positive charge of equal magnitude 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 13

Charge Q is distributed uniformly throughout a spherical insulating shell.The net electric flux through the inner surface of the shell is:

Accepted Answer

A) 0 
B) Q/   
C) 2Q/   
D) Q/4 $\pi$   
E) Q/2 $\pi$   
A) 0 
B) Q/   
C) 2Q/   
D) Q/4 $\pi$   
E) Q/2 $\pi$

Question 14

Charge is distributed uniformly along a long straight wire.The electric field 2 cm from the wire is 20 N/C.The electric field 4 cm from the wire is:

Accepted Answer

A) 120 N/C 
B) 80 N/C 
C) 40 N/C 
D) 10 N/C 
E) 5 N/C 
A) 120 N/C 
B) 80 N/C 
C) 40 N/C 
D) 10 N/C 
E) 5 N/C

Question 15

A 3.5-cm radius hemisphere contains a total charge of 6.6 *10-7 C.The flux through the rounded portion of the surface is 9.8 *104 N.m2/C.The flux through the flat base is:

Accepted Answer

A) 0 N.m2/C 
B) +2.3 *104 N.m2/C 
C) -2.3 *104 N.m2/C 
D) -9.8 * 104 N.m2/C 
E) +9.8 *104 N.m2/C 
A) 0 N.m2/C 
B) +2.3 *104 N.m2/C 
C) -2.3 *104 N.m2/C 
D) -9.8 * 104 N.m2/C 
E) +9.8 *104 N.m2/C

Question 16

Two large conducting 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 17

A cylindrical wastepaper basket with a 0.15-m radius opening is in a uniform electric field of 300 N/C, perpendicular to the opening.The total flux through the sides and bottom 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 areas of the sides and bottom 
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 areas of the sides and bottom

Question 18

Positive charge Q is placed on a conducting spherical shell with inner radius R1 and outer radius R2.The electric field at a point r 1 is:

Accepted Answer

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

Question 19

A point particle with charge q is placed inside a cube but not at its center.The electric flux through any one side of the cube:

Accepted Answer

A) is zero 
B) is q/F1F1F1S  
C) is q/4F1F1F1S  
D) is q/6F1F1F1S  
E) cannot be computed using Gauss' law 
A) is zero 
B) is q/F1F1F1S  
C) is q/4F1F1F1S  
D) is q/6F1F1F1S  
E) cannot be computed using Gauss' law

Question 20

Which of the following graphs represents the magnitude of the electric field as a function of the distance from the center of a solid charged conducting sphere of radius R?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) E 
A) A 
B) B 
C) C 
D) D 
E) E

Exam 23: Gauss Law

Charge Q is distributed uniformly throughout an insulating sphere of radius R.The magnitude of the electric field at a point R/2 from the center is:

A point charge is placed at the center of a spherical Gaussian surface.The electric flux ϕ\phiϕ E is changed if:

The electric flux Φ through a surface:

A particle with charge +Q is placed outside a large neutral conducting sheet.At any point in the interior of the sheet the electric field produced by charges on the surface is directed:

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 outside the shell, a distance r from the center, is:

Charge is distributed uniformly on the surface of a large flat plate.The electric field 2 cm from the plate is 30 N/C.The electric field 4 cm from the plate is:

A spherical conducting shell has charge Q.A particle with charge q is placed at the center of the cavity.The charge on the inner surface of the shell and the charge on the outer surface of the shell, respectively, are:

A hollow conductor is positively charged.A small uncharged metal ball is lowered by a silk thread through a small opening in the top of the conductor and allowed to touch its inner surface.After the ball is removed, it will have:

Charge Q is distributed uniformly throughout a spherical insulating shell.The net electric flux through the outer 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 force on the charge q is:

Two large insulating parallel plates carry positive charge of equal magnitude 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.

Charge Q is distributed uniformly throughout a spherical insulating shell.The net electric flux through the inner surface of the shell is:

Charge is distributed uniformly along a long straight wire.The electric field 2 cm from the wire is 20 N/C.The electric field 4 cm from the wire is:

A 3.5-cm radius hemisphere contains a total charge of 6.6 *10-7 C.The flux through the rounded portion of the surface is 9.8 *104 N.m2/C.The flux through the flat base is:

Two large conducting 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 cylindrical wastepaper basket with a 0.15-m radius opening is in a uniform electric field of 300 N/C, perpendicular to the opening.The total flux through the sides and bottom is:

Positive charge Q is placed on a conducting spherical shell with inner radius R1 and outer radius R2.The electric field at a point r < R1 is:

A point particle with charge q is placed inside a cube but not at its center.The electric flux through any one side of the cube:

Which of the following graphs represents the magnitude of the electric field as a function of the distance from the center of a solid charged conducting sphere of radius R?

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A point charge is placed at the center of a spherical Gaussian surface.The electric flux $\phi$ _E is changed if:

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 outside the shell, 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 force on the charge q is:

A 3.5-cm radius hemisphere contains a total charge of 6.6 10^-7 C.The flux through the rounded portion of the surface is 9.8 10⁴ N.m²/C.The flux through the flat base is:

Positive charge Q is placed on a conducting spherical shell with inner radius R₁ and outer radius R₂.The electric field at a point r < R₁ is: