Physics 2 Exam 3 - Quizzes - Ch 16, 17, & 18
For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?
(current)-1
For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?
(current)-1
Which vector best represents the direction of the electric field at the fourth corner of the square due to the three charges shown in Fig. 16-51?
(d)
For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?
(potential)-1
For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?
(resistance)-1
Which one of the following quantities is equivalent to 1 W?
1 V ∙ A
Which one of the following quantities is equivalent to 1 Ω?
1 V/A
During a period of high power demand, the voltage output of the power company is reduced by 5.0%. By what percentage is the power in a ohmic device decreased?
10%
The potential (relative to infinity) at the midpoint of a square is 3.0 V when a point charge of +Q is located at one of the corners of the square. What is the potential (relative to infinity) at the center when each of the other corners is also contains a point charge of +Q?
12.0 V
A small charged plastic ball is vertically above another charged small ball in a frictionless test tube as shown in the figure. The balls are in equilibrium a distance d apart. If the charge on each ball is doubled, the equilibrium distance between the balls in the test tube would become
2d
A kilowatt-hour is equivalent to
3,600,000 J.
If it takes an amount of work W to move two +q point charges from infinity to a distance d apart from each other, then how much work should it take to move three +q point charges from infinity to a distance d apart from each other?
3W
The electric potential at a distance of 4 m from a certain point charge is 200 V relative to infinity. What is the potential (relative to infinity) at a distance of 2 m from the same charge?
400 V
Four point charges of equal magnitude but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the center charge?
A
Four point charges of equal magnitudes but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the center charge?
A
Four point charges of varying magnitude and sign are arranged on the corners of the square of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the point charge with a charge +Q?
A
Three equal positive point charges +q are placed at the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the center of the square?
A
Three equal-magnitude point charges of varying signs are placed at the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the center of the square?
A
Which one of the arrows shown in the figure best represents the direction of the electric field between the two uniformly charged metal plates?
A
A conductor is placed in a steady external electric field. Which of the following statements are correct for this situation?
All of the above statements are correct.
Which are unsafe places to be during a lightning storm?
All of the above.
Three equal charges +Q are at three of the corners of a square of side d. A fourth charge +Q of equal magnitude is at the center of the square as shown in the figure Which one of the arrows shown represents the net force acting on the charge at the center of the square?
B
Three equal negative point charges -q are placed at three of the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the vacant corner of the square?
B
Three equal-magnitude point charges of varying signs are placed at three of the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the vacant corner of the square?
B
A proton (Q = +e) and an electron (Q = -e) are in a constant electric field created by oppositely charged plates. You release the proton from near the positive plate and the electron from near the negative plate. Which one has more kinetic energy at the moment of collision with the opposite plate?
Both acquire the same kinetic energy.
Three equal negative point charges -q are placed at three of the corners of a square of side d as shown in the figure. Which one of the arrows shown represents the direction of the net electric field at the center of the square?
C
Two small identically charged balls are a certain distance apart. The vectors in the figure show the magnitude and direction of the electrostatic force on each ball due to the other one.Suppose that the charge on the left ball is now doubled (represented by two plus signs). Which vector diagram below best represents the forces that now act on each of the two balls?
C - ++ +in equal amount
Two equal and opposite charges are a small distance apart, forming an electric dipole. A positive charge +q is placed above these charges, as shown in the figure, equidistant from both of them. Which diagram below best gives the direction of the net force the dipole exerts on the charge +q?
C - pointing to the right
Four point charges Q of equal magnitude and sign are arranged on three of the corners of the square of side d as shown in the figure Which one of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?
D
Four identical point charges are arranged at the corners of a square [Hint: Draw a figure]. The electric field E and potential V at the center of the square are
E = 0, V ≠ 0.
Which of the following is a vector?
Electric field.
Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F0 due to the other. With time, charge gradually diminishes on both spheres by leaking off. When each of the spheres has lost half its initial charge, what will be the magnitude of the electrostatic force on each one?
F0/4
Electrically neutral objects cannot exert an electrical force on each other, but they can exert a gravitational force on each other.
False
Which of the following statements is valid?
If the potential throughout a particular region is constant, the field throughout that region must be zero.
Swap the positions of Q1 and Q2 of MisConceptual Question 1. Which of the following is true of the force on Q1 due to Q2?
It changes from the +x direction to the -x direction.
Q1 = - 0.10 µC is located at the origin. Q2 = +0.10 µC is located on the positive x axis at x = 1.0 m. Which of the following is true of the force on Q1 due to Q2?
It is attractive and directed in the +x direction.
Where in the circuit of Fig. 18-33 is the current the largest?
It is the same at all points.
Two point charges, Q1 and Q2, are separated by a distance R. If the magnitudes of both charges are doubled and their separation is also doubled, what happens to the electrical force that each charge exerts on the other one?
It remains the same.
Two point charges, Q1 and Q2, are separated by a distance R. If the magnitudes of both charges are halved and their separation is also halved, what happens to the electrical force that each charge exerts on the other one?
It remains the same.
In outer space, a positive charge q is released near a positive fixed charge Q, as shown in the figure. As q moves away from Q, what is true about the motion of q?
It will move with increasing speed.
When current flows through a resistor,
Neither a. nor b. is true.
Electrons carry energy from a battery to a lightbulb. What happens to the electrons when they reach the lightbulb?
None of the above.
When you double the voltage across a certain material or device, you observe that the current increases by a factor of 3. What can you conclude?
Ohm's law is not obeyed.
Which of the following statements about Ohm's law is true?
Ohm's law relates the current through a wire to the voltage across the wire.
The figure shows electric field lines arising from two small charged particles P and Q. Consider the following two statements:(i) The charge on P is smaller than the charge on Q.(ii) The electrostatic force on P is smaller than the force on Q.Which of the above statements are true?
Only (i) is true.
Two very small plastic balls of equal mass are released from rest. One of them carries +10 µC of excess charge and the other one carries +1 µC of charge. No other charges or fields are present. Which of the following statements are true about them as they move away from each other?
The balls have accelerations of equal magnitude.
The figure shows conventional current passing through a resistor. The arrow shows the direction in which this conventional current is flowing. Which of the following statements are correct?
The current at point b is the same as the current at point a.
Why might a circuit breaker open if you plug too many electrical devices into a single circuit?
The current becomes too high.
Which statements must be true about the surface of a charged conductor in which no charge is moving?
The electric potential is constant over the surface.
The figure shows electrons passing through a resistor. The arrow shows the direction in which the electrons are moving. Which of the following statements are correct?
The electric potential is higher at point b than at point a.
A + 0.2 mC charge is in an electric field. What happens if that charge is replaced by a - 0.2 mC charge?
The electric potential stays the same, but the electric potential energy changes sign.
A +0.2 mC charge is in an electric field. What happens if that charge is replaced by a +0.4 mC charge?
The electric potential stays the same, but the electric potential energy doubles.
Fig. 16-50 shows electric field lines due to a point charge. What can you say about the field at point 1 compared with the field at point 2?
The field at point 1 is larger, because the field lines are closer together in that region.
A negative point charge is in an electric field created by a positive point charge. Which of the following is true?
The field points away from the positive charge, and the force on the negative charge is in the opposite direction to the field.
Two tiny beads are 25 cm apart with no other charges or fields present. Bead A carries 10 µC of charge and bead B carries 1 µC. Which one of the following statements is true about the magnitudes of the electric forces on these beads?
The force on A is exactly equal to the force on B.
A proton (Q = +e) and an electron (Q = -e) are in a constant electric field created by oppositely charged plates. You release the proton from near the positive plate and the electron from near the negative plate. Which feels the larger electric force?
The magnitude of the force is the same for both but in opposite directions.
A plastic rod and a glass rod are charged by rubbing with a piece of fur.
The plastic rod will be charged negatively
A region of space contains a uniform electric field, directed toward the right, as shown in the figure. Which statement about this situation is correct?
The potential at points A and B are equal, and the potential at point C is lower than the potential at point A.
When a battery is connected to a lightbulb properly, current flows through the lightbulb and makes it glow. How much current flows through the battery compared with the lightbulb?
The same amount.
A negatively-charged rod is brought close to (but does not touch) two neutral spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?
The sphere near the charged rod becomes positive and the other one becomes negative.
A solid aluminum cube rests on a wooden table in a region where a uniform external electric field is directed straight upward. What can we say concerning the charge on the top surface of the cube?
The top surface is charged positively.
Two protons are fired toward each other in a particle accelerator, with only the electrostatic force acting. Which of the following statements must be true about them as they move closer together?
Their electric potential energy keeps increasing
Two protons in close proximity are released from rest, with only the electrostatic force acting. Which of the following statements is not true about them as they move apart?
Their electric potential energy keeps increasing.
A proton and an electron are released from rest, with only the electrostatic force acting. Which of the following statements must be true about them as they move toward each other?
Their kinetic energy keeps increasing.
Nothing happens when birds land on a power line, yet we are warned not to touch a power line with a ladder. What is the difference?
There is little to no voltage drop between a bird's two feet, but there is a significant voltage drop between the top of a ladder touching a power line and the bottom of the ladder on the ground.
Fred the lightning bug has a mass m and a charge +q. Jane, his lightning-bug wife, has a mass of ¾m and a charge -2q. Because they have charges of opposite sign, they are attracted to each other. Which is attracted more to the other, and by how much?
They are attracted to each other by the same amount
An electron and a proton are released simultaneously from rest and start moving toward each other due to their electrostatic attraction, with no other forces present. Which of the following statements are true just before they are about to collide?
They are closer to the to the initial position of the proton that to the initial position of the electron.
The figure shows two unequal charges, +q and -Q. Charge -Q has greater magnitude than charge +q. Point X is midway between the charges. Within which section of the line will there be a point where the resultant electric field is zero?
VW
X and Y are two initially uncharged metal spheres on insulating stands, and they are in contact with each other.A positively charged rod R is brought close to X as shown in part (a) of the figure. Sphere Y is now moved away from X, as shown in part (b). What are the final charge states of X and Y?
X is negative and Y is positive.
If the result of your calculation of a quantity has SI units of kg⋅m/(s2⋅C), that quantity could be
an electric field strength.
If the result of your calculation of a quantity has SI units kg⋅m2/(s2⋅C), that quantity could be
an electric potential difference.
If the voltage across a circuit of constant resistance is doubled, the power dissipated by that circuit will
be four times as large.
If we double the resistance in a circuit but keep the current in it constant, the power dissipated by that circuit will
be two times as great.
As a proton moves in a direction perpendicular to the electric field lines
both its electric potential and electric potential energy remain constant.
When a current flows through an ionic liquid such as salty water, the moving charges are
both positive and negative ions.
If a quantity you calculated has units of A ∙ s, what is that quantity?
charge
For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?
current
For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?
current
If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit will
decrease to one-half its original value.
As an object acquires a positive charge, its mass usually
decreases.
The electric field at point P due to a point charge Q a distance R away from P has magnitude E. In order to double the magnitude of the field at P, you could
double the charge to 2Q
The electron⋅volt is a unit of
energy.
The unit of the kilowatt-hour is a measure of
energy.
If the electric potential at a point in space is zero, then the electric field at that point must be
impossible to determine based on the information given.
When the current through a ohmic device is increased by a factor of 4, the power dissipated by the ohmic device
increases by a factor of 16.
A hydrogen atom consists of a proton and an electron. If the orbital radius of the electron increases, the electric potential energy of the electron due to the proton
increases.
To be safe during a lightning storm, it is best to be
inside a metal car.
A plastic rod is charged up by rubbing a wool cloth, and brought to an initially neutral metallic sphere that is insulated from ground. It is allowed to touch the sphere for a few seconds, and then is separated from the sphere by a small distance. After the rod is separated, the rod
is repelled by the sphere.
As an electron is moved in the direction the electric field lines
it is moving from high potential to low potential and gaining electric potential energy.
As a proton moves in the direction the electric field lines
it is moving from high potential to low potential and losing electric potential energy.
We wish to determine the electric field E at a point near a positively charged metal sphere (a good conductor). We do so by bringing a small positive test charge, q0, to this point and measuring the force F0 on it. F0/q0 will be ___________ the electric field E as it was at that point before the test charge was present. greater than
less than
We are usually not aware of the electric force acting between two everyday objects because
most everyday objects have as many plus charges as minus charges.
A small metal ball hangs from the ceiling by an insulating thread. The ball is attracted to a positively charged rod held near the ball. The charge of the ball must be
negative or neutral.
When a current flows through a metal wire, the moving charges are
only electrons.
A negatively-charged plastic rod is brought close to (but does not touch) a neutral metal sphere that is connected to ground. After waiting a few seconds, the ground connection is removed (without touching the sphere), and after that the rod is also removed. The sphere is now
positively charged.
For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?
potential
If a quantity you calculated has units of , what is that quantity?
potential
Two stationary point charges q1 and q2 are shown in the figure along with a sketch of some field lines representing the electric field produced by them. What can you deduce from the sketch?
q1 is negative and q2 is positive; the magnitude of q1 is less than the magnitude of q2.
If the current flowing through a circuit of constant resistance is doubled, the power dissipated by that circuit will
quadruple in magnitude.
For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?
resistance
If a quantity you calculated has units of what is that quantity?
resistance
Two uncharged metal spheres, 1 and 2, are mounted on insulating support rods. A third metal sphere, carrying a positive charge, is then placed near 2. Now a copper wire is momentarily connected between 1 and 2 and then removed. Finally, sphere 3 is removed. In this final state
sphere 1 carries positive charge and 2 carries negative charge.
Two identical positive charges are placed near each other. At the point halfway between the two charges,
the electric field is zero and the potential is positive.
If two objects are electrically attracted to each other,
the objects could be electrically neutral.
The figure shows a graph of the power dissipated in a ohmic device as a function of the resistance. What quantity does the slope of this graph represent?
the square of the current in the ohmic device
A hydrogen nucleus, which has a charge +e, is situated to the left of a carbon nucleus, which has a charge +6e. The electrical force experienced by the hydrogen nucleus is
to the left, and the magnitude is equal to the force exerted on the carbon nucleus.
An electron is initially moving to the right when it enters a uniform electric field directed upwards, as shown in the figure. Which trajectory (X, Y, Z, or W) will the electron follow in the field?
trajectory Z
Four tiny charged particles (two having a charge +Q and two having a charge -Q) are distributed on the x- and y-axes as shown in the figure. Each charge is equidistant from the origin. In which direction is the net electric field at the point P on the y-axis?
upwards and a little towards the left
A proton is accelerated from rest through a potential difference V0 and gains a speed v0. If it were accelerated instead through a potential difference of 2V0, what speed would it gain?
v0st(2)
When connected to a battery, a lightbulb glows brightly. If the battery is reversed and reconnected to the bulb, the bulb will glow
with the same brightness.
Four charged particles (two having a charge +Q and two having a charge -Q) are arranged in the xy-plane as shown in the figure. The charges are all equidistant from the origin. The amount of work required to move a positively charged particle from point P to point O (both of which are on the z-axis) is
zero
Four charged particles (two having a charge +Q and two having a charge -Q) are arranged in the xy-plane, as shown in the figure. These particles are all equidistant from the origin. The electric potential (relative to infinity) at point P on the z-axis due to these particles, is
zero.