chapter 23

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:

10 N/C

A conducting sphere of radius 5.0 cm carries a net charge of 7.5 µC. What is the surface charge density on the sphere?

2.4x10^-4 C/m^2

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:

cannot be computed using Gauss' Law

The area vector for a flat surface:

is perpendicular to the surface and has a magnitude equal to the area of the surface

The electric flux Φ through a surface:

is the amount of electric field piercing the surface

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

the point charge is moved to just outside the sphere

To calculate the flux through a curved surface,

you must divide the surface into pieces that are tiny enough to be almost flat

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:

+3 C

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

+7 C

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:

-q, Q+q

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:

0

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

0

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:

21 N*m^2/C

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:

23 N*m^2/C

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:

30 N/C

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? A-down to the right, straight down, straight to the right on x B- horizontal right, curved down C- / the curved down D- curved up then curved down E- horizontal on x, straight up, curved down

D

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? A-down to the right, straight down, straight to the right on x B- horizontal right, curved down C- / the curved down D- curved up then curved down E- horizontal on x, straight up, curved down

E

Which statement is correct? 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.

Inward flux through a closed surface is negative and outward flux is positive

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

Q/eo