Physics Ch.23

A Gaussian sphere is inside a ball of uniform negative charge, concentric with the ball. Which describes the amount of charge enclosed by the Gaussian sphere?

The enclosed charge is proportional to the volume of the Gaussian sphere.

Which describes the electric field of a ball of uniform positive charge?

The field is maximum at the surface and progressively smaller as you move away from the surface, either toward the center or away from the center.

Which describes the electric field outside a charged metal surface?

The field is proportional to the surface charge density.

Which describes the electric field outside a flat plastic sheet with uniform charge?

The field is proportional to the surface charge density.

Which describes the direction of the electric field outside a positively charged flat metal surface?

The field vectors point directly away from the surface

Which describes the direction of the electric field outside a flat plastic sheet with uniform positive charge?

The field vectors point directly away from the surface.

Which describes the direction of the electric field outside a flat plastic sheet with uniform negative charge?

The field vectors point directly toward the surface.

Which describes the direction of the electric field outside a negatively charged flat metal surface?

The field vectors point directly toward the surface.

If a closed surface encloses a net negative charge, which describes the flux through the surface?

The flux is negative because the electric field is inward.

Which describes the flux of an electric field that pierces inward through a section on a closed surface?

The flux is negative.

If a closed surface encloses a net positive charge, which describes the flux through the surface?

The flux is positive because the electric field is outward

Which describes the flux of an electric field that pierces outward through a section on a closed surface?

The flux is positive.

If a closed surface encloses equal amounts of positive charge and negative charge, which describes the flux through the surface?

The flux is zero.

Which describes the flux of an electric field that is tangent to a section on a closed surface?

The flux is zero.

A negatively charged particle is placed inside (in the hollow of) a shell of uniform negative charge. Which describes the force on the particle due to the shell?

The force is zero.

A positively charged particle is placed inside (in the hollow of) a shell of uniform negative charge. Which describes the force on the particle due to the shell?

The force is zero.

How do we calculate the charge quantity used in Gauss' law for a closed surface?

We add the algebraic values of all charges (signs included) enclosed by the surface.

When is the electric flux on a section of a closed surface positive?

When the electric field is in the direction of the section's area vector.

When is the electric flux on a section of a closed surface negative?

When the electric field is in the direction opposite that of the section's area vector.

When is the electric flux on a section of a closed surface zero?

When the electric field is perpendicular to the section's area vector.

When is the electric flux on a section of a closed surface zero?

When the electric field is tangent to the section.

When is the electric flux on a section of a closed surface negative?

When the electric field pierces inward through the section.

When is the electric flux on a section of a closed surface positive?

When the electric field pierces outward through the section.

When we embed a Gaussian cylinder in a flat metal surface with uniform charge, perpendicular to the surface, where is there flux through the surfaces of the cylinder?

the end face outside the metal

When we stick a Gaussian cylinder through a flat plastic sheet with uniform charge, perpendicular to the sheet, where is the flux through the surfaces of the cylinder?

the end faces outside the sheet

When we embed a Gaussian cylinder in a flat metal surface with uniform charge, perpendicular to the surface, what gives the amount of charge enclosed by the cylinder?

the product of the surface charge density and the cross-sectional area of the cylinder

When we stick a Gaussian cylinder through a flat plastic sheet with uniform charge, perpendicular to the sheet, what gives the amount of charge enclosed by the cylinder?

the product of the surface charge density and the cross-sectional area of the cylinder

In evaluating the integral in Gauss' law for a spherical surface centered on a charged particle, what does the integration of dA give you?

the surface area of the sphere

Which describes the electric flux through a section of a closed surface?

It is a scalar.

A negatively charged particle is placed outside a shell of uniform negative charge. Which describes the force vector on the particle due to the shell?

It is directed away from the center of the shell.

A positively charged particle is placed outside a shell of uniform positive charge. Which describes the force vector on the particle due to the shell?

It is directed away from the center of the shell.

A negatively charged particle is placed outside a shell of uniform positive charge. Which describes the force vector on the particle due to the shell?

It is directed toward the center of the shell.

A positively charged particle is placed outside a shell of uniform negative charge. Which describes the force vector on the particle due to the shell?

It is directed toward the center of the shell.

Which describes the vector calculation of the electric flux through a section of a closed surface?

It is the dot product of the electric field and the section's area vector.

Which gives the amount of charge on a certain length of a rod that is uniformly charged?

It is the product of the length and the linear charge density.

Which gives the linear charge density of a uniformly charged rod?

It is the ratio of the charge to the length.

Which describes Gauss' law?

It relates the net flux through a closed surface to the net charge enclosed by the surface.

In evaluating the integral in Gauss' law for a spherical surface centered on a negatively charged particle, which describes the dot product of the electric field and a differential area vector?

The dot product is negative because the vectors are in opposite directions

In evaluating the integral in Gauss' law for a spherical surface centered on a positively charged particle, which describes the dot product of the electric field and a differential area vector?

The dot product is positive because the vectors are in the same direction.

We place a closed Gaussian cylinder around a rod with uniform negative charge, coaxial with the rod. Which describes the electric field through the cylinder?

The electric field is inward through the curved side.

We place a closed Gaussian cylinder around a rod with uniform positive charge, coaxial with the rod. Which describes the electric field through the cylinder?

The electric field is outward through the curved side.

A Gaussian sphere is inside a ball of uniform negative charge, concentric with the ball. Which describes the electric field through the surface of the Gaussian sphere?

The electric field is radially inward.

A Gaussian sphere is inside a ball of uniform positive charge, concentric with the ball. Which describes the electric field through the surface of the Gaussian sphere?

The electric field is radially outward.

Which describes the electric field outside and inside a charged metal surface that is flat and large?

The electric field is zero inside and uniform (and nonzero) outside.

We bring an electron near a negatively charged flat metal sheet. Which describes the surface charge density at the region on the sheet that is closest to the electron?

The presence of the electron decreases the magnitude of the surface charge density.

We bring an electron near a positively charged flat metal sheet. Which describes the surface charge density at the region on the sheet that is closest to the electron?

The presence of the electron increases the magnitude of the surface charge density.

We bring a proton near a positively charged flat metal sheet. Which describes the surface charge density at the region on the sheet that is closest to the proton?

The presence of the proton decreases the magnitude of the surface charge density.

We bring a proton near a negatively charged flat metal sheet. Which describes the surface charge density at the region on the sheet that is closest to the proton?

The presence of the proton increases the magnitude of the surface charge density.

We place a closed Gaussian cylinder around a rod with uniform negative charge, coaxial with the rod. Then we pick a small region on the curved surface of the cylinder. Which describes the electric field there and the area vector of the small region?

The vectors are in opposite directions.

We place a closed Gaussian cylinder around a rod with uniform positive charge, coaxial with the rod. Then we pick a small region on the curved surface of the cylinder. Which describes the electric field there and the area vector of the small region?

The vectors are in the same direction.

Which describes the electric field vectors near a rod with uniform negative charge?

The vectors are radially inward toward the rod.

A Gaussian sphere is inside a ball of uniform negative charge, concentric with the ball. Which describes the electric field vectors along the surface of the Gaussian sphere?

The vectors are radially inward.

Which describes the electric field vectors near a rod with uniform positive charge?

The vectors are radially outward from the rod

A Gaussian sphere is inside a ball of uniform positive charge, concentric with the ball. Which describes the electric field vectors along the surface of the Gaussian sphere?

The vectors are radially outward.

Which describes the electric field lines outside a flat plastic sheet with uniform positive charge?

They extend directly away from the sheet

Which describes the electric field lines outside a positively charged flat metal surface?

They extend directly away from the surface.

Which describes the electric field lines outside a flat plastic sheet with uniform negative charge?

They extend directly toward the sheet.

Which describes the electric field lines outside a negatively charged flat metal surface?

They extend directly toward the surface.