A conducting sphere has a net charge of -6.4 × 10^-17 C. What is the approximate number of excess
electrons on the sphere? - Answers 400
An electric field in the room points from left to right. Which side of the room is at a lower potential? -
Answers Right side
Three identical light bulbs are connected to a battery as shown in the diagram. What happens when
bulb #3 burns out? - Answers Bulb 1 gets dimmer, and 2 gets brighter.
The following circuit contains two resistors and two capacitors connected to a battery through a
switch. When the switch is closed, the capacitors begin to charge up. What is the time constant for
this charging process? - Answers 0.012 s
The three loops of wire shown in the figure all hang in a region of space where a uniform magnetic
field exists everywhere out of the screen. Loop 1 swings back and forth like the bob on a pendulum,
loop 2 rotates about a vertical axis, and loop 3 oscillates up and down on a spring. An induced current
will flow around which loop or loops? - Answers Loop 2 only
What is the equivalent capacitance of the combination of capacitors shown in the circuit? - Answers
0.67 µF
Determine the power dissipated by the 40-Ω resistor in the circuit shown. - Answers 3.6 W
The figure shows the electric field lines in the vicinity of two point charges. Which one of the following
statements concerning this situation is true? - Answers The magnitude of the ratio (q2 / q1 ) is less
than one
An electron enters a region that contains a magnetic field directed into the page as shown. The
velocity vector of the electron makes an angle of 30° with the +y axis. What is the direction of the
magnetic force on the electron when it enters the field? - Answers at an angle of 30° below the
positive x axis
A long, straight wire carries a 6.0-A current that is directed in the positive x direction. When a uniform
magnetic field is applied perpendicular to a 3.0-m segment of the wire, the magnetic force on the
segment is 0.36 N, directed in the negative y direction, as shown. What are the magnitude and
direction of the magnetic field? - Answers 0.020 T, out of the paper
The magnetic flux that passes through one turn of a 13-turn coil of wire changes to 5.52 from 9.56 Wb
in a time of 0.0466 s. The average induced current in the coil is 217 A. What is the resistance of the
wire - Answers 5.19 Ohms
A long, straight wire is in the same plane as a rectangular, conducting loop. The wire carries a
constant current I as shown in the figure. Which one of the following statements is true if the wire is
suddenly moved toward the loop? - Answers There will be an induced current that is clockwise
around the loop
A circuit is pulled with a 21-N force toward the right to maintain a constant speed v. At the instant
shown, the loop is partially in and partially out of a uniform magnetic field that is directed into the
paper. As the circuit moves, a 4.0- A current flows through a 6.0-Ω resistor. What is the magnitude of
v? - Answers 4.6 m/s
A coil of wire with a resistance of 0.45 Ω has a self-inductance of 0.083 H. If a 6.0-V battery is
connected across the ends of the coil and the current in the circuit reaches an equilibrium value, what
is the stored energy in the inductor? - Answers 7.4 J
An electron moving straight upward away from the surface of the Earth passes through a magnetic
field oriented due east. What is the direction of the force that acts on the electron? - Answers Due
south
Two uncharged, conducting spheres, A and B, are held at rest on insulating stands and are in contact.
A positively charged rod is brought near sphere A as suggested in the figure. While the rod is in place,
someone moves sphere B away from A. How will the spheres be charged, if at all? - Answers Sphere A
negative, Sphere B positive
The primary coil of a transformer has 153 turns. It is connected to a standard wall outlet (V^rms = 120
V). How many turns should the secondary coil have, such that the peak voltage across it is 15,000 V? -
Answers 13,523
A long straight wire carries a current of 20 A along the positive x-axis direction. A second long straight
wire carries a current of 40 A along the positive y-axis direction. At the point (1 m, 1 m) in the xy-
plane, what is the magnitude and direction of the net magnetic field? - Answers 4.0E-6 T, into the
screen