Suppose that a picture of electric field lines is drawn following the convention that 4 field lines emerge from a small sphere with 4 pC of charge. In this picture there is an irregular closed surface, the interior of which is hidden, as shown below. The
+4 pC
Charges Q1 and Q2 are situated as shown below. The electric field is zero at point P. What conclusions can be drawn about the charges Q1 and Q2?
I. The magnitudes of Q1 and Q2 are equal.
II. The magnitude of Q1 is greater than the magnitude of Q2.
III. Th
II and IV are correct.
A positive charge is placed at one of 3 locations in a region where the electric field is uniform. Compare the magnitude F of the electric force on the charge at the different locations.
F is the same at all locations, but not zero.
A negatively charged balloon is attracted to a neutral wooden cabinet due to polarization. Which one of the following diagrams best depict why this occurs?
D
A certain physics textbook shows a region of space in which two electric field lines cross each other. We should conclude that
the author of the textbook made a mistake.
In the early universe and in stars, deuterium nuclei are produced from the combination of one proton and one neutron, with the release of a gamma ray. What is the charge on a deuterium nucleus in units of qe = 1.6*10-19 C?
1
When a positive charge is released from rest in a uniform electric field, it will
move with constant acceleration.
Two balls rest on a frictionless surface. One ball is given a charge of +Q. The other ball is given a charge of +3Q. Which diagram best represents the magnitude and direction of the force vectors on the balls?
C
Which of the following are true of static charges on everyday objects?
(a) Like charges repel.
(b) Like charges attract.
(c) Opposite charges repel.
(d) Opposite charges attract.
(e) A positively charged object has lost electrons.
(f) A positively charged
(a), (d), (e), (h) only
Through rubbing an object has acquired a charge of -1 nanoCoulomb.
Electrons have been transferred to the object.
Two uniformly charged spheres are firmly fastened to and electrically insulated from frictionless pucks on an air table. The charge on sphere 2 is three times the charge on sphere 1. Which force diagram correctly shows the magnitude and direction of the e
5
Consider the 5 arrangements of charges below. (Electric Field Hockey Simulation) Which of the following statements is true?
1) All of the pucks feel a force to the right.
2) The puck in C feels a greater force to the right than the puck in D.
3) The puck
1 and 3 only
Which of the points shown in the figure below are at the same potential?
1 and 4
Equipotential lines are shown. For which region is the magnitude of the electric field the greatest?
D
Which of the following statements about a conductor in electrostatic equilibrium is false?
(a) The electric field inside the conductor is zero.
(b) Just outside the conductor, the electrostatic field is perpendicular to its surface.
(c) The net charge ins
All the above statements are true.
Which of the following statements are true about the electric potential or the electric potential difference?
(a) The SI unit of the electric potential is volts (V).
(b) The electric potential can also be expressed in units of Joules.
(c) The electric pot
(a) and (f) only
An electron travels through free space from point A, which is at 100 V, to point B, which is at 200 V. The kinetic energy of the electron during
this trip
increases by 1.6*10-17 J
The immediate cause of many deaths is ventricular fibrillation, an uncoordinated quivering of the heart as opposed to proper beating. An electric current discharged to the chest can cause momentary paralysis of the heart muscle, after which the heart will
4472 V
A solid, conducting sphere of radius R is positively charged. Of the following distances from the center of the sphere, which location will have the greatest electric potential? (Take V = 0 at r = infinity.)
r = 0 (center of the sphere)
Equipotential lines around several point charges are shown.
What are the signs of the charges at points A and B?
The charge at B is positive and the charge at A is negative.
Equipotential lines around two point charges are shown.
What is the direction of the electric field at points A ans B?
A: to the right
B: up
A bird sits on a high-voltage line. Why does the bird not get hurt?
The whole bird is at approximately the same potential, so there is no electric field across it.
Which of the charge configurations depicted would give rise to the potential shown below?
E
Three resistors connected in series carry currents labeled I1, I2, I3, respectively. Which of the following expresses the value of the total current IT in the system made up of the three resistors?
IT = I1 = I2 = I3
A parallel combination of resistors has an equivalent (or effective) resistance of 2 ?. Which one of the following is true?
Each of the individual resistances is greater than 2 ?.
The figure below shows different ways to connect a light bulb to a battery with wires. Which of the bulbs will light up?
5
Two capacitors have an equivalent capacitance of 8 pF if connected in parallel, and 2 pF, if connected in series. Find C1 and C2.
C1 = 4 pF, C2 = 4 pF
In a series RC circuit a charged capacitor with capacitance C is being discharged though a resistor of resistance R. Plots of voltage and current versus time are shown below. Find the time constant ? of the circuit.
? = 1 s
Determine the equivalent resistance between points A and B in the following circuit.
15 k?
Two light bulbs, one rated at 50 W and a second rated at 100 W, are both supposed to be connected to a 110 V source of emf. Which one of the following is true?
The 50 W bulb has twice the resistance as the 100 W bulb.
What is the time constant for the discharge of this capacitor?
4s
In a series RC circuit a charged capacitor with capacitance C is being discharged though a resistor of resistance R. Plots of voltage and current versus time are shown below.
Image2.gif
What is the resistance of this series RC circuit?
10000 ?
The resistivity of aluminum is 58% higher than that of copper. A copper high voltage line has diameter 1 cm. If is replaced by an aluminum line of the same resistance and length, the aluminum line has diameter
1.26 cm
A bulb (i.e., a resistor) is connected in series to a switch, a battery, and an uncharged capacitor. At t = 0, the switch is closed. Which of the following best describes the brightness of the bulb as a function of time?
(c)
A series series RC circuit has a resistance of 106 ? and a time constant of 10-5 s. What is the capacitance of this circuit?
10 picoFarad
A stationary positive charge +Q is located in a magnetic field B, which is directed toward the right as indicated. The direction of the magnetic force on Q is
The magnetic force will be zero
A positive charge is moving with velocity v in a region with magnetic field B. What is the direction of the force on the particle?
into the page
Consider the situation shown below. A wire carrying a current flowing into the page is placed between the poles of a horseshoe magnet. Which statement is correct regarding the magnetic force on the wire?
The magnetic force on the wire points towards the left.
A superconducting solenoid (coil) is used to generate a magnetic field of 10 T. If the solenoid winding has 2000 turns/m, what is the required current in the solenoid?
3979A
A wire carries a current I as shown below. The magnetic field at the position P points
out of the page
A current in a long, straight wire produces a magnetic field. The magnetic field lines
form circles that go around the wire.
Which compass shows the correct direction of the magnet field at point A?
1
The paths of several particle moving through a region with a magnetic field pointing into the page are shown. Which particles are positively charged?
Particles 1 and 5
A proton is released near the equator and falls toward the earth under the influence of gravity. The magnetic force on the proton will be toward the
east
The magnetic domains in a non-magnetized piece of iron are characterized by which orientation?
They are oriented randomly.
Point P is at a perpendicular distance x from each wire carry current I in the directions indicated. What is the magnetic field B at point P?
0
What is the direction of the magnetic force on the wire segment cd?
the negative z-direction
A magnet moving past an object will produce eddy currents in the object only if the object
is a conductor
A circular loop of wire is in a region of spatially uniform magnetic field as shown in the figure.
The magnetic field is directed into the plane of the figure. If the magnetic field magnitude is constant
the induced emf is zero
A conducting rod is pulled through the magnetic field shown. Which side of the rod becomes negatively charged?
left
A loop of wire of area A is tipped at an angle ? to a uniform magnetic field B. The maximum flux occurs for an angle ? = 0o. What angle ? will give a flux that is � of this maximum value?
? = 60o
A switch is flipped and the current flowing through a wire is turned on.
A current flows momentarily clockwise in the loop.
A current-carrying wire is pulled away from a conducting loop in the direction shown. As the wire is moving away, what is the current in the loop?
A current flows clockwise around the loop
Compared to the effective resistance of two resistors connected in series, the effective resistance of the same two resistors connected in parallel is
lower
A memory cell in a computer contains a capacitor to store charge. Charge being stored or not being stored corresponds to the binary digits 1 and 0. To pack the cells more densely, trench capacitors are often used in which the plates of a capacitor are mou
5.3*10-9 m
A 9 V battery is rated at 80 Ah. It can deliver a current of 80 A for one hour, or a current of 40 A for 2 hours, etc. What is the total energy stored in the battery?
2.6 MJ
Consider a very long solenoid with radius R and length L (R << L). The magnetic field at the center of the solenoid is B0. A second solenoid is constructed that has twice the radius, twice the length, and carries twice the current as the original solenoid
2B0.
A solenoid is connected to a battery as shown. A bar magnet is placed nearby. What is the direction of the magnetic force the solenoid exerts on the bar magnet?
to the left
A proton is initially at rest at x = d and an electron is initially at rest at x = -d. At the same instant they are released. They subsequently
collide close to x = d.
A cubical closed surface has N inward electric flux lines passing through one face and N outward electric flux lines passing through the opposite face as shown in the figure.
The flux lines exhibit convergence and there are no flux lines passing through a
zero
Assume that the potential V is higher at point A than at point B. Which statement then is correct?
A positive charge gains electrostatic potential energy when it moves from point B to point A.
In the circuit shown, two capacitors and a resistor in series are connected to a battery. Initially the switch is open. What is the current through the resistor a long time after the switch has been closed?
12:00 AM
5 microCoulomb of excess negative charge is placed on a previously neutral conductor. What happens to this charge if the conductor is left undisturbed?
The excess charge distributes itself over the surface of the conductor so that the interior is free of electric fields.
A uniform magnetic field is directed into the page. A charged particle, moving in the plane of the page, follows a clockwise spiral of decreasing radius. A reasonable explanation is that
the charge is negative and slowing down.
A charged insulator and an uncharged metal
always attract one another.
In the figure below, the cube is 40 cm on each edge. Four straight-line segments, ab, bc, cd, and da form a closed loop that carries a current I = 5 A. A uniform magnetic field B = 0.02 T is in the positive y-direction. What is the magnitude of the magnet
0.057 N
The figure below shows the equipotential surfaces of an electric dipole in the xy-plane. The x and y scales are in units of meter. The charge on the left is positive. Each color change represents a a change in the potential of 5 V. Estimate the magnitude
~11 V/m to the left
A current loop lies in the xy-plane. It has a magnetic dipole moment of 0.1 A-m2 along the z-axis. A uniform 2 T magnetic field parallel to the xz-plane makes a 30� angle with the x-axis. What is the magnitude of the net torque on the current loop
0.17 Nm
Three pithballs are suspended from thin threads. Various objects are then rubbed against other objects (nylon against silk, glass against polyester, etc.) and each of the pithballs is charged by touching them with one of these objects. In one set of exper
1 and 3 carry charges of opposite sign.
Three pairs of conducting plates (capacitors) are shown in the figure below. Pair B has the same separation as pair A but twice the plate area. Pair C has the same area as pair A but half the separation between the plates. The insulating material between
C = B > A
Positive and negative charges of the same magnitude, as well as a small positive test charge are placed as shown in each of the four figures.
Rank the magnitude of the force the test charge feels in each of the four figures.
B > A > C > (D =0)
You double the voltage across a certain conductor and you observe the current increases three times. Does the conductor obey Ohm's law?
The conductor does not obey Ohm's law.
You wish to double the power dissipated by a heating device. You could
double the resistance while keeping the current the same.
If the charge on each of two identical tiny spheres is doubled while their separation is reduced by a factor of 2, their force of interaction
will increase by a factor of 16.
The SI unit of capacitance is Farad (F). This is the same as
C/V
The figure below shows the electric field lines for a system of two point charges. Point charge q2 has a charge of 2 microCoulomb. What is the charge of point charge q1?
8 microCoulomb
Two very flat, metallic plates separated a distance d have a potential difference of 600 Volts between them as shown below. A proton and positron (which is a positively charged electron) are released from rest at the surface of the metal plate held at 600
I and V only.
Which is correct language usage?
Voltage across a resistor, current through a resistor
Which one of the following best illustrates magnetic field lines associated with the bar magnets shown?
(a)