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PHYSICS 222 Fall 2008EXAM 2: November 6, 2008 8:00pm10:00pm

Name (printed): ______________________________________________Recitation Instructor: _________________________ Section #_______

INSTRUCTIONS:

This exam contains 25 multiple-choice questions plus 2 extra credit questions, each worth 3points. Choose one answer only for each question. Choose the best answer to each question.Answer all questions.

Allowed material: Before turning over this page, put away all materials except for pens, pencils,erasers, rulers and your calculator. There is a formula sheet attached at the end of the exam.Other copies of the formula sheet are not allowed.

Calculator: In general, any calculator, including calculators that perform graphing, is permitted.Electronic devices that can store large amounts of text, data or equations (like laptops, palmtops,

pocket computers, PDA or e-book readers) are NOT permitted. If you are unsure whether or notyour calculator is allowed for the exam, ask your TA.

How to fill in the bubble sheet:Use a number 2 pencil. Do NOT use ink. If you did not bring a pencil, ask for one.Write and fill in the bubbles corresponding to:- Your last name, middle initial, and first name.- Your ID number (the middle 9 digits on your ISU card) - Special codes K to L are your recitation section. (Honors section, please enter 24).

Always use two digits (e.g. 01, 09, 11, 13)

Please turn over your bubble sheet when you are not writing on it.

If you need to change any entry, you must completely erase your previous entry. Also, circleyour answers on this exam. Before handing in your exam, be sure that your answers on yourbubble sheet are what you intend them to be. You may also copy down your answers on a pieceof paper to take with you and compare with the posted answers. You may use the table at theend of the exam for this.

When you are finished with the exam, place all exam materials, including the bubble sheet, andthe exam itself, in your folder and return the folder to your recitation instructor.

No cell phone calls allowed. Either turn off your cell phone or leave it at home. Anyoneanswering a cell phone must hand in their work; their exam is over.

Best of luck, Paul Canfield and Paula Herrera.

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28.A monatomic, ideal gas is in a sealed container (the number of gas molecules isalways constant: n = 4 moles); the initial pressure isPi = 1.01 x 10

5Pa and the

initial volume is Vi = 0.02 m3. The gas is compressed at a constant pressure to a

final volume ofVf= 0.01 m3. What is the heat transfer in this process?

A) 2525 J released by the gasB) 1010 J released by the gasC) 0 JD) 1010 J absorbed by the gasE) 2525 J absorbed by the gas

29.A magnet moves toward a circular copper wire loop, perpendicular to the page,as shown in the figure. Which of the following statements is false?

S Nv

P

A) The current induced in the wire runs clockwise as seen from point P.B) An electric field is induced in the wire.C) The magnetic moment induced in the loop points to the left.D) The magnitude of the magnetic flux through the loop due to the magnet is

increasing.E) All of the above are true.

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The situation below pertains to the next two questions:

Three moles of an ideal diatomic gas are compressed adiabatically to 1/20 of their initial

volume. The gas was initially at room temperature (20C).

30.The final temperature of the gas is closest to:

A) 15CB) 66CC) 88CD) 700CE) 1900C

31.What is the change of entropy in the gas in the previous problem?

A) 100 J/K

B) 24 J/KC) 0D) 24 J/KE) 100 J/K

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32.Which of the following statements is true?

A) The entropy of a system can never decrease.B) The entropy of a system can never decrease if the process is reversible.

C) All the processes in a Carnot cycle are reversibleD) The heat exchange during a reversible process is always zero.E) The internal energy of a system remains always constant during a reversible

process.

33.At t= 0, a proton with speed 30,000 m/s in the +x direction is in a region with auniform magnetic field of 1.2 T in the +y direction. What is the kinetic energy of

the proton at t= 1.0 ms? (mass of the proton = 1.671027

kg; charge of the

proton = 1.61019

C).

A) 1.81020 J

B) 3.41020 J

C) 1.01019 J

D) 4.51019 J

E) 7.51019 J

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I

B

30

The situation below pertains to the next two questions:

A square loop (side 20 cm) with a current of 0.3 A running

in the clockwise direction is in the plane of this page. There

is a uniform magnetic field of 2.0 T parallel to the page butat an angle of 30 with the horizontal direction.

34.What is the magnitude and direction of the magnetic force on the right side of thesquare?

A) 0.060 N into the pageB) 0.060 N out of the pageC) 0.10 N into the page

D) 0.10 N out of the pageE) 0

35.What is the magnitude of the torque on the loop?

A) 0B) 0.012 N mC) 0.021 N mD) 0.024 N mE) 0.048 N m

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IThe situation below pertains to the next two questions:

A solenoid of length 80 cm and radius 4.0 cm is made with a total of

150 turns of wire. The current in the solenoid is 0.28 A. The figure

shows the solenoid as seen from one of its ends.

36.What is the magnetic field at a point on the axis of the solenoid and in the centralregion of the solenoid (far from the ends)?

A) 5.3105 T into the page

B) 5.3105 T out of the pageC) 0

D) 6.6 105 T into the page

E) 6.6105 T out of the page

37.If the current was doubled, the energy stored in the solenoid would change by a

factor of:

A) 1/4B) 1/2C) 1 (no change)D) 2E) 4

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The situation below pertains to the next two questions:

A 5.0 cm 15 cm rectangular loop of wire with a total resistance of 40 is orientedperpendicular to thezaxis. Before time t= 0, a 5 T uniform magnetic field exists inthe +zdirection (into the page) as shown in the figure. For all other times, the strength

of the field is given by the curve to the right.

38.What is value of the magnetic flux through the loop at time t= 0.5 s?

A) 0.32 mWbB) 4.2 mWbC) 8.4 mWbD) 21 mWbE) 38 mWb

39.Calculate the magnitude of the current at t= 4.5 s.

A) 0.21 mAB) 1.9 mAC) 9.0 mAD) 15 mAE) 35 mA

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40.A closed rectangular loop of wire with a light bulb is pulled at constant speed inthe +x direction through the region shown in the figure. The magnetic field is

pointed in the positivezdirection and is non zero in the region betweenx = 0 andx = a and is zero outside of this region. The loop enters the field region at t= 0.

What does the light intensity from the lamp look like as a function of time?

t

IntensityA)

t

IntensityB)

IntensityC)

IntensityD)

Intensity

E)

v

y

xa

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41.A solid wire with a circular cross-section of radius 30 mm carries a total currentof 10 A out of the page. The current density across the wire is uniform. What is

the magnetic field at a point 15 mm away from the center of the wire?

A) 0B) 0.015 mTC) 0.033 mTD) 0.13 mTE) 0.17 mT

42.A Carnot engine would have the largest efficiency for which of the following

values ofTC and T= TH TC?

A) T= 500 K TC = 500 K

B) T= 100 K TC = 300 K

C) T= 60 K TC = 20 K

D) T= 5 K TC = 20 K

E) T= 1 K TC = 2 K

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43.Imagine a wire loop running along the edge of this paper carrying a current in aclockwise direction around its perimeter. If there is a uniform magnetic field

applied perpendicular to (and out of) this page, the interaction between the field

and the current will:

A) Do nothing at all, there will be none.

B) Tend to pull the wires inward.

C) Tend to push the wires apart.D) Tend to rotate the loop around an axis through the center of the page and parallel

to the top edge of the sheet.

E) Tend to rotate the loop around an axis through the center of the page and parallelto the left edge of the sheet.

44.The figure shows the paths of four particles. They all have the same charge q andinitial speed v. They are in a region of uniform magnetic field out of the page.

Which particle has the largest mass?

A) A

B) BC) C

D) DE) Cannot be determined from data given.

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45.After one complete cycle of a Carnot engine operating between TH > TC, whichof the following quantities is NOT zero?

A) Sof the working gas.

B) p of the working gas.C) Wdone by the working gas.

D) Tof the working gas.

E) Uinternal of the working gas.

46.The magnetic force on a charged particle is in the direction of the particlesvelocity if:

A) It is moving in the direction of the magnetic field.B) It is moving in the direction opposite to that of the magnetic field.

C) It is moving perpendicular to the direction of the magnetic field.

D) It is moving in a circular path.

E) Never.

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47.You put 500 g ofT= 0C water into your freezer. If this unit has a coefficient ofperformanceK= 3.0, how much heat will be dumped into your room as a result

of freezing this water to T= 0C ice?

A) 5.5 10

4

JB) 1.1 10

5J

C) 1.6 105

J

D) 2.2 105

J

E) 6.6 105

J

48.An electron has a velocity of 20 m/s in the directionperpendicular to the page (coming out of the page).

It is in a region of constant and uniform electric and

magnetic field, as shown below in the figure. What

is the total force on the electron (ignoring gravity)?

A) 9.6 1019

N up

B) 9.6 1019

N down

C) 2.2 1018

N up

D) 2.2 10

18 N downE) 3.5 10

17N down

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49.Two very long wires carry 2 A and 4 A currents as shown. What is themagnitude and direction of the magnetic field at a point located halfway betweenthe two wires?

A) 1.2 106

T into page

B) 1.2 106

T out of pageC) 0 T

D) 4.0 107

T into page

E) 4.0 107

T out of page

50.One mole of ideal, monatomic gas has an initial temperature and volume ofTi

and Vi. If the gas is heated isochorically to Tf= 2Ti (with the process being donequasi-statically), what is the change in entropy of the gas?

A) 16.6 J/K

B) 12.5 J/K

C) 8.65 J/K

D) 6.23 J/KE) 4.32 J/K

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51.Two very long, vertical, current carrying wires intersect thex axis at 4 cm and+4 cm as shown. At which point will the magnetic field have the largest

magnitude?

A) A

B) BC) C

D) DE) E

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52.An ideal solenoid is 10 cm long, has a cross sectional area of 20 cm2, and has a0.15 T field at its center when a 10 A current flows through it. What is the self

inductance,L, of this solenoid?

A) 36 mHB) 360 mH

C) 720 mH

D) 3.6 HE) None of the above

53.A battery with potential V0, a switch, a 250 Ohm resistor and an inductor,L,form a single loop, seriesL-R circuit. If you want the current to rise to 0.85 V0/R

2.00 ms after the switch is closed, what value does L need to have?

A) 0.725 H

B) 0.500 H

C) 0.437 HD) 0.327 H

E) 0.264 H

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54.Two coils 1 and 2 are coaxial located next to each other. If the current in coil 1changes with time as shown in the figure below, which of the graphs correspondsto the emf in coil 2?

t

i1

t

2

A)

t

2

B)

t

2

C)

t

2

D)

t

2

E)

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You may record your answers on this page and take it with you after the exam to

compare to the posted solutions.

28 38 48

29 39 49

30 40 50

31 41 51

32 42 52

33 43 53

34 44 54

35 45

36 46

37 47