Physics 192 Study Guide (old exams)
A certain ideal gas thermometer is dipped into water boiling at atmospheric pressure, the mercury level in the right arm is 1279 mm above the reference mark (assume this reference mark to be equal to 0 mm of Mercury and corresponds to absolute zero). When the thermometer is removed from the water and allowed to reach room temperature, the mercury level drops by 267 mm. You correctly calculate that the room is a sweltering 30 degrees C and reach to wipe the sweat off your brow.
false
A magnetic monopole (the magnetic analog to a point charge) is easily created by isolating one of the atoms which make up a standard bar magnet (imagine breaking up the magnet until you only have one atom left, this would act like a magnetic monopole).
false
Background assumed to be true: Recall the tape laboratory where we first investigated electric charge. You place two identical strips of tape on top of each other and then quickly separate them. Statement to be subjected to scrutiny: You would (correctly) expect the two pieces of tape to repel one another because they have the same sign of charge.
false
Background assumed to be true: Two identical samples of ideal gas experience a change of state to the same final temperature. Sample 1 expands isobarically, while sample 2 undergoes an isochoric process. Statement subject to scrutiny: Sample 2 required more heat than sample 1.
false
Background assumed to be true: Two uniformly charged spheres are firmly fastened to and electrically insulated from frictionless pucks on an air table. The distance between the two spheres is much larger than their diameters. The charge on sphere 2 is three times the charge on sphere 1. Statement to be subjected to scrutiny: The electrostatic force exerted by sphere 2 on sphere 1 is three times that of the electrostatic force exerted by sphere 1 on sphere 2.
false
Background information to be assumed true: In the figure below, 4 non-identical light bulbs are connected across the battery. Bulb A is brighter than bulb B, which is brighter than bulb C, which is brighter than bulb D. We assume that brighter bulbs have greater potential differences. Statement to be evaluated: It is possible for the potential difference across bulb C to be 3 V.
false
If the electric field is zero everwhere inside a region of space, the potential must also be zero in that region.
false
The electric field has no physical consequence, it is merely a mathematical tool to understand force is communicated between two charged particles.
false
The energy-transfer diagram represents a physically allowable heat engine.
false
Assuming you have a sample of diatomic molecules, for what pressure will the mean free path in room temperature nitrogen (20 degrees C) be 4.6 m? A) 6.9x10^-8 atm B) 2.2x10^-7 atm C)4.9x10^-8 atm D) 1.5x10^-7 atm
need to check answer
A dipole placed in a uniform electric field is considered in unstable equilibrium if the dipole moment is anti-parallel to the electric field.
true
A voltmeter should have an internal resistance much greater than the load resistance and internal resistance of the source (battery).
true
The electric field inside of the cavity enclosed by a thin, conducting shell is zero unless some charge is enclosed by the thin, conducting shell.
true
The fire syringe demo (ignition of cotton) is a good model of an adiabatic process as the compression occurs so rapidly that the gas particles do not have time to collide and exchange energy (heat).
true
When you rub an inflated balloon against your head, the balloon acquires a net charge due to the friction between your hair and the balloon surface. The balloon then interacts with a neutral, insulating wall because the charge of the balloon polarizes the neutral object leading to an attractive force between the balloon and the wall.
true
You are able to increase the temperature of the hot reservoir of a thermal process by 100 K or decrease the temperature of the cold reservoir of the same thermal process by 100 K. If your goal is to increase the efficiency of an ideal Carnot engine, you should decrease the temperature of the cold reservoir.
true
A Carnot engine operates between a high temperature reservoir at 435 K and a river with water at 280 K. If it absorbs 3700 J of heat each cycle, how much work per cycle does it perform? A) 2251 J B) 2382 J C) 1318 J D) 1449 J
C
A charge Q is uniformly spread over one surface of a very large non-conducting square elastic sheet having sides of length d. At a point P that is 1.25 cm outside the sheet, the magnitude of the electric field due to the sheet is E. If the sheet is now stretched so that its sides have length 3d, what is the magnitude of the electric field at P? A) E/3 B) 3E C) E/9 D) E E) 9E
C
A flat 1.0 m^2 surface is vertical at x= 2.0 m and parallel to the yz-plane. What is the flux through the surface if it is located in a uniform electric field given by E = 29i + 42j + 62k N/C? A) 110 Nm^2/C B) 0 Nm^2/C C) 29 Nm^2/C D) 50 Nm^2/C E) 61 Nm^2/C
C
A glass window pane is 2.7 m high, 2.4 m wide, and 2.0 mm thick. The temperature at the inner surface of the glass is 22 degrees C and at the outer surface is 4 degrees C. How much heat is lost each hour through the window under steady state conditions? A) 4.7x10^1 J B) 4.7x10^4 J C) 4.7x10^8 J D) 4.7x10^5 J E) 4.7x10^6 J
C
A gold wire that is 1.6 mm in diameter and 21 cm long carries a current of 350 mA. How many electrons per second pass a given cross section of the wire? A) 1.2x10^23 B) 2.9x10^15 C) 2.2x10^18 D) 6.3x10^15 E) 2.2x10^17
C
In the circuit shown in the figure, four identical resistors labeled A to D are connected to a battery as shown. S1 and S2 are switches. Which of the following actions would result in the least amount of current through resistor A?
C
The graph in the figure shows that variation of the electric potential V as a function of the radial direction r (measured in meters). For which range or value of r is the magnitude of the electric field the largest? A) from r=0 to r=3 B) at r=3 C) from r=3 to r=4 D) form r=4 to r=6 E) at r=4
C
Which electric field is responsible for the proton's trajectory shown? A B C D E
C
Your very unrealistic boss cannot figure out the largest current the following circuit could ever produce. They ask you to complete the circuit with any of the resistors which exist in the drawers in your lab space. What is the largest possible current that the following circuit could produce? A) 0.05 A B) 1.0 A C) 0.099 A D) 10 A E) 0.001 A
C
In the figure, all the charges are point charges and the charge in the middle is Q = -8.0 nC. For what charge q1 will charge q2 be in static equilibrium? A) 16 nC B) 64 nC C) 8 nC D) 32 nC
D
All of the wires shown below are made of the same material. Which is the correct ranking, from largest to smallest, of the resistances of these wires? A) R1>R2>R3>R4>R5 B) R4>R5>R1>R2>R3 C) R5>R4=R3>R2=R1 D) R1=R3>R2=R4>R5 E) R4>R1=R5>R3>R2
E
Consider two identically constructed ordinary thermometers. One thermometer is calibrated according to the Celsius scale and the other thermometer is calibrated according to the Fahrenheit scale. When both thermometers are inserted into a warm water bath, we would expect A) the Fahrenheit thermometer to display a larger number B) the Celsius thermometer to display a smaller number C) the level of fluid in the thermometers to be at the same height D) both A and B are correct E) All are correct
E
For a fixed amount (or number of moles) of gas, if the absolute temperature of the gas is doubled, what happens to the pressure of the gas? A) The pressure of the gas becomes eight times the original pressure. B) The pressure of the gas becomes double the original pressure. C) The pressure of the gas becomes four times the original pressure. D) The pressure of the gas becomes one half the original pressure. E) The answer cannot be determined without volume information.
E
The equipartition theorem explains A) the difference between CV values for monatomic and diatomic gases. B) why most solids have a molar specific heat capacity of around 25 J/(mol K). C) the method for breaking physics problems into equal parts to make solving them easier. D) that energy is shared equally among the various degrees of freedom and is slightly inaccurate for diatomic gases. E) A, B, and D are correct.
E
A 0.10 g honeybee acquires a charge of +23 pC while flying. Near the surface of the earth the electric field (generated by earth) is typically 100 N/C, downward. What electric field (including direction) will allow the honeybee to hang suspended in the air? A) 4.26x10^7 N/C, upward B) 4.26x10^7 N/C, downward C) 100 N/C, downward D) 100 N/C, upward E) 8.65x10^4 N/C, upward
A
A 0.10 m^3 gas tank holds 5.0 moles of nitrogen gas, at a temperature of 370 K. The atomic mass number of nitrogen is 14 and the molecular radius is 3.0x10^-10 m. The root-mean-square speed (thermal speed) of the molecules is closest to A) 570 m/s B) 410 m/s C) 99 m/s D) 810 m/s E) 22 m/s
A
Each plate of a parallel plate air filled capacitor has an area of 0.005 m^2, and the separation of the plates is 0.04 mm. An electric field of 2.7x10^6 V/m is present between the plates. What is the surface charge density on the plates? A) 24 uC/m^2 B) 51 uC/m^2 C) 12 uC/m^2 D) 36 uC/m^2 E) 60 uC/m^2
A
The figure shows four Gaussian surfaces surrounding a distribution of charges. Which Gaussian surface(s) have an electric flux of +2q/E0 through them? A) a B) b C) c D) d E) None of the surfaces
A
When two point charges are a distance d apart, the electric force that each one feels from the other has magnitude F. In order to make this force twice as strong, the distance would have to be changed to A) d/sqrt(2) B) sqrt(2d) C) d/4 D) 2d E) d/2
A
A monatomic ideal gas undergoes an isothermal a expansion at 300 K, as the volume increased from 0.03 m^3 to 0.21 m^3. The final pressure of the gas is 60 kPa. The change in the internal (thermal) energy of the gas is closest to A) 12 kJ B) 0 kJ C) 25 kJ D) -12 kJ E) -25 kJ
B
A real (non-Carnot) heat engine, operating between heat reservoirs at temperatures of 650 K and 270 K, performs 4.3 kJ of net work and rejects 8.0 kJ of heat in a single cycle. The thermal (first law) efficiency of this heat engine is closest to A) 0.38 B) 0.35 C) 0.42 D) 0.28 E) 0.31
B
A tiny object carrying a charge of +2 uC and a second tiny charged object are initially very far apart. If it takes 26 J of work to bring them to a final configuration in which the +2 uC object I is at x=1 mm, y=1 mm, and the other charged object is at x=1 mm, y=3 mm, find the magnitude of the charge on the second object.
B
If a current of 2.4 A is flowing in a cylindrical wire of diameter 2 mm, what is the average current density in this wire? A) 5.2x10^-6 A/m^2 B) 7.6x10^5 A/m^2 C) 1.9x10^5 A/m^2 D) 21x10^-6 A/m^2 E) 3.6x10^5 A/m^2
B
The electric field 3.7 cm from a very small charged object points toward the object with a magnitude of 180,00 N/C. What is the charge on the object? A) 30 nC B) -27 nC C) -30 nC D) +27 nC
B
20 g of a solid at 70 degrees Celsius is placed in a 100 g of a fluid at 20 degrees C. After reaching thermal equilibrium, the temperature is 30 degrees C. Neither the solid nor liquid has undergone a phase transition. Which statement is true? A) The specific heat of the solid and liquid are equal. B) The specific heat of the solid is less than the specific heat of the liquid. C) The specific heat of the solid is greater than the specific heat of the liquid. D) There is not sufficient information to answer the question.
C