Chapter 15: Electrostatics

A spherical surface surrounds a point at its center.

Flux increases and E decreases

Three equal positive charges are placed on the x-axis, one at the origin, one at x = 2 m, and the third at x = 4 m. Of the following points, which has the greatest magnitude electric field?

c. x = 5 m

A charge Q accumulates on the hollow metallic dome, of radius R, of a Van de Graaff generator. A probe measures the electric field strength at various points outside the sphere surface. If the probe is initially at a distance 3R from the sphere's center and then is moved to 4R, by what factor will the electric field reading change?

d. (3/4)^2

An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of +10µC carefully placed at the center of the sphere through a hole in the latter's surface. What charge resides outer surface of the sphere?

d. +10 uC

Q1 = 50 electric field lines radiate outward and Q2 = 100 electric field line converge inward.

d. -1/2

Two point charges are placed along a horizontal axis. +3 uC at x = 0 cm.

d. -38 cm

A charge of +2 C is at the origin.

d. -8 C

The constant "k" is

N * m^2/C

A thin uncharged conducting spherical shell has a charge q carefully placed at its center through a small hole in the shell. The charge q does not touch the shell. What is the charge on the shell?

d. 0

If the distance between two point charges is tripled, the mutual force between them will be changed by what factor?

d. 1/9

Two point charges are 4 m apart. New separation of 2 m. Factor of resulting force?

d. 4

Two identical iron sphere have equal positive charges and the force between them when they are 1 m apart is 1 N. What percentage of the electrons has been removed from each sphere if each sphere has 1 mole of iron atoms?

d. 4 x 10^-10 %

Two electrons are separated by 1 cm. Ratio of electric to gravitational force?

d. 4.2 x 10^42

Charges of 4.0 uC and -6uC are placed at two corners of an equilateral triangle.

d. 4.8 x 10^6

An airplane is flying through a thundercloud at a height of 2000 m

d. 720,000

Two small objects are suspended from threads.

d. All of the above

Two identical balls have the same amount of charge, bu the charge on ball A is positive and the charge on ball B is negative. The balls are placed on a smooth, level, friction-less table whose top is an insulator. Which of the following is true?

d. None of the above are correct

In the Millikan oil-drop experiment it was found that oil droplets:

d. could have positive, negative, or zero net charge.

Two point charges each have a value of 30.0 mC and separated by a distance of 4 cm.

d. zero

Four charges are at the corners of a square, with B and C on opposite corners. Charges A and D, on the other two corners, have equal charge, while both B and C have a charge of +1.0 C. What is the on A so that the force on B is zero?

C. -0.35

We have a hollow metallic sphere with charge -5.0μC and radius 5.0 cm. We insert a +10μC charge at the center of the sphere through a hole in the surface. What charge now rests on the outer surface of the sphere?

a. +5 uC

In x ray machines, electrons are subjected to electric fields as great as 6.0 x 10^5 N/C.

a. 1.1 x 10^17

An electron with a speed of 2.0 x 10^6 m/s moves into a uniform electric field of 500 N/C.

a. 2.3 x 10^-8

An electron is sent at high speed to a gold nucleus. What is the electrical force?

a. 20 N

Two point charges, separated by 1.5 cm, have charge values +2 and -4. Value of mutual force.

a. 320 N

The average distance between of an electron from a proton in the hydrogen atom is 0.51 x 10^-10 m.

a. 5.5 x 10^11

A 6.0 uC charge is placed at the origin and a second charge is placed at the axis x = 0.3. Force on Second Charge = 6.4 N.

a. 6.4 N in negative direction

A proton moving at 3.0 x 10^4 m/s at an angle of 30 degrees

a. 7.8 x 10^-7

If the size of the charge value is tripled for both of two point charges maintained at a constant separation, the mutual force between them will be changed by what factor?

a. 9.0

A 6.0 uC charge is placed at the origin and a second charge is placed at the axis x = 0.3. Force on Second charge = 5.4 N.

a. 9uC

When a glass rod is rubbed with silk, wotf statement best describes.

a. Electrons removed from the rod

Two charges, +Q and -Q, are located two meters apart.

a. Vector Ea

Wotf best characterizes electrical insulators?

a. charges on surface don't move

Relative distribution of charge density at a surface of a conducing solid depends on

a. shape of conductor

An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of +10µC carefully placed at the center of the sphere through a hole in the latter's surface. What charge resides inner surface of the sphere?

b. -10 uC

A proton initially moves left and right along the x-axis at a speed of 2.0 x 10^3 m/s. Acceleration.

b. 1.00 x 10^7 m/s^2

A Van de Graaff generator has a spherical dome of 20 cm. Operating in dry air. Atmospheric breakdown.

b. 1.3 x 10^-5

Two identical spheres each carry a charge of 40.0 µC. The spheres are separated by a distance of 1.00 m. What is the electric force between the spheres?

b. 14.4 N (repulsive)

Two point charges are separated by 10 cm and have charges of +2 uC and -2uC.

b. 14.4 x 10^6

A spherical volume of space has an electric field of intensity 100 N/C directed radially outward from it surface of radius 0.600 m. What is the net charge enclosed within this surface?

b. 4.0 nC

A charge Q accumulates on the hollow metallic dome, of radius R, of a Van de Graaff generator. A probe measures the electric field strength at various points outside the sphere surface. Distance of 2R.

b. 4/3

Doug rubs a piece of fur on a hard rubber rod, giving the rod a negative charge. What happens?

b. Electrons are added to the rod

Electric field is equivalent to what?

b. N/C

If a conductor is in electrostatic equilibrium near an electrical charge:

b. the electric field inside the conductor must be zero.

If a charge +Q is placed inside a hollow isolated conductor that is originally neutral and the charge does not touch that conductor at any time:

b. the outside surface of the conductor will become positively charged.

Charges q, q, and -q are placed on the x-axis.

b. x = 3 m

A proton initially moves left and right along the x-axis at a speed of 2.0 x 10^3 m/s. Magnitude of shield.

c. 0.104 N/C

Charge A and B are 3 m apart. Charge A is +2 and B is +3.

c. 1.35 m

Two point charges, separated by 1.5 cm, have charge values +2 and -4. 10 field lines radiate out from +2. What can be inferred about -4?

c. 20 radiate in

Electrons in a particle beam each have a kinetic energy of 3.2 x 10^-17 J.

c. 2000 N/C

In a thundercloud there may be an electric charge of +40 C near the top of the cloud and -40 C at the bottom. Separation of 2 km.

c. 3.6 x 10^6

The electric field in a cathode tube is suppose to accelerate electrons from 0 to 1.6x10^7 in 2 cm.

c. 36,400 N/C

An electron with a charge value of 1.6 x 10^-19 in the presence of an electric field of 400 N/C.

c. 6.4 x 10^-17

An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of +10µC carefully placed at the center of the sphere through a hole in the latter's surface. What is the electric field present?

c. 9.0 x 10^6

Object A has a charge q on it, object B has a charge q on it, and Object C has a charge 2q on it. These charges are arranged, one each, at the vertices of an equilateral triangle. Which charge has the greatest magnitude electric force on it?

c. C

Who was the first to determine electron charge?

c. Millikan

Wotf best characterizes electrical conductors?

c. electric charges move freely

If body P, with a positive charge, is placed in contact with body Q (initially uncharged), what will be the nature of the charge left on Q?

c. must be positive

The electric field of a point charge has an inverse ______________ behavior

c. r^2

A charge, +Q, is placed inside a balloon and the balloon is inflated. As the radius of the balloon r increases the number of field lines going through the surface of the balloon:

c. stays the same

The Millikan oil-drop experiment demonstrated that:

c. the electronic charge is quantized.