physics II chapter 15 and 16 midterm study

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?

(3/4)^2

A point charge of +3.0 mC is located at the origin of a coordinate system and a second point charge of -6.0 mC is at x = 1.0 m. At what point on the x axis is the electrical potential zero?

+0.33 m

Two point charges of values +3.4 and +6.6 mC are separated by 0.10 m. What is the electrical potential at the point midway between the two point charges? (ke = 8.99 ´ 109 N×m2/C2)

+0.90 x 10^6 V

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

+5 uc

Four charges are at the corners of a square, with B and C on oppositecorners. 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 charge on A so that the force on B is zero?

-0.35 C

Q1 has 50 electric field lines radiating outward and Q2 has 100 field lines converging inward. What is the ratio Q1/Q2?

-1/2

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

-10 uc

Two point charges are placed along a horizontal axis with the following values and positions: +3.0 µC at x = 0 cm and -7.0 µC at x = 20 cm. At what point along the x axis is the electric field zero?

-38 cm

A charge of +2 C is at the origin. When charge Q is placed at 2 m along the positive x axis, the electric field at 2 m along the negative x axis becomes zero. What is the value of Q?

-8 C

Two equal charges, each Q, are separated by some distance. What third charge would need to be placed half way between the two charges so that the net force on each charge would be zero?

-Q/4

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?

0

A proton initially moves left to right long the x axis at a speed of 2.00 ´ 103 m/s. It moves into an electric field, which points in the negative x direction, and travels a distance of 0.200 m before coming to rest. If the proton's mass and charge are 1.67 ´ 10-27 kg and 1.60 ´ 10-19 C respectively, what is the magnitude of the electric field?

0.104 N/C

A proton (+1.6 ´ 10-19 C) moves 10 cm along the direction of an electric field of strength 3.0 N/C. The electrical potential difference between the proton's initial and ending points is:

0.30 V

Three capacitors of 1.0, 1.5, and 2.0 mF are connected in series. Find the combined capacitance.

0.46 mF

Two capacitors with capacitances of 1.5 and 0.25 mF, respectively, are connected in parallel. The system is connected to a 50-V battery. What charge accumulates on the 1.5-mF capacitor?

0.75 mC

At what distance from a point charge of 8.0 mC would the electrical potential be 4.2 ´ 104 V? (ke = 8.99 ´ 109 N×m2/C2)

1. 7 m

An electron in a TV picture tube is accelerated through a potential difference of 10 kV before it hits the screen. What is the kinetic energy of the electron in electron volts? (1 eV = 1.6 ´ 10-19 J)

1.0 x 10^4 eV

A proton initially moves left to right long the x axis at a speed of 2.00 ´ 103 m/s. It moves into an electric field, which points in the negative x direction, and travels a distance of 0.200 m before coming to rest. What acceleration magnitude does the proton experience?

1.00 x 10^7 /s^2

In x-ray machines, electrons are subjected to electric fields as great as 6.0 ´ 105 N/C. Find an electron's acceleration in this field. (me = 9.11 ´ 10-31 kg, e = 1.6 ´ 10-19 C)

1.1 x 10^17 m/s^2

A ping-pong ball covered with a conducting graphite coating has a mass of 5.0 ´ 10-3 kg and a charge of 4.0 µC. What electric field directed upward will exactly balance the weight of the ball? (g = 9.8 m/s2)

1.2 x 10^4 N/C

An electron is released from rest at the negative plate of a parallel-plate capacitor. If the distance across the plate is 5.0 mm and the potential difference across the plate is 5.0 V, with what velocity does the electron hit the positive plate? (me = 9.1 ´ 10-31 kg, e = 1.6 ´ 10-19 C)

1.3 x 10^6 m/s

Charge A and charge B are 3.00 m apart, and charge A is +2.00 C and charge B is +3.00 C. Charge C is located between them at a certain point and the force on charge C is zero. How far from charge A is charge C?

1.35 m

Two capacitors with capacitances of 1.5 mF and 0.25 mF, respectively, are connected in parallel. The system is connected to a 50-V battery. What electrical potential energy is stored in the 1.5-mF capacitor?

1.9 x 10^-3 J

If the distance between two negative point charges is increased by a factor of three, the resultant potential energy is what factor times the initial potential energy?

1/3

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

1/9

About how many electrons are in 30 grams of water (H2O)?

10^25

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? (ke = 8.99 ´ 109 N·m2/C2)

14.4 N (repulsive)

Two point charges are separated by 10.0 cm and have charges of +2.00 µC and -2.00 µC, respectively. What is the electric field at a point midway between the two charges? (ke = 8.99 ´ 109 N·m2/C2)

14.4 x 10^6 N/C

If an electron is accelerated from rest through a potential difference of 1 200 V, find its approximate velocity at the end of this process. (e = 1.6 ´ 10-19 C; me = 9.1 ´ 10-31 kg)

2.1 X 10^7 m/s

An electron with a speed of 2.0 ´ 106 m/s moves into a uniform electric field of 500 N/C that is parallel to the electron's motion. How long does it take to bring the electron to rest? (me = 9.11 ´ 10-31 kg, e = 1.6 ´ 10-19 C)

2.3 x 10^-8 s

A metallic object holds a charge of -3.8 ´ 10-6 C. What total number of electrons does this represent? (e = 1.6 ´ 10-19 C is the magnitude of the electronic charge.)

2.4 x 10^13

How much charge can be placed on a capacitor of plate area 10 cm2 with air between the plates before it reaches "atmospheric breakdown" where E = 3.0 ´ 106 V/m? (e0 = 8.85 ´ 10-12 C2/N×m2)

2.7 x 10^-8 C

Two point charges, separated by 1.5 cm, have charge values of +2.0 and -4.0 µC, respectively. Suppose we determine that 10 field lines radiate out from the +2.0-µC charge. If so, what might be inferred about the -4.0-µC charge with respect to field lines?

20 radiate in

Electrons in a particle beam each have a kinetic energy of 3.2 ´ 10-17 J. What is the magnitude of the electric field that will stop these electrons in a distance of 0.1 m? (e = 1.6 ´ 10-19 C)

2000 N/C

An electron is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the electron when it is 3.0 ´ 10-14 m away from the gold nucleus? (e = 1.6 ´ 10-19 C, ke = 8.99 ´ 109 N·m2/C2)

20N

What is the equivalent capacitance of the combination shown?

24 uF

Find the electrical potential at 0.15 m from a point charge of 6.0 mC. (ke = 8.99 ´ 109 N×m2/C2)

3.6 x 10^5 V

In a thundercloud there may be an electric charge of +40 C near the top of the cloud and -40 C near the bottom of the cloud. These charges are separated by about 2.0 km. What is the electric force between these two sets of charges? (ke = 8.99 ´ 109 N·m2/C2)

3.6 x 10^6 N

Two point charges, separated by 1.5 cm, have charge values of +2.0 and -4.0 µC, respectively. What is the value of the mutual force between them? (ke = 8.99 ´ 109 N×m2/C2)

320 N

Two capacitors with capacitances of 1.0 and 0.50 mF, respectively, are connected in series. The system is connected to a 100-V battery. What charge accumulates on the 1.0-mF capacitor?

33 mC

The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 1.60 ´ 107 m/s in a distance of 2.00 cm. What electric field is required? (me = 9.11 ´ 10-31 kg and e = 1.60 ´ 10-19 C)

36 400 N/C

Two point charges are 4 cm apart. They are moved to a new separation of 2 cm. By what factor does the resulting mutual force between them change?

4

Four identical 1-mF capacitors are connected together electrically. What is the greatest possible capacitance of the combination?

4 mF

Two identical iron spheres 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 (6 ´ 1023) of iron atoms? (ke = 8.99 ´ 109 N×m2/C2, the atomic number of iron is 26, and the electron charge is -1.6 ´ 10-19 C)

4 x 10^-10 %

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

4.0 nC

Two electrons are separated by one cm. What is the ratio of the electric force to the gravitational force between them? (me = 9.11 ´ 10-31 kg, ke = 8.99 ´ 109 N×m2/C2, G = 6.67 ´ 10-11 N×m2/kg2, and e = 1.6 ´ 10-19 C)

4.2 x 10^42

Charges of 4.0 µC and -6.0 µC are placed at two corners of an equilateral triangle with sides of 0.10 m. At the third corner, what is the electric field magnitude created by these two charges? (ke = 8.99 ´ 109 N·m2/C2)

4.8 x 10^6 N/C

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. By what factor will the electric field value at the 2R distance be changed if the charge value were increased to (4/3)Q?

4/3

A closed surface contains the following point charges: 6 C, 4 C, -2 C, -4 C. The electric flux coming out of the surface is:

4/Ceo

The average distance of the electron from the proton in the hydrogen atom is 0.51 ´ 10-10 m. What is the electric field from the proton's charge at the location of the electron? (ke = 8.99 ´ 109 N×m2/C2, e = 1.6 ´ 10-19 C)

5.5 x 10^11 N/C

If C = 10 µF, what is the equivalent capacitance for the combination shown?

5.8 uF

Using a 1-mF capacitor, a 2-mF capacitor, and a 3-mF capacitor, which of the following capacitances cannot be made by a combination that uses all three? (Hint: At most only 2 combinations must be considered to determine the correct answer.

5/11 mF

An electron with a charge value of 1.6 ´ 10-19 C is moving in the presence of an electric field of 400 N/C. What force does the electron experience?

6.4 x 10^-17 N

A 6.00 mC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.300 m. If the resulting force on the second charge is 6.40 N in the positive x-direction, what is the force on the charge at the origin?

6.40 N in the negative x-direction

A proton moving at 3.0 ´ 104 m/s is projected at an angle of 30° above a horizontal plane. If an electric field of 400 N/C is acting down, how long does it take the proton to return to the horizontal plane? (Hint: Ignore gravity. mproton = 1.67 ´ 10-27 kg, qproton = 1.6 ´ 10-19 C)

7.8 x 10^-7 s

An airplane is flying through a thundercloud at a height of 2 000 m. (This is a very dangerous thing to do because of updrafts, turbulence, and the possibility of electric discharge.) If there is a charge concentration of +40 C at height 3 000 m within the cloud and -40 C at height 1 000 m, what is the magnitude of the electric field E at the aircraft? (ke = 8.99 ´ 109 N·m2/C2)

720,000 N/C

An electron in a cathode ray tube is accelerated through a potential difference of 5.0 kV. What kinetic energy does the electron gain in the process? (e = 1.6 ´ 10-19 C)

8.0 x 10^-16 J

In Millikan's oil drop experiment, if the electric field between the plates was of just the right magnitude, it would exactly balance the weight of the drop. Suppose a tiny spherical oil droplet of radius 1.6 ´ 104 cm carries a charge equivalent to one electron. What electric field is required to balance the weight? (The density of oil is 0.85 g/cm3, e = 1.6 ´ 10-19 C.)

8.9 x 10^5 N/C

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?

9.0

We have an initially uncharged hollow metallic sphere with radius of 5.0 cm. I place a small object with a charge of +10 µC at the center of the sphere through a hole in the surface. Find the electric field present at a point 10 cm from the sphere's center. (ke = 8.99 ´ 109 N×m2/C2)

9.0 x 10^6N/C

A parallel-plate capacitor has dimensions 4.0 cm ´ 5.0 cm. The plates are separated by a 1.0-mm thickness of paper (dielectric constant k = 3.7). What is the charge that can be stored on this capacitor, when connected to a 1.5-V battery? (e0 = 8.85 ´ 10-12 C2/N×m2)

9.8 x 10^-11 C

Charge A has 10 electric field lines coming out, Charge B has 20 lines coming out, and Charge C has 30 lines coming in. Which pair of these charges will have the largest force between them if placed one cm apart?

B and C

The unit of capacitance, the farad, is dimensionally equivalent to which of the following?

C/V

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

Electrons are added to the rod

he unit of electrical potential, the volt, is dimensionally equivalent to:

J/C

Who was the first to determine the electron's charge?

Millikan

electric field is dimensionally equivalent to which of the following

N/C

The constant ke, which appears in Coulomb's law formula, is equivalent dimensionally to which of the following?

Nxm^2/c^2

I wish to use a positively charged rod to charge a ball by induction. Which statement is correct?

The ball must be a conductor

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

The electrical field inside the conductor must be zero

Two charges, +Q and -Q, are located two meters apart and there is a point along the line that is equidistant from the two charges as indicated. Which vector best represents the direction of the electric field at that point?

Vector Ea

In which case does an electric field do positive work on a charged particle?

a negative charge moves opposite to the direction of the electric field

A repelling force must occur between two charged objects under which conditions?

charges are of like signs

Which of the following best characterizes electrical insulators?

charges on the surface don't move

The combination of two separated point charges of opposite sign but equal magnitude is called an electric:

dipole

Which of the following best characterizes electrical conductors?

electric charges move freely

The quantity of electrical potential, the volt, is dimensionally equivalent to:

electric field ' distance

The beam of electrons that hits the screen of an oscilloscope is moved up and down by:

electrical charges on deflecting plates

When a glass rod is rubbed with silk, which of the following statements best describes what happens?

electrons are removed from the rod

The number of electric field lines passing through a unit cross sectional area is indicative of:

field strength

Of the following substances, which one contains the highest density of free electrons?

iron

If two parallel, conducting plates have equal positive charge, the electric field lines will:

leave both plates and go to infinity

If body M, with a positive charge, is used to charge body N by induction, what will be the nature of the charge left on the latter?

must be negative

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?

must be positive

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

none of the above is correct

The electric field at the surface of a positively charged conductor has a direction characterized by which of the following?

perpendicular outward and away from charge

An uncharged conductor is supported by an insulating stand. I pass a positively charged rod near the left end of the conductor, but do not touch it. The right end of the conductor will be:

positive

If the distance between two isolated parallel plates that are oppositely charged is doubled, the electric field between the plates is essentially unchanged. However, the:

potential difference between the plates will double

The electric field of a point charge has an inverse ____ behavior.

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:

stays the same

The Millikan oil-drop experiment demonstrated that:

the electronic charge is quantized

Consider two charged spheres, one with charge +2 C and the other with -2 C. A proton (a positively charged particle) is at the point halfway between the spheres. What is not zero?

the force on the proton

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:

the outside surface of the conductor will become positively charged

Relative distribution of charge density on the surface of a conducting solid depends on:

the shape of the conductor

The electric field associated with a uniformly charged hollow metallic sphere is the greatest at:

the sphere's outer surface

Two capacitors with CA greater than CB are connected in parallel with a battery. Which of the following is true?

there is the same potential difference across both capacitors

When charging two objects by rubbing them together:

they must be made of different material

At what point is the charge per unit area greatest on the surface of an irregularly shaped conducting solid?

where curvature is greatest

An electron (charge -1.6 ´ 10-19 C) moves on a path perpendicular to the direction of a uniform electric field of strength 3.0 N/C. How much work is done on the electron as it moves 15 cm?

zero

Two point charges each have a value of 30.0 mC and are separated by a distance of 4.00 cm. What is the electric field midway between the two charges? (ke = 8.99 ´ 109 N·m2/C2)

zero