Physics II Exam III
The metal sphere in (Figure 1) hangs by a thread. When the north pole of a bar magnet is brought near, the sphere is strongly attracted to the magnet. Then the magnet is reversed and its south pole is brought near the sphere. How does the sphere respond? Explain. If an object is attracted to one pole of a magnet, it Blank the other pole. Therefore, the sphere would Blank
is attracted to, attract
Does the capacitance change? If so, by what factor? If not, why not? The capacitance Blank the separation of the plates of the parallel plate capacitor. That is, after the separation of the plates increases twice, the capacitance Blank.
is inversely proportional to, decreases by a factor of 2
(Figure 1) shows an electric field diagram. Dashed lines 11 and 22 are two surfaces in space, not physical objects. Is surface 11 an equipotential surface? What about surface 22? Explain why or why not. Equipotential surface Blank Therefore, Blank
is perpendicular to the field lines at every point, only surface 1 is equipotential
The figure shows three points in the vicinity of two point charges. The charges have equal magnitudes.(Figure 1) Rank in order, from most positive to most negative, the potentials VaVa to VcVc.
most positive vb> va=vc most negative
(31.7) In what direction is the electromagnetic wave traveling in the figure(Figure 1)a ?
out of the page
A red card is illuminated by red light. What color will the card appear?
red
After the charged rod has touched the wire and been removed, is the inner surface of the hollow sphere positive, negative, or not charged? Explain. A Gaussian surface through the conductor of the hollow sphere must contain a net _____ charge, so the inner surface of the larger conductor has to be _____ charged in order to provide the required net charge.
zero , negatively
What is the electric flux through surface CC in the figure? Give the answer as a multiple of qε0qε0.
0 (q/eo)
What is the electric flux through each of the surfaces in the figure(Figure 1)? Give each answer as a multiple of qϵ0qϵ0.
1, -1, 0 (q/eo)
(Figure 1) is the interference pattern seen on a viewing screen behind 2 slits. Suppose the 2 slits were replaced by 20 slits having the same spacing dd between adjacent slits. Would the width of each fringe increase, decrease, or stay the same?
The width of each fringe would decrease
The wire is broken on the right side of the circuit in (Figure 1). Suppose EE = 8 VV. What is the potential difference V1−V2V1−V2 between points 1 and 2? (28.3)
V1-V2 = 8V
Suppose that E⃗ =0⃗ V/mE→=0→V/m throughout some region of space. Can you conclude that V=0VV=0V in this region? Explain. Since the magnitude of E⃗ E→ equals to negative _____ ds,ds, we can conclude that VV _____ in this region.
derivative of V with respect to , equals some constant value
Suppose that V=0VV=0V throughout some region of space. Can you conclude that E⃗ =0⃗ V/mE→=0→V/m in this region? Explain. SSince VV is constant in some region of space and the magnitude of E⃗ E→ equals to negative _____ ds,ds, we can conclude that E⃗ E→ ___ in this region.
derivative of V with respect to , has zero magnitude
A fish in an aquarium with flat sides looks out at a hungry cat. To the fish, does the distance to the cat appear to be less than the actual distance, the same as the actual distance, or more than the actual distance? Explain. The distance to the cat appears to be Blank the actual distance because Blank.
greater than, the rays from the cat refract toward the normal
Does the potential difference ΔVCΔVC change as the separation increases? If so, by what factor? If not, why not? The potential difference of the capacitor is proportional to the electric field strength inside it and ___ the separation of its plates. That is, if the electric field strength remains constant and the separation increases twice, the potential difference ΔVCΔVC ____ .
is linearly proportional to , increases by a factor of 2
Select the correct direction of the field at point 2.
left
What will the surface charge density be if the radius of the disk is doubled but its total charge remains the same? Express your answer with the appropriate units.
n = 2.0 nC/cm^2
Three charges are placed at the corners of the triangle in (Figure 1). The ++++ charge has twice the quantity of charge of the two −− charges; the net charge is zero. Choose the correct equilibrium orientation
opposite charges in equal amounts
What is the difference between current and current density? Current is the Blank Current density is the current per Blank
rate at which charge moves through a wire, square meter of cross section of a wire
(29.9) Determine the magnetic field direction that causes the charged particle shown in the figure (b)(b) to experience the indicated magnetic force.
45∘ counterclockwise from straight down
What is the strength of the field at point 2 in (Figure 1).
E2 = 20 V/m
(Figure 1) is the interference pattern seen on a viewing screen behind 2 slits. Suppose the 2 slits were replaced by 20 slits having the same spacing dd between adjacent slits. Would the brightness of each fringe increase, decrease, or stay the same?
The brightness of each fringe would increase
The electric force on a charged particle in an electric field is F. What will be the force if the particle's charge is tripled and the electric field strength is halved?
(3F)/2
What is the strength of the field at point 1 in (Figure 1). (26.5)
E1 = 5 V/m
The two metal spheres in the figure(Figure 1) are connected by a metal wire with a switch in the middle. Initially the switch is open. Sphere 11, with the larger radius, is given a positive charge. Sphere 22, with the smaller radius, is neutral. Then the switch is closed. Afterward, sphere 11 has charge Q1Q1, is at potential V1V1, and the electric field strength at its surface is E1E1. The values for sphere 22 are Q2Q2, V2V2, and E2E2. Is Q1Q1 larger than, smaller than, or equal to Q2Q2?
Q1>Q2
Can an insulator be charged?
Yes
You see an upright, magnified image of your face when you look into a magnifying cosmetic mirror. Where is the image? Is it in front of the mirror's surface, on the mirror's surface, or behind the mirror's surface? Explain. The image is Blank the mirror's surface because it is formed by a Blank mirror with an object at a distance Blank the focal length.
behind, concave , nearer than
Is the object distance less than the focal length ff, between ff and 2ff, or greater than 2ff?
between f and 2f
A red card is illuminated by red light. What if it's illuminated by blue light?
black
(Figure 1) shows light waves passing through two closely spaced, narrow slits. The graph shows the intensity of light on a screen behind the slits. Select the correct graph showing how the light-intensity pattern will appear if the right slit is blocked. Assume the light is going through the left slit only.
generic almost curved line
Does the capacitor charge QQ change? If so, by what factor? If not, why not? The capacitor charge Blank its capacitance. Therefore, if the potential difference does not change and capacitance decreases twice, the charge QQ Blank.
is linearly proportional to, decreases by a factor of 2
Rank in order, from the potentials to most negative, the potentials VaVa to VcVc.(Figure 2)
most positive va> vb>vc> most negative
Initially bulbs AA and BB in (Figure 1) are glowing. What happens to each bulb if the switch is closed? Once the switch is closed, the current flows BlankbecauseBlank.
only through A , another bulb becomes short-circuited
A ___, which is an insulator or, can be charged by _______
plastic rod, rubbing it with wool
A battery supplies the energy to a circuit. Blank The battery Blank
true, supplies energy by creating a potential difference
(Figure 1) shows an electric field diagram. Dashed lines 11 and 22 are two surfaces in space, not physical objects. Rank in order the magnitudes of the potential differences ΔVabΔVab, ΔVcdΔVcd, and ΔVefΔVef. If we assume that the field strength is the same at all points, the magnitude of potential difference BlankTherefore, Blank
would be greatest between points with the greatest space along field lines, (delta(Vab))<(delta(Vcd))<(delta(Vef))
After the charged rod has touched the wire and been removed, is the outer surface of the hollow sphere positive, negative, or not charged? Explain. The hollow sphere initially had _____ net charge. Since the inner surface of the sphere has negative charge under given conditions, the outer surface has to be _____ charged in order to save the initial net charge.
zero, positively
Metal sphere A in (Figure 1) has 4 units of negative charge and identical metal sphere BB has 2 units of positive charge. The two spheres are brought into contact. What is the final charge state of sphere B?
)-1 (When the spheres brought into contact, the charges try to get an equilibrium distribution on both spheres. It means that same amount of positive charges neutralise the same amount of negative charges. Given that, metal sphere A has 4 units of negative charge and metal sphere B has 2 units of positive charge. So that, 2 units of negative charge will neutralize the 2 unit of positive charge of the second sphere. The others 2 units of negative charge of the first sphere will distribute equally on both spheres.)
(Figure 1) shows two points inside a capacitor. Let VV = 0 VV at the negative plate. What is the ratio E2/E1E2/E1 of the electric field strengths?
1
If you curl the fingers of your right hand as shown, are the electric fluxes in the figure(Figure 1)a positive or negative?
Negative
Suppose you have the uniformly charged cube in the figure(Figure 1). Can you use symmetry alone to deduce the shape of the cube's electric field? Can you use symmetry alone to deduce the shape of the cube's electric field?
No
(29.7) What is the initial direction of deflection for the charged particle entering the magnetic field shown in (Figure 1) (b)(b)?
No deflection
The figure(Figure 1)shows the viewing screen in a double-slit experiment. Fringe C is the central maximum. What will happen to the fringe spacing if the wavelength of the light is decreased?
The fringe spacing will decrease
The figure(Figure 1)shows the viewing screen in a double-slit experiment. Fringe C is the central maximum. What will happen to the fringe spacing if the distance to the screen is decreased?
The fringe spacing will decrease.
The figure(Figure 1)shows the viewing screen in a double-slit experiment. Fringe C is the central maximum. What will happen to the fringe spacing if the spacing between the slits is decreased?
The fringe spacing will increase
A small object is released in the center of the capacitor in the figure(Figure 1). For each situation, does the object move to the right, to the left, or remain in place? If it moves, does it accelerate or move at constant speed? A negative object is released from rest.
accelerates to the left
Is the electron's speed at f greater than, less than, or equal to its speed at i? Explain. The charges with the opposite signs __ each other. That is, the interaction force ___ the charges as they move farther apart. Therefore, the electron's speed at ff is ___ that at i.i.
attract to, tends to slow down, less than
(29.7) What is the initial direction of deflection for the charged particle entering the magnetic field shown in (Figure 1) (a)(a)?
into the page
Select the correct direction of the field at point 1.
left
A battery is a source of potential difference; the potential difference between the terminals of the battery is always the same. Blank A battery Blank The potential difference Blank
true, creates a potential difference by separating the positive and negative charges, is always the same for ideal batteries
What is the initial direction of deflection for the charged particle entering the magnetic field shown in (Figure 1) (a)(a)?
up
What is the electric flux through surface BB in the figure? Give the answer as a multiple of qε0qε0.
-4 (q/eo)
(Figure 1) is the interference pattern seen on a viewing screen behind 2 slits. Suppose the 2 slits were replaced by 20 slits having the same spacing dd between adjacent slits. Would the number of fringes on the screen increase, decrease, or stay the same?
The number of fringes would stay the same
Sharon drives her rocket through the magnetic field of (Figure 1) traveling to the right at a speed of 1000 m/sm/s as measured by Bill. As she passes Bill, she shoots a positive charge backward at a speed of 1000 m/sm/s relative to her.According to Sharon, what is the direction of the electric force?
Up
(34.2) You are looking at the image of a pencil in a mirror, as shown in figure 1 What happens to the image if the bottom half of the mirror is covered with a piece of cardboard?
You cannot see the pencil at all
(Figure 1) shows an electric field diagram. Dashed lines 11 and 22 are two surfaces in space, not physical objects. Is the electric potential at point aa higher than, lower than, or equal to the electric potential at point bb? Explain. The direction of the electric field lines Blank of electric potential. It means, that __________
coincides in the direction of decreasing, electric potential at a is higher than at b
The sphere and ellipsoid in (Figure 1) surround equal charges. Four students are discussing the situation. Student 1: The fluxes through AA and BB are equal because the average radius is the same. Student 2: I agree that the fluxes are equal, but that's because they enclose equal charges. Student 3: The electric field is not perpendicular to the surface for BB, and that makes the flux through BB less than the flux through AA. Student 4: I don't think that Gauss's law even applies to a situation like BB, so we can't compare the fluxes through AA and BB. According to the Gauss's law, the flux through the closed surface ______ the amount of the charge enclosed ______ the surface size or shape. Therefore, _____ is correct.
depends on, and does not depend on, student 2
An electron experiences a force of magnitude F when it is d = 1 cm from a very long, charged wire with linear charge density λ. If the charge density is doubled, at what distance from the wire will a proton experience a force of the same magnitude F? Explain. The electric field strength of the very long charged wire _______ the linear charge density of the wire and _____ as well as the force on the proton from that wire. Therefore, when the charge density is doubled, the proton would experience the same force magnitude if the distance between it and the wire is ______ .
is linearly proportional to, is inversely proportional to the distance between the wire and the proton, doubled
34.4 A light beam passing from medium 2 to medium 1 is refracted as shown in (Figure 1). Is n1n1 larger than n2n2, is n1n1 smaller than n2n2, or is there not enough information to tell? n1n1Blankn2n2 because Blank.
is smaller than, the angle of incidence is smaller than the angle of refraction
The circuit of (Figure 1) has two resistors, with R1>R2R1>R2.Which of the two resistors dissipates the larger amount of power? The power dissipated is Blank, since Blank, and the same current flows through each resistor.
larger for resistor R1 , P=I^2R
All the wires in (Figure 1) are made of the same material and have the same diameter. Rank in order, from largest to smallest, the currents Ia to Id.
largest Ia=Id>Ib=Ic
What is the initial direction of deflection for the charged particle entering the magnetic field shown in (Figure 1)(b)(b)?
left
Three charges are placed at the corners of the triangle in (Figure 1). The ++++ charge has twice the quantity of charge of the two −− charges; the net charge is zero. Is the triangle in equilibrium?
no
An electron moves along the trajectory of (Figure 1) from i to f. Does the electric potential energy increase, decrease, or stay the same? Explain. The electric potential energy of the charges is proportional to _____, so its absolute value ____ with increase of r. As the charges have opposite signs, the potential energy of the charges has ____ sign. Thus, the potential energy _____ as r increases.
r^-1, decreases, negative, increases
What is the current direction in the wire of (Figure 1)? The magnetic field produced by current is into the page on the left of the wire and it is out of the page on the right of the wire. That is, to determine the direction of the current you need to grab the wire with your Blankof the wire. Since the thumb now points Blank
right hand in such a way that your fingers point out of the page to the right, down the current in the wire is downward
A lightweight metal ball hangs by a thread. When a charged rod is held near, the ball moves toward the rod, touches the rod, then quickly "flies away" from the rod. When the ball touches the rod, ______. Objects become _____ and , therefore, repel each other.
some charge is transferred between the rod and the ball, equally charged
(34.2) You are looking at the image of a pencil in a mirror, as shown in figure 1 You see the whole pencil in part A and you cannot see the pencil in part B. Why? Light is scattered off all points of the pencil and into all directions of space. Before reaching the eye, the scattered light rays Blank. Due to the given position of the pencil, the mirror, and the eye, light scattered from each point of the pencil can reach the eye only by reflecting from the Blank half of the mirror, so this half must be open in order for the eye to see the reflection.
strike the mirror at an acute angle and reflect into the eye at the same angle, bottom
The parallel-plate capacitor in (Figure 1) is connected to a battery having potential difference ΔVbatΔVbat. Without breaking any of the connections, insulating handles are used to increase the plate separation to 2d2d. Does the potential difference ΔVCΔVC change as the separation increases? If so, by what factor? If not, why not? Since the capacitor stays connected to the battery, Blank. Therefore, after the separation of the plates increases twice, ΔVCΔVC Blank.
the potential difference across the capacitor stays the same, does not change
Does bulb AA get brighter, stay the same, or get dimmer? Blank, therefore, bulb A Blank.
the voltage across it becomes larger, gets brighter
The two metal spheres in the figure(Figure 1) are connected by a metal wire with a switch in the middle. Initially the switch is open. Sphere 11, with the larger radius, is given a positive charge. Sphere 22, with the smaller radius, is neutral. Then the switch is closed. Afterward, sphere 11 has charge Q1Q1, is at potential V1V1, and the electric field strength at its surface is E1E1. The values for sphere 22 are Q2Q2, V2V2, and E2E2. Is V1V1 larger than, smaller than, or equal to V2V2?
v1=v2
A small object is released in the center of the capacitor in the figure(Figure 1). For each situation, does the object move to the right, to the left, or remain in place? If it moves, does it accelerate or move at constant speed? A positive object is released from rest _______
accelerates to the right
Does the electric field strength EE change as the separation increases? If so, by what factor? If not, why not? The electric field strength EE of a parallel plate capacitor ___ the separation of its plates. That is, EE __ .
does not depend on, does not change
A small, metal sphere hangs by an insulating thread within the larger, hollow conducting sphere of (Figure 1). A conducting wire extends from the small sphere through, but not touching, a small hole in the hollow sphere. A charged rod is used to transfer positive charge to the protruding wire. After the charged rod has touched the wire and been removed, is the small sphere positive, negative, or not charged? Explain. Positive charge has been transferred to the wire, which is connected to the small sphere. Since the small sphere ____ electrostatic equilibrium with the wire, the sphere has _____ charge.
is in , a positive
Bulbs AA and BB in (Figure 1) are identical, and both are glowing. Bulb BB is removed from its socket.Does the potential difference ΔV12ΔV12 between points 11 and 22 increase, stay the same, decrease, or become zero? Before bulb B is removed from its socket the voltage across it Blank. Once bulb B is removed Blank. That is, the potential difference between points 1 and 2 Blank
is less than emf of the battery because there is a non-zero voltage across the resistor in the right branch, the current and voltage across the right resistor become zero, so delta V12 becomes equal to the emf battery
A capacitor with plates separated by distance dd is charged to a potential difference ΔVCΔVC. All wires and batteries are disconnected, then the two plates are pulled apart (with insulated handles) to a new separation of distance 2d2d. Does the capacitor charge QQ change as the separation increases? If so, by what factor? If not, why not? If all wires and batteries are disconnected from capacitor, the charge __ into or out of it. The total charge in this case __ the separation of the plates. Therefore, the charge QQ__ .
is noy able to flow, does not depend on, does not change
A small object is released in the center of the capacitor in the figure(Figure 1). For each situation, does the object move to the right, to the left, or remain in place? If it moves, does it accelerate or move at constant speed? A neutral but polarizable object is released from rest.
remains in place
Is (Figure 1) a possible surface charge distribution for a current-carrying wire? If so, in which direction is the current? If not, why not? The distribution of surface charges along a wire creates a net electric field inside the wire. To produce a constant current this field __________ . The field due to the charge distribution given ____________ in the wire in the figure.
should have constant direction, varies its direction so there cannot be a constant current
(31.7) In what direction is the electromagnetic wave traveling in the figure (Figure 2)b?
upward
Metal sphere A in (Figure 1) has 4 units of negative charge and identical metal sphere BB has 2 units of positive charge. The two spheres are brought into contact. What is the final charge state of sphere A?
)-1 (When the spheres brought into contact, the charges try to get an equilibrium distribution on both spheres. It means that same amount of positive charges neutralise the same amount of negative charges. Given that, metal sphere A has 4 units of negative charge and metal sphere B has 2 units of positive charge. So that, 2 units of negative charge will neutralize the 2 unit of positive charge of the second sphere. The others 2 units of negative charge of the first sphere will distribute equally on both spheres.)
What is the electric flux through surface EE in the figure? Give the answer as a multiple of qε0qε0.
0 (q/eo)
The figure(Figure 1)shows the viewing screen in a double-slit experiment. Fringe C is the central maximum. Suppose the wavelength of the light is 490 nmnm . How much farther is it from the dot on the screen in the center of fringe E to the left slit than it is from the dot to the right slit?
980 nm
Sharon drives her rocket through the magnetic field of (Figure 1) traveling to the right at a speed of 1000 m/sm/s as measured by Bill. As she passes Bill, she shoots a positive charge backward at a speed of 1000 m/sm/s relative to her. According to Sharon, what kind of force or forces act on the charge?
Both magnetic and electric forces
Sharon drives her rocket through the magnetic field of (Figure 1) traveling to the right at a speed of 1000 m/sm/s as measured by Bill. As she passes Bill, she shoots a positive charge backward at a speed of 1000 m/sm/s relative to her. According to Sharon, what is the direction of the magnetic force?
Down
The two metal spheres in the figure(Figure 1) are connected by a metal wire with a switch in the middle. Initially the switch is open. Sphere 11, with the larger radius, is given a positive charge. Sphere 22, with the smaller radius, is neutral. Then the switch is closed. Afterward, sphere 11 has charge Q1Q1, is at potential V1V1, and the electric field strength at its surface is E1E1. The values for sphere 22 are Q2Q2, V2V2, and E2E2. Is E1E1 larger than, smaller than, or equal to E2E2?
E1<E2
A battery is a source of current; the current leaving the battery is always the same. Blank Actually, Blank. The current Blank
False, whether the current flow through a battery or not depends on the other elements of the circuit, its not always the same since it depends on the resistance in the circuit
The intensity of an electromagnetic wave is 40 W/m2W/m2. What will the intensity be if the amplitude of the electric field is doubled?
I = 160 W/m^2
The intensity of an electromagnetic wave is 40 W/m2W/m2. What will the intensity be if the amplitude of the magnetic field is doubled?
I = 160 W/m^2
The intensity of an electromagnetic wave is 40 W/m2W/m2. What will the intensity be if the amplitudes of both the electric and the magnetic fields are doubled?
I = 160 W/m^2
The intensity of an electromagnetic wave is 40 W/m2W/m2. What will the intensity be if the frequency is doubled?
I = 40 W/m^2
Sharon drives her rocket through the magnetic field of (Figure 1) traveling to the right at a speed of 1000 m/sm/s as measured by Bill. As she passes Bill, she shoots a positive charge backward at a speed of 1000 m/sm/s relative to her. According to Bill, what kind of force or forces act on the charge?
No forces
(34.2) You are looking at the image of a pencil in a mirror, as shown in figure 1 What happens to the image if the top half of the mirror, down to the midpoint, is covered with a piece of cardboard?
Nothing happens to the image.
Part B If you curl the fingers of your right hand as shown, are the electric fluxes in the figure (Figure 2)b positive or negative? Suppose that you curl the fingers along the side of the loop shown at the right in this perspective.
Positive
(Figure 1) is the interference pattern seen on a viewing screen behind 2 slits. Suppose the 2 slits were replaced by 20 slits having the same spacing dd between adjacent slits. Would the fringe spacing increase, decrease, or stay the same?
The fringe spacing would stay the same
Determine the position (or positions) in (Figure 1) where an electron would experience no net force. If there is more than one answer, enter them in ascending order separated by comma(s). If there is no answer, enter 0.
10
Charge q1 is distance rr from a positive point charge Q. Charge q2=q1/3q2=q1/3 is distance 2r from Q. What is the ratio U1/U2 of their potential energies due to their interactions with Q?U1/U2 =
6
(Figure 1) shows two points inside a capacitor. Let VV = 0 VV at the negative plate. What is the ratio V2/V1V2/V1 of the electric potentials?
3
What is the electric flux through surface DD in the figure? Give the answer as a multiple of qε0qε0.
3 (q/eo)
What is the electric flux through surface AA in the figure(Figure 1)? Give the answer as a multiple of qε0qε0. (24.6)
4.00(q/eo)
(29.9) Determine the magnetic field direction that causes the charged particle shown in the figure(Figure 1) (a)(a) to experience the indicated magnetic force.
45∘ clockwise from straight up
Charge q1 is distance ss from the negative plate of a parallel-plate capacitor. Charge q2=q1/3q2=q1/3 is distance 2s from the negative plate. What is the ratio U1/U2 of their potential energies?
1.5
