Physics 2 Exam 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

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 = 1.00 m. What is the electric potential at the x = 0.50 m point? (ke = 8.99 ´ 109 N×m2/C2)

-5.4 ´ 104 V

A 9.0-V battery moves 20 mC of charge through a circuit running from its positive terminal to its negative terminal. How much energy was delivered to the circuit?

0.18 J

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.

A resistor is connected to a battery with negligible internal resistance. If you replace the resistor with one that has twice the resistance, by what factor does the power dissipated in the circuit change?

0.50

Three resistors connected in parallel have individual values of 4.0, 6.0 and 10.0 W, respectively. If this combination is connected in series with a 12-V battery and a 2.0-W resistor, what is the current in the 10-W resistor?

0.59 A

A pair of parallel plates, forming a capacitor, are connected to a battery. While the capacitor is still connected to the battery maintaining a constant voltage, the plates are pulled apart to double their original distance. What is the ratio of the final energy stored to the original energy stored?

1/2

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

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

1/4 mF

Replacing a wire resistor with another of the same material and length but with three times the diameter will have the effect of changing the resistance by what factor?

1/9

A "sandwich" is constructed of two flat pieces of metal (2.00 cm on a side) with a 2.00-mm-thick piece of a dielectric called Rutile (k = 100) in between them. What is the capacitance? (e0 = 8.85 ´ 10-12 C2/N×m2)

177 pF

A pair of parallel plates, forming a capacitor, are charged. The plates are pulled apart to double the original separation, the charges on the plates remaining the same. What is the ratio of the final energy stored to the original energy stored?

2

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 ´ 107 m/s

What is the equivalent resistance for these 3.00-W resistors?

2.25 W

A 9.0-V battery is connected between two parallel metal plates 4.0 mm apart. What is the magnitude of the electric field between the plates?

2.3 ´ 103 N/C

Three 8.0-W resistors are connected in parallel. What is their equivalent resistance?

2.7 W

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 ´ 10-8 C

The temperature coefficient of resistivity for a "perfect" ohmic material would be:

24.0 W

Three 8.0-W resistors are connected in series. What is their equivalent resistance?

24.0 W

The charge flowing through a light bulb attached to a 12.0-V battery in 14.0 s is 30.0 C.What is the average power supplied by the battery during this process?

25.7 W

Three 4.0-W resistors are connected in parallel to a 12.0-V battery. What is the current in any one of the resistors?

3.0 A

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

4 mF

Two resistors of values 6.0 and 12.0 W are connected in parallel. This combination in turn is hooked in series with a 2.0-W resistor and a 24-V battery. What is the current in the 2-W resistor?

4.0 A

Four point charges are on the rim of a circle of radius 10 cm. The charges are (in mC) +0.50, +1.5, -1.0, -0.50. If the electrical potential at the circle's center due to the +0.5 charge alone is 4.5 ´ 104 V, what is the total potential at the center due to the four charges combined?

4.5 ´ 104 V

A proton (+1.6 ´ 10-19 C) moves 10 cm on a path in the direction of a uniform electric field of strength 3.0 N/C. How much work is done on the proton by the electrical field?

4.8 ´ 10-20 J

Two resistors of values 6.0 and 12.0 W are connected in parallel. This combination in turn is hooked in series with a 4.0-W resistor. What is the overall resistance of this combination?

8.0 W

The size of the electric current in a electrical conductor is a function of which of the following?

All of the above choices are valid.

Resistor A has twice the resistance of resistor B. When individually connected across a given potential difference, which one dissipates the most power; and when connected in series across the same potential difference, which one dissipates the most power?

B, A

To find the equivalent resistance of the combination of resistors shown below by the method of possibly repeated applications of combining resistors in series and /or combining resistors in parallel, the first step would be which of the following?

Combine the 4.0 W and the 10.0 W in series.

To find the equivalent resistance of the combination of resistors shown across the 28-V battery by the method of possibly repeated applications of combining resistors in series and /or combining resistors in parallel, the first step would be which of the following?

Combine, in series, the two 3-W resistors and the 4-W resistor in the right-hand branch of the circuit.

Three resistors connected in parallel have the individual voltages labeled DV1, DV2 and DV3, respectively. Which of the following expresses the total voltage DVT across the three resistors when connected in this manner?

DVT = DV1 = DV2 = DV3

A capacitor is attached across a battery and charged. Then the battery is removed leaving the capacitor charged. The positive lead of the capacitor is then connected to one lead of a previously uncharged identical capacitor, and then the other lead of the charged capacitor is connected to the other lead of the second capacitor. How does the energy Eo stored in the originally charged capacitor compare to the energy Ef stored in the connected capacitors?

Eo = 2Ef

Three resistors connected in series each carry currents labeled I1, I2 and I3. Which of the following expresses the value of the total current IT in the system made up of the three resistors in series?

IT = I1 = I2 = I3

Case 1: An electron is released from rest in a uniform electric field. Case 2: A proton is released from rest in a uniform electric field of the same magnitude as in case 1. How does the electric potential energy of the charge-field system behave in these cases?

In both cases, the potential energy decreases.

If the current in a wire is tripled, what effect does this have on the electron drift velocity in the wire?

It triples.

The quantity volt is equivalent to which of the following?

J/C

Two wires with the same resistance have the same diameter but different lengths. If wire 1 has length L1 and wire 2 has length L2, how do L1 and L2 compare if wire 1 is made from copper and wire 2 is made from aluminum? The resistivity of copper is 1.7 ´ 10-5 W·m and the resistivity of aluminum is 2.82 ´ 10-5 W·m.

L1 = 1.7 L2

A wire has resistance R. A second wire has twice the length, twice the diameter, and twice the resistivity of the first wire. What is its resistance?

R

If R1 < R2 < R3, and if these resistors are connected in parallel in a circuit, which one has the highest current?

R1

If R1 < R2 < R3, and if these resistors are connected in series in a circuit, which one dissipates the greatest power?

R3

Three resistors, each with resistance R1, are in series in a circuit. They are replaced by one equivalent resistor, R. Comparing this resistor to the first resistor of the initial circuit, which of the following is true?

The current through R equals the current through R1.

Three resistors, each with resistance R1, are in parallel in a circuit. They are replaced by one equivalent resistor, R. Compare this resistor to the first resistor of the initial circuit. Which of the following statements is true?

The voltage across R equals the voltage across R1.

The unit of electric resistance, the ohm, is equivalent to which of the following?

V/A

The unit of electric current, the ampere, is equivalent to which of the following?

V/W

Resistors of values 8.0 W, 12.0 W, and 24.0 W are connected in parallel across a fresh battery. Which resistor dissipates the greatest power?

the 8.0-W resistor

A light bulb with a tungsten filament is attached to a source of variable voltage. As the voltage is increased on the bulb,

the bulb's resistance increases.

Doubling the voltage across a parallel plate capacitor does not double which of the following?

the energy stored

Resistors of values 8.0 W, 12.0 W, and 24.0 W are connected in series across a battery with a small internal resistance. Which resistor dissipates the greatest power?

the 24.0-W resistor

A free electron is in an electric field. With respect to the field, it experiences a force acting:

anti-parallel (opposite in direction).

Ten coulombs of charge start from the negative terminal of a battery, flow through the battery and then leave the positive terminal through a wire, flow through a resistor and then return to the starting point on this closed circuit. In this complete process, the ten coulombs:

have no net change in potential energy.

The internal resistances of an ideal voltmeter and an ideal ammeter are respectively (ideal meaning the behavior of the system is not changed when using the meter):

infinite and zero.

If a certain resistor obeys Ohm's law, its resistance will change:

none of the above, since resistance is a constant for the given resistor.

Materials having resistance changes as voltage or current varies are called:

nonohmic.

Household circuits are wired in ________.

parallel

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.