AP Physics Final
Two conducting plates hold equal and opposite charges that create an electric field of magnitude E = 95N/C that is directed to the right, as shown in the figure above. Points A and B are 0.75 cm apart with A closer to the positive plate. A proton is released from rest at point A. What is the kinetic energy of the proton when it reaches point B?
+1.14×10^−19 J
A hollow conducting sphere is surrounded by a larger concentric spherical conducting shell, as shown above. The inner sphere has a net charge of -Q, and the outer sphere has a net charge of +3Q. What is the net charge on the outer surface of the spherical shell?
+2Q
A hollow conducting sphere is surrounded by a larger concentric spherical conducting shell, as shown above. The inner sphere has a net charge of -Q, and the outer sphere has a net charge of +3Q. What is the net charge on the inner surface of the spherical shell?
+Q
Two concentric spherical conducting shells and four labeled points are shown above. The outer shell has a net charge Q=−20nC. The inner shell has a net charge q=+10nC. What is the charge on the outer surface of the outer shell?
-10 nC
Points A and B shown above are in the plane of the page and 55 meters apart. The points are located in a uniform electric field of magnitude 1000V/m directed toward the bottom of the page. When a proton (of charge +e ) moves from point A to point B, how much work is done on the proton by the electric field?
-3000 eV
The figure above shows two charged spherical conductors, X and Y, which are equal in size. When each conductor is isolated and surrounded by a closed cubical surface, the total electric flux through the surfaces is +Φ0 for conductor X and − Φ40 for conductor Y. Conductor Y is brought into contact with conductor X and then separated. If the separation is small so that both conductors are inside the same closed cubical surface, as shown above, what is the total electric flux through the surface?
-3Φ0
After the switch is closed in the circuit above, the current in the circuit is given by i=I(1−e−t/τ) , where I and τ are constants. What is the value of I?
0.001 A
An inductor with inductance L = 0.30 H is connected in series with a resistor and both are connected to a power supply, as shown above. The power supply generates a current I that is given as a function of time t by the equation I = I0 (1-t/k), where I0 = 4.0 A and k = 2.0 s . What is the magnitude of the potential difference across the inductor induced by the changing current?
0.60 V
An uncharged 3.0 μF capacitor is placed in a circuit with an ideal battery, two resistors, and an open switch S, as shown in the figure above. The switch is then closed. What is the current in the 20 Ω resistor a long time after the switch is closed?
1.0 A
The y-component of the magnetic field B is given as a function of time t by the equation By = -α + βt, where α = 4.0 T and β = 3.0 T/s. A coil of wire with an area of 2.0 m2 and a resistance of 6.0 Ω is placed in this field, parallel to the xz-plane at y= 2.0 cm. The current in the coil at time t = 1.2 s is most nearly
1.0 A
An inductor and two resistors are connected to an ideal battery, as shown in the figure above. What is the time constant for the circuit?
1.0 μs
A small sphere has a charge +q. Spherical Gaussian surfaces A and B are concentric with the sphere, as shown in the figure above. The radii of surfaces A and B are r and 2r, respectively. The magnitude of the electric flux through A is ΦA The magnitude of the electric flux through surface B is ΦB . The ratio ΦA/ΦB is
1/1
The circuit shown above has three capacitors and a 12V battery. The capacitors are charged to steady state conditions. One of the capacitors is removed from the circuit and isolated. While it still holds all of its charge, a piece of ceramic with dielectric constant of 2 is inserted and completely fills the space between the plates. Ui is the energy stored in the capacitor before the dielectric was inserted, and Uf is the energy stored in the capacitor after the dielectric was inserted. What is the ratio Uf/Ui?
1/2
A parallel plate capacitor is connected across a voltage V so that each plate of the capacitor collects a charge of magnitude Q. Which of the following is an expression for the energy stored in the capacitor?
1/2 QV
The magnetic field at a perpendicular distance r from a long, straight current-carrying wire is directly proportional to
1/r
After the switch is closed in the circuit above, the current in the circuit is given by i=I(1−e−t/τ) , where I and τ are constants. What is the value of τ?
2.5 ×10^-4 s
A copper wire of length L and diameter D dissipates energy at a rate P0 when the current in the wire is 10A. A second copper wire of length L has diameter 2D. What current in the second wire would dissipate energy at a rate P0?
20A
Two resistors of resistances R and 12 Ω are connected to a battery of emf 18V, as shown in the figure above. The battery has an internal resistance of r. The current in the battery is 1.5A, and the current in the 12 Ω resistor is 1.0 A. What is the resistance R?
24 Ω
Time t is the time it takes the current of an LR circuit with an inductor of inductance L and a resistor of resistance R to reach half of its maximum value. What is the new time if the original inductor is replaced with an inductor of inductance 2L ?
2t
Two wires perpendicular to the x-axis have currents I directed out of the page, as shown above. Each wire is a distance d from the y-axis. Point P lies on the y-axis at the coordinate (0,a), and point R lies on the x-axis at the coordinate (−d/2,0). Which of the following expressions represents the magnitude of the magnetic field at point R?
2u0I/3pid
An uncharged 3.0 μF capacitor is placed in a circuit with an ideal battery, two resistors, and an open switch S, as shown in the figure above. The switch is then closed. What is the current in the 10 Ω resistor immediately after the switch is closed?
3.0 A
Two positive point charges, both of magnitude 4.0×10−6C, are situated along the x-axis at x1=−2.0m and x2=+2.0m. What is the electric potential at the origin of the xy-coordinate system?
3.6×10^4 V
Six 2 Ω resistors are connected to a 12 V battery, as shown in the figure above. What is the current in the resistor labeled R ?
3.7 A
Three identical capacitors with capacitance C are arranged as shown above. What is the equivalent capacitance between points A and B?
3C/2
A capacitor of capacitance Ca is first charged to a voltage V0, as shown above on the left. Without losing any charge, the capacitor is now disconnected from the voltage source and connected to a second initially uncharged capacitor of capacitance Cb that is three times Ca, and the circuit is allowed to reach equilibrium, as shown above on the right. If Qa is the new charge on capacitor Ca, the charge Qb on capacitor Cb is given by
3Qa
Two resistors of resistances R and 12 Ω are connected to a battery of emf 18V, as shown in the figure above. The battery has an internal resistance of r. The current in the battery is 1.5A, and the current in the 12 Ω resistor is 1.0 A. What is the internal resistance of the battery?
4.0 Ω
A small sphere has a charge +q. Spherical Gaussian surfaces A and B are concentric with the sphere, as shown in the figure above. The radii of surfaces A and B are r and 2r, respectively. The magnitude of the electric field at surface A is EA. The magnitude of the electric field at surface B is EB. The ratio EA / EB is
4/1
A conducting rod of resistance R is in electrical contact with a frictionless U-shaped rail of width L and negligible resistance. The rod is pulled to the right at a constant velocity v. A magnetic field B is directed into the page, as shown in the figure above. Under these conditions, the electric power dissipated in the rod is P. If the velocity of the rod is doubled, the power dissipated in the rod is
4P
Capacitors C1 and C2 are connected as shown in the circuit above. The capacitance of C1 is C, and the capacitance of C2 is C/3 . The equivalent capacitance between points A and B is CEQ. A dielectric is inserted into capacitor C2 , and the equivalent capacitance between points A and B is now 2CEQ . What is the value of the dielectric constant for this dielectric?
5
In the circuit shown, R1 = 6Ω , R2 = 3Ω, and the emf ε of the battery is 30 V. The reading of the ammeter A is most nearly
5.0 A
The circuit shown above has three capacitors and a 12V battery. The capacitors are charged to steady state conditions. What is the potential difference across capacitor C1?
8.0 V
The capacitor in the circuit represented above is uncharged when the switch is at position B. The switch is then moved to position A. What is the energy stored by the capacitor when the current in the circuit is 2.0 mA?
8.0 mJ
Three small spheres, A, B, and C, have charges with magnitudes qA, qB, and qC, respectively.The three spheres are aligned along a straight line, as shown in the figure above. At the instant shown, the net force on sphere A is zero. The ratio qC/qB is
9/4
Two small spheres are arranged along a line and carry charges of +4Q and -3Q, as shown in the figure above. The vertical lines are equally spaced. At which of the labeled points does the electric potential have the largest positive value?
A
A bar magnet with its south pole pointing down is released from rest and falls through a wire coil, as shown above. A resistor is connected across the two ends of the coil. What current would be produced in the coil, as observed by a person directly above the coil?
A current that is first clockwise and then counterclockwise
A loop of wire lies in the plane of the page in a region with a uniform magnetic field B directed into the page, as shown in the figure above. In which of the following cases, if any, will an emf be induced in the loop at the moment shown in the figure?
An emf cannot be induced in the loop without changing its orientation relative to the magnetic field.
Three identical spheres are equally spaced from one another. Spheres 1 and 2 have charge +Q, and sphere 3 has a charge of -Q, as shown in the figure above. Five different positions are labeled A, B, C, D, and E. Positions A, B, and C are all the same distance from sphere 3. Positions C, D, and E are all the same distance from sphere 2. All spheres and points lie in the same plane. At which of the five positions are the horizontal and vertical components of the electric field directed toward the left and the top of the page, respectively?
B
A circuit contains three identical light bulbs and a switch S connected to an ideal battery of emf ε, as shown in the figure above. The switch is initially open and bulbs A and B have equal brightness, while C is not lit. What happens to the brightness of bulbs A and B when the switch S is closed and bulb C lights up?
Bulb A becomes brighter Bulb B becomes dimmer
Two small spheres are arranged along a line and carry charges of +4Q and -3Q, as shown in the figure above. The vertical lines are equally spaced. At which of the labeled points does the electric field point toward the right with the smallest magnitude?
C
Four parallel plate capacitors all have the same plate area and have the plate separations shown above. Both capacitors A and B have air between the plates, while the space between the plates of both capacitors C and D is filled with a dielectric slab of dielectric constant κ=2. Which of the following correctly ranks the capacitors in order of their capacitance from largest to smallest?
C>(A=D)>B
A parallel plate capacitor with air between the plates is charged and then disconnected from the source of emf. If the space between the plates is now filled with a dielectric, what happens to the capacitance of the capacitor and the magnitude of the electric field between the plates?
Capacitance increases magnitude of the electric field decreases
A parallel-plate capacitor connected to an ideal battery has charge +Q on its top plate. The energy stored in the capacitor is Uc. While the capacitor remains connected to the battery, the separation between the two plates is doubled. Which of the following gives the new charge on the top plate and the new energy stored in the capacitor?
Charge: +Q/2 Potential Energy: Uc/2
Three small spheres, A, B, and C, have charges with magnitudes qA, qB, and qC, respectively.The three spheres are aligned along a straight line, as shown in the figure above. At the instant shown, the net force on sphere A is zero. Which of the following statements must be true of the signs of the charges?
Charges qB and qC have different signs.
Three identical spheres are equally spaced from one another. Spheres 1 and 2 have charge +Q, and sphere 3 has a charge of -Q, as shown in the figure above. Five different positions are labeled A, B, C, D, and E. Positions A, B, and C are all the same distance from sphere 3. Positions C, D, and E are all the same distance from sphere 2. All spheres and points lie in the same plane. The electric potential is highest at position
D
A semicircular loop with a clockwise current is placed in a uniform magnetic field that is directed into the page, as shown in the figure above. F1−→ is the net force on segment 1, the straight portion of the loop. F2−→ is the net force on segment 2, the curved portion of the loop. Which of the following correctly indicates the directions and relative magnitudes of the forces F1−→ and F2−→
Direction of F1 toward the bottom of the page Direction of F2 toward the top of the page magnitudes f1 = f2
The figure above shows a thin, square, nonconducting sheet of positive charge uniformly distributed over its area. The length of each side of the sheet is a. Point C is at the center of the sheet. Point X is a distance d above the center of the sheet, and point Y is a distance 2d above the center of the sheet. Assume a >> d. The effect of gravity is negligible. If the magnitude of the electric field at point X is E, what is the magnitude of the electric field at point Y?
E
Two concentric spherical conducting shells and four labeled points are shown above. The outer shell has a net charge Q=−20nC. The inner shell has a net charge q=+10nC. The magnitudes of the electric fields at the four labeled points in the figure are ER, ES, ET, and EU, respectively. Which of the following correctly ranks the points according to the magnitude of their electric fields?
ES>ET>(ER=EU)
A variable voltage source is connected to an inductor of inductance L. The voltage V as a function of time t is given by the equation V(t) = βt2 , where β is a constant in units of V/s2. The current in the inductor at time t = 0 is zero. Which of the following equations gives the magnitude of the current in the inductor as a function of time?
I (t) = B/3L (t^3)
Which of the following will increase the magnetic field on the axis of a long solenoid? I. Increasing the current in the solenoid II. Increasing the cross-sectional area of the solenoid III. Inserting an iron core into the solenoid
I and III only
A beam of particles travels at a right angle to a uniform magnetic field. Particles can be separated into different trajectories based on which of the following properties? I. The charge of the particle II. The mass of the particle III. The velocity of the particle
I, II, and III
Which of the following could be true for a Gaussian surface through which the net flux is zero? I. There are no charges inside the surface. II. The net charge enclosed by the surface is zero. III. The electric field is zero everywhere on the surface.
I, II, and III
An electron is traveling with speed v when it enters a uniform magnetic field that is directed into the page, as shown above. Five paths in the magnetic field are labeled A, B, C, D, and E. The electron is replaced with a proton that is traveling at the same speed v� in the same direction as it enters the magnetic field. Which of the following best describes the motion of the proton as it passes through the magnetic field? I. The speed of the proton changes less than the speed of the electron did. II. The proton is deflected in the opposite direction. III. The proton is deflected more than the electron.
II only
Which of the following must be true for a Gaussian surface through which the net flux is zero? I. There are no charges inside the surface. II. The net charge enclosed by the surface is zero. III. The electric field is zero everywhere on the surface.
II only
An electron is placed near a wire carrying current I, as shown in the figure above, and released from rest. Both the electron and the wire are in the plane of the page. Which of the following is true about the direction of the initial magnetic force acting on the electron due to the current in the wire?
It has no direction because the magnitude of the initial magnetic force on the electron is zero.
The figure above shows a cross section of a solid, isolated, metallic conductor in electrostatic equilibrium with a net charge +Q. The two ends of the conductor are spherical surfaces of radii rX and rY, where rX<rY . Points X and Y are on the conductor at each end. Assuming that the electric potential is zero an infinite distance from the conductor, which of the following statements is true about the magnitude of the electric potential at points X and Y?
It has the same nonzero value at both points X and Y.
The figure above shows a cross section of a solid, isolated, metallic conductor in electrostatic equilibrium with a net charge +Q. The two ends of the conductor are spherical surfaces of radii rX and rY, where rX<rY . Points X and Y are on the conductor at each end. Which of the following is true about the magnitude of the electric field just outside the surface of the conductor at points X and Y?
It is greater at point X than at point Y.
Three small spheres, A, B, and C, have charges with magnitudes qA, qB, and qC, respectively.The three spheres are aligned along a straight line, as shown in the figure above. At the instant shown, the net force on sphere A is zero. Which of the following is true about the sign of charge qA?
It is possible that qA could be either positive or negative.
The figure above shows two charged spherical conductors, X and Y, which are equal in size. When each conductor is isolated and surrounded by a closed cubical surface, the total electric flux through the surfaces is +Φ0 for conductor X and − Φ40 for conductor Y. Conductor Y is then moved closer to conductor X until it is just outside a closed cubical surface containing conductor X, as shown in the figure above. How would the total electric flux through the cubical surface change as conductor Y is moving?
It would remain constant, but the flux through each side of the cubical surface would change.
Three long wires, R, S, and T, are in the positions and carrying the currents indicated in the figure above. All currents are in the plane of the page and in the direction indicated. What are the magnitude and direction of the magnetic field at the origin?
Magnitude 2u0I/pi direction into the page
Two long, straight parallel wires X and Y are separated by a distance d and carry currents I and 2I, as shown in the figure above. The force on wire X has magnitude F. If the current in each wire is both doubled and reversed in direction, which of the following is true of the magnitude and direction of the new force on wire X?
Magnitude 4F Direction unchanged
Two concentric circular wire loops carry equal currents I in opposite directions, as shown in the figure above. The inner loop has a radius a and carries a counterclockwise current. The outer loop has a radius b and carries a clockwise current. What is the magnitude and direction of the magnetic field at the center of the loops?
Magnitude u0I/2 (1/a - 1/b) Direction out of the page
Object A and object B are separated by distance d. Object A has charge +q, and object B has charge -2q. Object A has a force of magnitude F exerted on it by object B. What are the magnitude and direction of the force exerted on object B?
Magnitude: F Direction: Towards object A
An electric dipole consisting of a positive charge and a negative charge held a fixed distance apart is at rest in an external, nonuniform electric field E, as shown in the figure above. Which of the following best describes the net torque and net force exerted on the dipole?
Net torque clockwise Net force to the right
A grounded spherical conductor is on an insulating stand. A positively charged rod is brought close to the sphere but does not touch the sphere, as shown above. The rod is moved far away and then the grounding wire is removed. Which of the following describes the resulting charge on the sphere?
No net charge and no polarization
A copper rod of resistance R is in electrical contact with a frictionless U-shaped rail of width L and negligible resistance. The rod is pulled to the right at a constant velocity v. A magnetic field B is directed into the page, as shown in the figure above. Under these conditions, the electric power dissipated in the rod is P. If the velocity of the rod is doubled and the magnetic field strength is reduced by half, the power dissipated in the rod is
P
An electron is traveling with speed v when it enters a uniform magnetic field that is directed into the page, as shown above. Five paths in the magnetic field are labeled A, B, C, D, and E. Which labeled path best shows the path the electron will follow as it travels through the magnetic field?
Path D
A parallel-plate capacitor connected to a battery is fully charged with the switch S closed, as shown in the circuit above. A slab of dielectric constant K > 1 is slowly inserted between the plates of the capacitor. If, instead, the switch is open with the capacitor still fully charged when the slab is inserted, what changes, if any, occur?
Potential difference across the plates decreases Charge on positive plate remains the same
A parallel-plate capacitor connected to a battery is fully charged with the switch S closed, as shown in the circuit above. A slab of dielectric constant K > 1 is slowly inserted between the plates of the capacitor. If the switch remains closed when the slab is inserted, what changes, if any, occur?
Potential difference across the plates remains the same Charge on positive plate increases
When a battery is connected to an external resistance R, as shown above on the left, there is a current I in the circuit. When the external resistance is changed to 3R, the current changes to I/2, as shown above on the right. What is the internal resistance r of the battery?
R
Three resistors are connected to an ideal battery, as shown in the figure above. The battery has an emf ε . Two of the resistors have known resistances R and 2R. The third resistor has unknown resistance X. The current in two of the branches is shown. What is the value of the unknown resistance X ?
R/2
A positively charged particle travels along the path shown in the figure above through region 1 and between two parallel plates in region 2. A magnetic field exists in region 1, and one of the plates in region 2 is at a higher potential than the other. What is the direction of the magnetic field in region 1, and which plate is at a higher potential in region 2 ?
Region 1 out of the page plate at higher potential top plate
Conducting spheres A and B of charges −q and +3q, respectively, are separated by a distance d, as shown in the figure above. Which of the following statements is true about the two spheres?
The force sphere B exerts on sphere A is equal in magnitude to the force sphere A exerts on sphere B.
A parallel plate capacitor is connected to a battery, fully charged, disconnected, and isolated from the battery. A dielectric slab is then inserted between the plates of the capacitor. Which of the following is a true statement about what happens when the dielectric slab is inserted?
The potential difference between the plates of the capacitor will decrease.
A resistor of resistance R is connected in a circuit to two identical batteries. The circuit also contains switch S and ideal voltmeter V, as shown in the figure above. The batteries both have an emf ε and internal resistance r. The reading of the voltmeter is noted with the switch in the open position. Which of the following best represents how the voltmeter reading after the switch is closed compares to the reading before the switch is closed?
The reading of the voltmeter is lower
Three long, current-carrying wires are shown in the cross-sectional view above. The currents in wires R and S are out of the page, and the current in wire T is into the page. The currents in the wires have equal magnitude, and the wires are in the positions shown. Point P is halfway between wires S and T. To which of the following locations, if any, could wire S be moved so that the total magnetic force exerted on it by the other two wires is zero?
There is no position in the vicinity of the wires at which the magnetic force on wire S would be zero.
Two stationary point charges of unknown magnitude and sign are isolated from all other charges. If the electric field strength is zero at the midpoint of the line joining them, which of the following can be concluded about the charges?
They are equal in magnitude and have the same sign.
Four isolated arrangements of charged spheres are created for an experiment, as shown above. Which of the following correctly compares the electric potential energy U of the arrangements? Assume U=0 when the charges are an infinite distance apart.
UA>UB>UD>UC
In the figure above, two small spheres, each with charge +Q, are fixed in place at the corners of an equilateral triangle. Point I is at the third corner, and point II is midway between the charges. Which of the following best describes the relationship between the electric potentials VI and VII at points I and II, respectively?
VI<VII
A capacitor of capacitance Ca is first charged to a voltage V0, as shown above on the left. Without losing any charge, the capacitor is now disconnected from the voltage source and connected to a second initially uncharged capacitor of capacitance Cb that is three times Ca, and the circuit is allowed to reach equilibrium, as shown above on the right. The new voltage across capacitor Ca is Va. How does this new voltage compare with the original voltage of V0?
Va<V0
Three capacitors are connected in series to an ideal voltage source and charged, as shown in Figure 1 above. The capacitors are identical except that capacitor X has air between its plates, whereas capacitors Y and Z each have a dielectric slab of dielectric constant κ > 1 between their plates. If the dielectric slab is removed from capacitor Z, as shown in Figure 2, which of the following describes what will happen to the voltage across each capacitor?
Voltage across Capacitor X decreases Voltage across Capacitor Y decreases Voltage across Capacitor Z increases
In the figure above, two small spheres, each with charge +Q, are fixed in place at the corners of an equilateral triangle. Point I is at the third corner, and point II is midway between the charges. A small particle with charge +q, where q << Q, is moved from point I to point II at constant speed v by an external force. WEXT is the work done by the external force on the moving charge, and WELEC is the work done by the electrostatic force. Which of the following correctly identifies the signs of these quantities?
Wext is positive Welec is negative
Two small spheres have charges +Q and -Q and are located at the bottom corners of an equilateral triangle, as shown in the figure above. The equilateral triangle has sides of length a, and point P is at the top corner of the triangle. The electric potential at point P due to the two spheres is
Zero (0)
Two wires perpendicular to the x-axis have currents I directed out of the page, as shown above. Each wire is a distance d from the y-axis. Point P lies on the y-axis at the coordinate (0,a), and point R lies on the x-axis at the coordinate (−d/2,0). Which of the following best represents the direction of the net magnetic field at point P?
arrow pointing to the left
A circuit is constructed using a battery of emf ε, a resistor of resistance R, a capacitor of capacitance C, an inductor of inductance L, and three switches, as shown in the figure above. The three switches are labeled S1 , S2 , and S3 , and they can be operated independently. All switches are open, and there is no stored energy in the capacitor or the inductor. Switch S3 is closed. What is the current in the inductor after steady state has been reached?
emf/R
The advantage of using a dielectric in a capacitor is that it
increases the capacitance of the capacitor
An electron is placed near a wire carrying current I, as shown in the figure above, and released from rest. Both the electron and the wire are in the plane of the page. Which of the following is true about the direction of the magnetic field produced by the current at the position of the electron?
it is into the page
A metal wire of resistance 10 Ω is bent into a circular hoop of radius 0.10 meter and placed in a uniform magnetic field, as shown in Figure 1 above. The magnetic field strength B as a function of time is shown in Figure 2, where positive refers to a magnetic field directed out of the page. What are the magnitude and direction of the current induced in the ring at time t = 6 s?
magnitude 0.42 mA Direction: counterclockwise
Three long, current-carrying wires are shown in the cross-sectional view above. The currents in wires R and S are out of the page, and the current in wire T is into the page. The currents in the wires have equal magnitude, and the wires are in the positions shown. Point P is halfway between wires S and T. If Bs is the magnitude of the magnetic field at point P due to wire S, which of the following gives the magnitude and direction of the magnetic field at point P due to all three wires?
magnitude 5bs/2 direction top of the page
A positively charged particle moves in the positive x-direction in a uniform magnetic field directed in the positive y-direction. The net force on the particle could be zero if there is also an electric field present in the
negative z direction
A negatively charged ion is moving toward the top of the page when it enters a region of space with a uniform magnetic field B directed to the right, as shown above. The direction of the force that the magnetic field exerts on the ion is
out of the page
The figure above shows a thin, square, nonconducting sheet of positive charge uniformly distributed over its area. The length of each side of the sheet is a. Point C is at the center of the sheet. Point X is a distance d above the center of the sheet, and point Y is a distance 2d above the center of the sheet. Assume a >> d. The effect of gravity is negligible. A positive point charge +q is released from rest at point X. If the magnitude of the electric field at point X is E, what is the kinetic energy of the charge at point Y?
qEd
Two small spheres have charges +Q and -Q and are located at the bottom corners of an equilateral triangle, as shown in the figure above. The equilateral triangle has sides of length a, and point P is at the top corner of the triangle. The direction of the electric field at point P due to the two spheres is
to the right
Three long wires perpendicular to the page are equidistant from each other, as shown in the cross-sectional view above. Two wires carry current into the page, and the third carries current out of the page. All the currents are equal in magnitude. What is the direction of the net magnetic force on wire A due to the other two wires?
toward the right
A circuit is constructed using a battery of emf ε, a resistor of resistance R, a capacitor of capacitance C, an inductor of inductance L, and three switches, as shown in the figure above. The three switches are labeled S1 , S2 , and S3 , and they can be operated independently. All switches are open, and there is no stored energy in the capacitor or the inductor. Switch S1 is closed. After the capacitor is fully charged, switch S1 is opened and switch S2 is closed. Which of the following expressions represents the maximum current in the LC circuit?
ε√C/L
The figure above shows two charged spherical conductors, X and Y, which are equal in size. When each conductor is isolated and surrounded by a closed cubical surface, the total electric flux through the surfaces is +Φ0 for conductor X and − Φ40 for conductor Y. After being brought into contact with conductor X, conductor Y is moved a very large distance away from conductor X. What is the total electric flux through a closed cubical surface surrounding conductor X, as shown above?
−3/2Φ0
Two small spheres have charges +Q and -Q and are located at the bottom corners of an equilateral triangle, as shown in the figure above. The equilateral triangle has sides of length a, and point P is at the top corner of the triangle. The potential energy stored in the charge configuration shown is
−Q^2/4πε0a
