Charge Distribution

A metal sphere with radius r1 has a total electric charge of magnitude q. An uncharged metal sphere with radius r2 (with r1 > r2) is then connected by a wire to the first sphere, as illustrated above. The separation of the spheres is much greater than the radius of either sphere. When equilibrium is reached, the spheres will have

• charges on their surfaces of equal magnitude and the same sign

• charges on their surfaces of equal magnitude and opposite sign

• equal electric fields at their surfaces

• equal capacitances

• equal electric potentials

A positive electric charge is moved at a constant speed between two locations in an electric field, with no work done by or against the field at any time during the motion. This situation can occur only if the

• charge is moved in the direction of the field

• charge is moved opposite to the direction of the field

• charge is moved perpendicular to an equipotential line

• charge is moved along an equipotential line

• electric field is uniform

A proton moving along the positive x-axis enters an electric field that is directed along the positive y-axis. What is the direction of the electric force acting on the proton after it enters the electric field?

• along the negative z-axis

• along the positive z-axis

• along the negative y-axis

• along the positive y-axis

• The direction cannot be determined since the magnitude of the electric field is not known

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

A capacitor is constructed of two identical conducting plates parallel to each other and separated by a distance d. The capacitor is charged to a potential difference of V0 by a battery, which is then disconnected.

A sheet of insulating plastic material is inserted between the plates without otherwise disturbing the system. What effect does this have on the capacitance?

• It causes the capacitance to increase

• It causes the capacitance to decrease

• None; the capacitance does not change

• Nothing can be said about the effect without knowing the dielectric constant of the plastic

• Nothing can be said about the effect without knowing the thickness of the sheet.

Tags

NGSS.HS-PS3-5

Two small spheres are arranged along a line and carry charges of +4Q and –3Q, as shown in the figure above. The vertical lines are equally spaced.

At which of the labeled points does the electric field point toward the right with the smallest magnitude?

• A

• B

• C

• D

• E

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

A charge +𝑄 is inside a hollow region in an electrically neutral piece of solid metal, as shown above. The dashed line represents a Gaussian surface within the metal that completely encloses the hollow region.

At which of the three labeled points is the electric field equal to zero?

• X only

• Y only

• X and Z only

• Y and Z only

• X, Y, and Z

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

The conducting sphere in Figure 1 has a charge of −Q

and is electrically isolated so that there is no conducting path to or from the conducting object shown in Figure 2. The charges on the sphere are in equilibrium. The same charge −Q

is on the isolated conducting object. Which of the following correctly describes a change between the sphere in Figure 1 and the object in Figure 2?

• The charge is no longer located entirely on the surface of the object.

• The electric field inside the object is no longer zero everywhere

• The electric potential is no longer the same at all points inside the object.

• The electric field is no longer directed perpendicular to the surface at all points on the object

• The magnitude of the electric field is no longer the same at all points on the surface

Tags

NGSS.HS-PS2-4

If the only force acting on an electron is due to a uniform electric field, the electron moves with constant

• acceleration in a direction opposite to that of the field

• acceleration in the direction of the field

• acceleration in a direction perpendicular to that of the field

• speed in a direction opposite to that of the field

• speed in the direction of the field

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A battery or batteries connected to two parallel plates produce the equipotential lines between the plates shown above.

The force on an electron located on the 0-volt potential line is

• 0 N

• 1 N, directed to the right

• 1 N, directed to the left

• directed to the right, but its magnitude cannot be determined without knowing the the distance between the lines

• directed to the left, but its magnitude cannot be determined without knowing the distance between the lines

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

A battery or batteries connected to two parallel plates produce the equipotential lines between the plates shown above.

The force on an electron located on the 0-volt potential line is

• Q₂ = 16Q₁

• Q₂ = 4Q₁

• Q₂ = Q₁

• Q₂ = 0.25Q₁

Tags

NGSS.HS-PS2-4

NGSS.HS-PS2-5

NGSS.HS-PS3-5