Physics 2B Winter 2012. Final Exam. Practice. 1) When the distance between two
charges is increased, the force between the charges ______. A) increases ...
Physics 2B Winter 2012
Final Exam
Practice
1) When
the distance between two charges is increased, the force between the charges ________ A) increases directly with the square of the distance. B) increases directly with the distance. C) remains the same. D) decreases inversely with the square of the distance. E) increases inversely with the distance.
2) A
circular ring of charge of radius "r" and a total charge Q lies in the x-y plane with its center at the origin. A small positive charge q is placed at the origin. If Q is negative, the direction of the force on q ________ A) is in the k direction. B) is radially inward from the ring. C) along the negative z-axis. D) has no direction since the force is zero. E) is radially outward toward the ring.
3) Two
large, flat, horizontally oriented plates are parallel to each other, a distance d apart. Half-way between the two plates the electric field field has a magnitude E. If the separation of the plates is reduced to d/2 what is the magnitude of the electric field half-way between the plates? A) E B) 0 C) 4E D) E/2 E) 2E
4) A
metallic shell of inner radius R1 and outer radius R2 carries a charge q. A point charge -q is then placed at the center of the shell. At which of the following positions, measured from the center of the shell, is the net electric field equal to zero? A) R1 < r B) E = 0 everywhere C) R1 < r < R2 D) R2 < r E) r < R1
1
5) Three
electric charges QA= q, QB = -q, and QC = -2q are located at the points A (x = + a, y = 0), B (x = -a, y = 0), and C (x = 0, y = +2a) respectively. What is the value of the electric potential at the origin? 1 q A) 4πε0 2a B) -
C)
1 2q 4πε0 a
1 q 4πε0 a
D) 0 E) -
1 q 4πε0 a
6) A
metal sphere carries an electric charge Q = +5.00 µC. The electric potential on the surface of the sphere is equal to 75.0 × 103 V. What is the magnitude of the electric field near the surface? A) 2.50 × 105 V/m B) 1.25 × 105 V/m C) 3.50 × 105 V/m D) 3.25 × 105 V/m E) 0.612 × 105 V/m
7) A
1 mF, a 2 mF, and a 3 mF capacitor are connected in parallel, the combination being connected across a 9 volt battery. The capacitor with the greatest charge on it is ________ A) the 2 mF. B) the 1 mF. C) the 3 mF. D) cannot be determined E) They all have the same charge.
8) Using
a 1 µF, 2 µF, and a 3 µF capacitor in combination, the least capacitance possible is ________ A) 0.50 µF. B) 0.25 µF. C) 0.55 µF. D) 1.0 µF. E) 0.33 µF. 2
9) A
parallel-plate capacitor has a capacitance Co with the space between the plates unfilled. If the space is now half-filled with a dielectric of constant K, the dielectric having the same thickness as the plate separation but an area of only half the area of a plate, then the new capacitance will be ________ A) KCo /2. B) 2KCo /(K + 1). C) (K + 1)Co /2. D) 2 KCo . E) KCo .
10) If
a 3.0 V potential difference causes a 0.60 A current to flow through a resistor, its resistance is ________ A) 15 Ω. B) 1.8 Ω. C) 5.0 Ω. D) 3.2 Ω. E) 0.20 Ω.
11) In
the figure below the values of the resistances are 50 Ω for resistor A, 100Ω for resistor B, and 300 Ω for resistor C. The battery has a voltage V = 5 V. What is the power delivered by the battery?
A) 0.25
W
B) 0.45
W
C) 0.15
3
D) 1.5
W
E) 2.5
W
12) For
the circuit shown in the figure below, which equation is correct for loop2 (going clockwise)?
A) E 2
+ R3I3 + E 3 + R2I2 = 0 B) E 2 + R3I3 + E 3 - R2I2 = 0 C) E 2 + R3I3 - E 3 + R2I2 = 0 D) E 2 - R3I3 - E 3 - R2I2 = 0 E) -E 2 + R3I3 - E 3 + R2I2 = 0 13) An
ideal voltmeter is one that does not change the behavior of a circuit when it is properly used to measure potential difference. The internal resistance of such a meter is ________ A) the same resistance as the circuit. B) dependent on the circuit. C) infinite. D) 0 Ω. E) cannot be determined charge q = 3 × 10-6 C of mass m = 2 × 10-6 kg, and speed v = 5 × 106 m/s enters a uniform magnetic field. The mass experiences an acceleration a = 3 × 104 m/s2. What is the minimum magnetic field that would produce such an acceleration? A) 0.001 T B) 0.01 T C) 0.004 T D) 0.1 T E) 0.04 T
14) A
4
15) A
horizontal, long current-carrying wire is hanging from a vertical thread. The current is oriented into the plane of the figure shown below. A uniform magnetic field is applied and the wire is pulled away from the vertical. Which of the arrows labeled A to D correctly indicate the direction of the magnetic field?
A) A B) B C) C D) D E) The
magnetic field is oriented into the plane of the picture.
16) The
magnetic field due to a current I in a long straight wire at a distance d is B. The magnetic field at 2d from this wire is ________ A) B/3. B) B. C) B/4. D) B/2. E) 2B.
5
17) A
toroidal solenoid has a radius R. Its cross-section has a radius r. What is the ratio of the largest magnetic field to the smallest magnetic field that exists in the solenoid when a current I is applied to its coil? B large R+r = A) B small R-r B)
B large R = B small r
C)
B large R-r = B small R+r
D)
B large (R-r)2 = B small (R+r) 2
E)
B large = r B small R
circular loop of wire of area 25 cm2 lies in the plane of the paper. An increasing magnetic field B is coming out of the paper. What is the direction of the induced current in the loop? A) counterclockwise then clockwise B) counterclockwise C) clockwise D) There is no current. E) clockwise then counterclockwise
18) A
19) If
the current increases in a solenoid, the induced emf acts to ________ A) increase the flux. B) first increase then decrease the flux. C) decrease the flux. D) have no effect on the flux. E) first decrease then increase the flux.
6
20) When
the current in an inductor triples, the energy stored ________ A) increases by a factor of 4.5. B) triples. C) doubles. D) increases by a factor of 9. E) stays the same.
21) Starting
from zero, an electric current is established in a circuit made of a battery of emf E, a resistor of resistance R and an inductor of inductance L. The electric current eventually reaches its steady-state value. What would be the effect of using an inductor with a larger inductance in this circuit? A) The steady-state value of the current would be larger, but it would take the same amount of time to reach it. B) The steady-state value of the current would be the same, but it would take more time to reach it. C) The steady-state value of the current would be the same, but it would take less time to reach it. D) The steady-state value of the current would be larger, but it would take more time to reach it. E) The steady-state value of the current would be the same, but it would take the same amount of time to reach it.
22) A
transformer changes the 10,000 V power line to 120 V. If the primary coil contains 750 turns, how many turns are on the secondary? A) 0 B) 9 C) 3 D) 6.3 × 104 E) 2.1 × 104
23) If
the frequency in an RC circuit is doubled, what happens to the capacitive reactance? A) It stays the same. B) It halves. C) It triples. D) It quadruples. E) It doubles.
24) If
the current in a 60-Hz ac circuit is given by I = Io sin ωt, what is the numerical value of ω in SI units? A) 377 B) 120 C) 200 D) 60 E) 85 7
25) An
AC source of maximum voltage V0 = 30 V is connected to a resistor R = 50 Ω, an inductor L = 0.6 H, and a capacitor C = 20 µF. What is the maximum charge on the capacitor when the frequency of the source is set to the resonance frequency of the circuit? A) 4.2 mC B) 8.4 mC C) 0 D) 2.1 mC E) 1.0 mC
8
Answer Key Testname: PRACTICE
1) D 2) D 3) A 4) A 5) E 6) B 7) C 8) C 9) C 10) C 11) A 12) C 13) C 14) C 15) C 16) D 17) A 18) C 19) C 20) D 21) B 22) B 23) B 24) A 25) D
9
