please read all instructions before beginning

S. Rekrut, L. Richards 3 Hours

PHYSICS 40S F I N A L E X A M January 1998 1 of 12 pages

Instructions for Students

Please read all instructions before beginning.

1. Check all pages to ensure there are no blank or illegible pages in this booklet. 2. This page is the your answer sheet for all multiple choice questions. Remove it from the booklet, place

your name at the top and record answers in the appropriate spot. 3. An equation sheet is provided for your reference. It is the last page. 4. Part C contains long answer questions. Be sure to show all your work as part marks will be awarded for

all questions. 5. Please place your name at the top of all sheets that you have used for answering questions. 6. At the conclusion of the exam, write your name and your teacher's name on the reverse side of the exam

Turn upside down and leave all papers on your desk. 7. I f you have any questions please ask!!! 8. You have 3 hours to complete this exam.

Good Luck

Name Teacher

1 26 51 _ Totals 2 27 52 " Part A 3 28 _ 53 Part B 4 29 54 ______ PartC 5 30 55 ______ 6 31 56 Exam %

7 — 32 ~~ ~ 57 8 33 58 9 34 59 10 35 60 11 36 61 12 37 62 ^ 13 38 63 " 14 39 _ _ _ _ _ 64 15 40 65 ' 16 ~~ 41 66 17 42 67 18 " 43 68 19 44 * 69 20 45 '~_ 70 ' 21 " 46 71 22 ~ 47 72 23 48 73 ^ _ 4 Q 74

P H Y S I C S 40S F I N A L E X A M S. Rekrut, L. Richards 3 Hours

Part A Multiple Choice A l l questions in this part are worth 1 mark.

January 1998 2 of 12 pages

Select the BEST answer for each of the following statements. Record your answer on the answer sheet that has been provided.

1. The charge on two charged objects is held constant while the distance between doubled. The Coulomb Force between them is; a. doubled b. halved c. quartered d. remains the same.

Examine the following diagram in which two smalt spheres have equal charges and are separated by a distance d. The force exerted on each sphere by the other has a magnitude Fo. I f the charge on each sphere is doubled and the distance between them is halved, then the resulting force on each has a magnitude of, a. F b. 2F c. 4F & 8F e. 16F

® ® A device commonly used to detect the presence of static electric charge is the; a. electrophorus b. electroscope c. galvanoscope d. spectroscope

Electric field lines; a. originate on negative charges b. terminate on positive charges

c. terminate on negative charges d. cross in space

5. An electric field exists between two plates as in the diagram. The charges on the plates are;

Plate A Plate B A Negative Positive B Negative Negative C Positive Negative D Positive Positive

E

An uncharged metal ball is electrically; a. repelled by a charged glass rod b. repelled by a charged rubber rod

S

c. attracted by a charged glass rod d. unaffected by a charged rod

7. When a charged object is brought near an electroscope, the leaves collapse. The net charge on the object i s ; a. negative b. neutral c. positive d. unknown

8. The electric field in the vicinity of two point charges is equal to the; a. algebraic sum of the fields. c, field created by the positive charges only. b. differences of the individual fields. d. vector sum of the individual fields.

9. At a point midway between two equal point charges, the electric field is; a. zero. c. is at a maximum. b. has only magnitude. d. has only direction.

10. A point charge is placed in an electric field that varies with position. No electric force is exerted on the charge; a. i f it is completely surrounded by other charges. b. at positions where the electric field is zero. c. When it is moving parallel to the electric field. d. When it is moving perpendicular to the electric field.

11. A negatively charged object is placed midway between two oppositely charged plates as in the diagram. The electric force on the charge is;

a. directed toward the positive plate. b. zero. c. directed toward the negative plate. d. directed parallel to the plates.

12. Increasing the length of a conductor wi l l ; a. cause its resistance to increase.

********* B

PHYSICS 40S F I N A L E X A M S. Rekrut. L Richards 3 Hours

January 1998 3

14. The resistance of a length of copper wire is R. The resistance of a piece of copper wire the same length but having twice the diameter is: a. R b. 2R c 4R d R/2 e. R/4

15. In most areas of Canada and the United States the frequency of A C electrical system is: a. 30 Hz b. 50 Hz c. 60 Hz d. 90 Hz c. 120 Hz

16. The voltage produced by two identical batteries is at a minimum; a. when the batteries are connected in parallel b when the batteries are connected in series c. regardless of how the batteries are connected.

17. The voltage across a resistor in a simple circuit is most directly a measure of; a. electric field m the resistor b. force in Newtons tending to accelerate a unit charge in a resistor c. resistivity of the resistor material d maximum temperature the resistor can attain e. total energy expended by a unit charge moving through the resistor

18. A metallic conductor would pass current less easily i f its; a. cross sectional area were increased b. Length were decreased. c. Temperature were increased. d. Temperature were decreased.

19. I f the current in a circuit is doubled and the resistance is halved, the heat produced in the resistance; a. decreases b. increases c. remains the same

20. Electric energy can be expressed in terms of a. Amperes b. Coulombs c. Watts d. Watt-seconds

21. The relationship between applied voltage and current flow in many common conductors is given by; a Ampere's Law b. Coulomb's Law c. Kirchhofrs Law d Ohm's Law

22. Current in a conductor is due to the movement of, a. electrons b. neutrons c. nuclei d. protons

23. Which of the following is the best conductor of electricity at room temperature? a. Aluminum b. Copper c. Pure water d. wax

24. Which of the following graphs best describes the potential differenceas a function of the current for a light bulb.

a I b II c. I l l d IV e. V

25. Conductor (I) has a length (L) and a cross-sectional area (A). Conductor (II) lias a length (2L) and a cross-sectional area (2A). I f both conductors have the same resistivity; a. Both conductors have the same resistance b Conductor (I) has more resistance than conductor (II). c. Conductor (II) has more resistance than conductor (1) d. Resistance depends only on the conductor's mass

26. The statement of the conservation laws of charge and energy for electric circuits is attributed to, a. Ampere b. Coulomb c. Kirchhoff d Ohm

27. A straight conductor carrying a current is perpendicular to a uniform magnetic field. The direction of the magnetic force acting on the conductor may be reversed in direction; a. By reversing the direction of both current and field b By reversing the direction of either the current or the field. c. ' Only by reversing the direction of the current. d. Only by rev ersing the direction of the field.

A unifnrm maonrfr f i f lH (R\ is nernendicular to and points into the page, as x X x x


P H Y S I C S 40S F I N A L E X A M January 1998 4 of 12 pages

2

R

2r 3r

i

29. A long straight conductor carries a constant current (I) as shown in the diagram. I f the magnitude of the magnetic field at point Q is (B), the magnitude of the field at point P is; a. B b. 2B c.4B d. B/2 e. B/4

30. I f the magnetic domains of a bar of iron are randomly orientated, the iron bar wi l l ; a. be repelled by a permanent magnet. b. Have a very weak or non-existent magnetic field. c. Be strongly magnetized. d. Line up in a north-south direction when

suspended from a string.

31. A magnetic field wi l l exert no force on a current carrying conductor when the angle between the conductor and the magnetic field is;

a. 0 degrees b. 30 degrees c. 60 degrees d. 90 degrees

32. The electric field between two parallel plates is perpendicular to a magnetic field, which is directed out of the page. A particle with a positive charge enters the field with a velocity (v), perpendicular to both the magnetic and electric fields. I f the electric force on the particle is greater than the magnetic force, the particle's path is best represented by; a. Path I b. Path I I c. Path I I I

33. An important distinction between electric field lines and magnetic field lines is that; a. Electric field lines never terminate. b. Electric field lines are only found around electric currents. c. Magnetic field lines always form closed loops. d. Magnetic field lines can be produced with any electric charge.

34. The experiment that demonstrated the connection between electric currents and magnetic fields was first conducted by;

a. Ampere b. Gauss c. Oersted d. Ohm e. Volta

35. A single loop of wire lies in the x-z plane as shown in the diagram. A conventional current flows through the loop as shown. The magnetic field at point S points in the;

a. + x direction. b. - x direction. c. + y direction. d. - y direction. e. + z direction. f. - z direction.

36.

s

i R

I f the resistive load is A resistive load is connected across the secondary windings of a transformer, decreased more current wi l l flow in;

a. The primary only b. The secondary only. c. Both the primary and the secondary. d. Neither the primary nor the secondary.

37. A conducting rod lies on two horizontal parallel rails at a distance (L) apart. A magnetic field lies perpendicular to and points into the page. A resistor of resistance ( R ) is connected between the two rail. A current (I) is induced in the rod when it moves with constant velocity (v). The following expression represents;

IR BL

a. The rate at which the flux in the loop changes.

b. The power dissipated by the resistor.

X X

X X

X

PHYSICS 40S F I N A L E X A M S. Rekrut, L. Richards January 1998 3 Hours 5 of 12 pages

39. Consider the following statements:

I . A changing magnetic field can induce a current to flow in a stationary piece of wire. I I . The emf induced in a circuit is proportional to the magnetic flux through the circuit

a. Both statements are false. b. Both statements are true. c. Only statement I is true, d. Only statement I I is true.

40. Two closed circuit loops are close to one another. The loops are magnetically linked, but not electrically connected. As the current in the first loop increases at a constant rate;

a. A constant current flows in tbje second loop. b. A decreasing current flows in the second loop. c. An increasing current flows in the second loop. d. No current flows in the second loop.

41. An. emf (e) is induced in a coil when the magnetic flux changes from <t> to 2 # in a time At. I f the change in magnetic flux had been O to 3C> in a time of At, the induced emf (e) would have been;

a. 2e b. 3e c. e/2 d. s/3

42. As a conductor moves perpendicular through a magnetic field with increasing speed, the emf induced in the conductor;

a. decreases. b. increases. c. remains the same.

43. The direction of an induced emf which results from a changing magnetic flux may be determined by using;

a. Ampere's Law b. Faraday's Laws c. Gauss's Law d. Lenz's Law

44. The emf induced in a conductor as it moves across a magnetic field depends on; a. The diameter of the wire. b. The conductivity of the conductor. c. The speed of the conductor. d. The resistance of the conductor.

45. During a time equal to the period of a certain tuning fork, the emitted sound wave travels a distance; a. Of one wavelength b. Equal to about 330 m. c. Proportional to the intensity of the waves. d. Equal to the length of the tuning fork. e. Directly proportional to the frequency of the tuning fork.

46. Waves transmit a. amplitude b. energy c. mass d. wavelength

47. The period of a wave is the a. Inverse of the amplitude b. Inverse of the frequency. c. Inverse of the mass. d. Inverse of the intensity. e. Number of vibrations per second.

48. A transverse pulse traveling down a string, as in the diagram, is reflected from an end attached to a wall. The reflected wave;

a. Changes its speed. b. Undergoes no change in phase. c. Undergoes no change in speed. t$? d. Undergoes a change in frequency.

49. The principle of superposition states that; a. Diffraction depends on the ratio of wavelength to slit width. b. Points on a wave front may be considered point sources. c. The amplitudes of waves that coincide at a point may be added, d. The wavelength of an incident wave equals that of a reflected wave.

50. When a transverse pulse, which is traveling on a string, reaches the junction of a lighter string, the pulse

PHYSICS 40S FINAL EXAM S. Rekrut, L. Richards 3 Hours

January- 1998 6 of i ; pages

Part B - Multiple Choice All questions in this part are worth 3 marks.

51. What is the gain in kinetic energy i f an electron is accelerated through a distance of 0.20 m across a

potential difference of 5.0 x 10 W?

a. 1.6x 10" 1 7 J c. 8.0x10 4 7 J

b. 4.0 x 10 1 6 d. 5.0 x 10 2 J

52. What is the number of protons that will leave a cyclotron each second i f the beam of high speed protons

is equivalent to a current of 3.2 x 10 ' A? 16 _ , - 2 i

a. 2 .0x10 c. 2.0x10 b. 6 .3x10 1 6 d. 5.1x10 2 2

-3

53. An electron passes between two parallel plates that are 5.0 x 10 m apart and have a potential

difference of 4.0 x 10 3 V between them. What is the magnitude of the force that acts on the electron?

a. 1 . 3 x 1 0 , 6 N c. 1 . 3 x l O " 1 3 N

b. 6.4 x 10 , 6 N d . 6 . 4 x 1 0 ~ 1 3 N

8 54. An insulated metal block is originally neutral. What wil l be the resulting charge i f 1.5 x 10 electrons

are removed from the block? a. 2.4 x 10 " ~ 2 7 C c. + 2.4 x 10 ~"27 C

b. ~ 2.4 x 10 _ I 1 C d. -2.4 x 10 ~ n C

55. Two charged bodies repel each other with a force of magnitude F. The charge on one is then doubled, the charge on the other is increased by a factor of 7/3, and the distance between them is tripled. What will be the resulting force between them?

a. F/9 ' b. 14 F/27 c. 14 F/3 d. 42 F

56. Two parallel plates are separated by a distance of 4 mm and connected to a 300 V source. What is the electric field between the two plates?

a. 1.33 x 10 " 5 N/C c. 3.00 x 1 () 2 N/C

b. 1.20 x 10° V/m d. 7.50 x 10 4 N/C

57. What is the resistance in a circuit i f a current of 0.50 A exists when a potential drop is 12 V? a. 0.042 f2 b. 3.0 Q c. 6.0 Q d. 24.0 Q

58. The power dissipated by a certain resistor is P. What wil l be the power dissipated i f the potential difference across the resistor is doubled?

a. %A P b. '/2 P c. 2 P d. 4 P

59. An electric motor connected to a 100 V supply draws a current of 25 A. What will be the cost of running the motor for 4.0 hours i f the cost of electricity is 7.0 e/kWh?

a. $0.07 b. $0.28 " c. $0.70 d. $1.12

60. Examine the circuit diagram to the right. Determine the

reading on meter A3 j f the battery supplies a potential

difference ° f 18 V. a. 9 V b. 18 V c. 3A d. 9 A

61. Examine the circuit diagram below. Determine the change in total resistance of the circuit when the switch is closed. Note the battery wil l supply a potential difference of 45 V.

X T

100 I k a. I Q

6 0 § I 2 0 0 b 2 Q f 0 c 3 O

S d 4 H J


PHYSICS 40S F I N A L E X A M January 1998 7 of 12 pages

64. Determine the current is a long straight wire that produces a magnetic field of magnitude 1.0 x 10 6 T 4

cm away from the wire. a. 0.05 A b. 0.2 A c. 5.0 A d. 20.0 A

65. A wire 4cm long is placed at 40 to a uniform magnetic field of strength 0.5 T. I f the wire carries a current of 0.32 A, determine the magnitude of the magnetic force on the wire.

a. 4.1 x 10" 3 N b. 4 . 9 x l O " 3 N c. 6.4 x 10* 3N d. 6 4 x 1 0 * ' N

66. Two parallel wires are 10 cm apart and carry currents of 20 A each in the same direction. What is the force per metre of length each wire exerts on the other wire?

a. 8.0 x 10" 4 N Repulsive c. 8.0 xlO* 4 N Attractive

b. 8.0 x l O ^ N Repulsive d. 8.0 x 10"6 N Attractive

67. The diagram below shows a portion of a rope in which a disturbance MN travels in the direction of the arrow.

Which one of the following configurations of the rope could NOT appear i f the disturbance M N meets a similar disturbance PQ traveling in the opposite direction?

A)

B )

68. A proton is accelerated from rest through a potential difference of 90 V and emerges with a speed of 1.3 5 -1 - l

x 10 ms . The proton then enters perpendicularly into a uniform magnetic field of strength 2.0 x 10 * T. What wi l l be the radius of the circular path of the proton in this magnetic field?

a. 2.8 x 10 m b. 0.068 m c. 0.14 m d. 0.24 m

69. A 15 cm long wire moves a constant speed of 7.2 ms 1 perpendicular to a magnetic field of strength 0.24 T. What is the potential difference across the ends of the wire?

* S 0 x 10"3 V b. 0.26 V c. 3.9 V d. 25.9 V


72. A coil of 650 turns experiences a change in flux linkage of 1.15 x 10 5 Wb in 2.00 ms. What is the induced emf?

a. 0.374 V b. 3.74 V c. 37.4 V d. 678.0 V

73. A train is moving directly south with a uniform speed of 10 ms 1 . I f the vertical component of the earth's

magnetic flux is 5.4 x 10 5 T, compute the emf induced in a car axle 1.2 m long.

a. 3 . 2 x 1 0 % 4 . 8 x 1 0 " % c. 6 . 5 x 1 0 " % d. 7 . 3 x 1 0 %

74. A light ray is incident on a glass to air surface. The index of refraction of the glass is 1.414. within 1 %, The critical angle, in degrees, for this surface is :

a. 24 b. 30 c. 45 d. 60

75. What is the frequency of red light of wavelength 632 nm.

a. 4.75 x 1 0 1 4 H z b. 6.3x10 1 5 Hz c. 2.1 x 10" 1 5 Hz d. 4.75 x 10 1 6 Hz

Part C Long Answer Questions

Answer all the following questions in the space that is provided.

76. In the diagram below a straight pulse moves towards a straight barrier at a speed of 1 cm/s. Draw the pulse and indicate the direction of propagation of the pulse 5 seconds later.

BARRIER

A T 1

PULSE

77. A physics student has available an insulated rod carrying a large positive charge and two identical neutral

metal spheres on insulated stands. Describe a process that may be used to charge the spheres such that

one sphere is charged negatively and the other sphere is charged with an equal positive charge.

00 + +

Insulated Charged Rod

+- +• +

PHYSICS 40S FINAL E X A M S. Rekrut, L. Richards January 1998 3 Hours 9 of 12 pages

78. Three charges are located on a plane as in the diagram ^

below. I f Ql " 4 85 nC, Q2 = + 55nC, and Q3 - -70 nC, 3 m ~Q2

determine the magnitude and direction of the

electrostatic force acting on Q j .

O Q 3

PHYSIC'S 40S F I N A L E X A M S. Rekrut, L. Richards - January 1998 3 Hours • 10 of 12 pages

79. Examine the circuit diagrams below. Which schematic could be used to correctly investigate Ohm's

Law? Describe what measurements would be taken and how these could be analyzed in verifying the

Law.

0 r - — , B)

<2> — ® _ J . . . J

PHYSICS 40S F I N A L E X A M S. Rekrut, L Richards 3 Hours

January 1998 11 of 12 pages

80, A battery with an emf of 75 V is connected to a circuit that has four 15 O resistors

a. Draw a schematic to illustrate these resistors arranged in a circuit that has the maximum

resistance possible. Determine the current through each resistor.

b. Draw a schematic to illustrate an arrangement that would produce a total resistance of 25 O.

Determine the current through each resistor.


3 -1

81. An alpha particle (m= 4x nip, Q = +2e) is traveling at 4.7 x 10 ms north, when it enters a uniform,

magnetic field of strength 0.275 T as shown below.

X X X X X

X X X X X

X X X X X

X X X X X

X X X X X

t 0

a. What is the force on the alpha particle?

b. What is the radius of the resulting circular path of the particle?

c. On the diagram, sketch the resulting path of the alpha particle in the field.

82. A transformer has 520 turns of wire in the primary coil and 230 turns in the secondary coil. A potential

difference of 120 V is applied to the primary coil which results in a secondary airrent of 2.0 A.

a. What is the secondary voltage?

b. What is the primary current?

r v«i«ir» t i / K t / #»i**r»tric nnww transmission is done at very high voltage.

PHYSICS 40S F I N A L E X A M S. Rekrut, L. Richards 3 Hours

January 1998

PHYSICS 300 CONSTANTS

Coulomb's constant, k 9.0 x 10* N "

Charge on an electron, e 1.60 x 10"19 C

Mass of proton, m, 1.67 x 10 ~ 2 7 leg

Mass of electron, m6 9.11 x 10' 3 1 kg

Vacuum permeability, u 0 4 rt x 10"7 - ~

Ampere's constant, k 2.0 x 10"7 —

Acceleration due to gravity, g 9.8

Permittivity of free space, € 0 8.85 x 10"12 — OR — Jm s i


PHYSICS 40S F I N A L E X A M January' 1998

PHYSICS 300 FORMULAE

v = Xf

r

P - 1 2 E

P = ~ t

A

C

C » 2ni * «d

C = K c 0 A

# - BA

_ B = 2 L L

Ho1 kl E = M B

F - B I L - BILsinO W * q V

= mg F = q v B L = qvBsinS

V - Ed _ m v 2

F = — —

P - V I

u 0 L I 2 L k l ^ L V = I R F » —

€ -

t

At

R € - B L v

W V 0 N

V N

A « i r r 2

_£ V 0 = # V

V

I 0 - V5l

NOTE: Electron flow means a current of negative charges. C o n v e n t i o n a l c u r r e n t means a f l o w o f pos i t ive charges .

please read all instructions before beginning

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