Physics MC

*Diagram with 2 hanging spheres* Two identical, uncharged, nonconducting spheres hang vertically from insulating strings and are a distance of 10cm apart, as shown in the figure above. The spheres are then each given a net charge; sphere A gets -10uC and sphere B gets -20uC. The spheres are allowed to come to rest in new equilibrium configuration. *1.25.* Let y=0 be the vertical position of the uncharged spheres, with positive y toward the top of the page. Which of the following correctly ranks the new vertical positions y sub A and y sub B of spheres A and B, respectively, in the new equilibrium configuration?

(y sub A = y sub B) > 0

*Diagram with a proton moving downward of a wire with current traveling left to right* *2.11.* A proton with a velocity v is moving directly away from a wire carrying a current I directed to the right in the +x direction as shown in the figure. The proton will experience a force in which direction?

+x

*1.36.* An object is placed in front of a thin lens. An upright image is formed that is one-third the height of the object. If the image is 6.0 cm from the lens, what is the focal length of the lens?

-9 cm

*Diagram with a particle inserted through a hole in the the right side of a plate (+V) and into a field created by that plate and a parallel plate (-V) to the left of the first plate* *2.27.* An electron of charge -e and mass m is launched with a velocity of v sub 0 through a small hole in the right plate of a parallel plate capacitor toward the opposite plate a distance d away. The electric potential of both plates are equal in magnitude, but opposite +-V as shown in the figure. What is the kinetic energy of the electron as it reaches the left plate?

1/2mv sub 0 + 2 Ve

*1.6.* *Graph with P on the Y-axis & V on the X-axis* An ideal gas is initially in state 1 at a temperature of 200K. The gas is taken through the two reversible thermodynamic processes shown in the PV diagram above. The process from state 1 to state 2 is isothermal. The process from state 2 to state 3 is isobaric. What is the temperature of the gas when it is in state 3?

400 K

*Table with top row Volume (cm^3), middle row Pressure (kPa), and bottom row Temperature (Degrees Celsius)* *2.46.* A technician is experimenting with a sample of gas in a closed container and produces this set of data. What can be concluded from this data? *(Select two answers.)*

Pressure is directly proportional to the temperature. *&* The number of molecules of gas in the container is 4.4 x 10^-4 moles.

*1.17.* *Diagram with electroscope & charged rod* An initially uncharged electroscope consists of two thin, 50 cm long conducting wires attached to a cap, with a 25 g conducting sphere attached to the other end of the wire. When a charged rod is brought close to but not touching the cap, as shown above, the spheres separate a distance of 30 cm. What can be determined about the induced charge on each sphere from this information?

The magnitude but not the sign.

*1.18.* *Diagram with 3 piped reservoirs with equal amounts of water* Three identical reservoirs, B, and C, are represented above, each with a small pipe where water exits horizontally, The pipes are set at the same height above a pool of water. The water in the reservoirs is kept at the levels shown. Which of the following correctly ranks the horizontal distances d that the streams of water travel before hitting the surface of the pool?

d sub C > d sub B > d sub A

*Lightbulb Diagram* *2.50.* An incandescent bulb is shown in the figure. When the connected to the same power source, which of the following would make this lightbulb brighter? *(Select two answers.)*

increase the thickness of the filament *&* connect two of the existing filaments in parallel

*1.19.* *Diagram with 5 energy levels labeled 0 eV, -0.5 eV, -1.0 eV, -5.0 eV, and -10 eV from top to bottom* A hypothetical hydrogen-like atom has energy states as represented in the energy-level diagram above. The atom is in the ground state when it absorbs a photon with frequency 2.18 x 10^15 Hz. What energy state will the atom be in after it absorbs the photon?

n = 3

*2.3.* At which location is the electric field strongest, and which direction is the electric field?

*Arrow pointing south*

*1.5.* *Graph with Current (A) on Y-axis & Potential Difference (V) on X-axis* The above graph shows current as a function of potential difference for two different filament lamps. If the two lamps are connected in parallel to a 3.0 V battery, what is the total current supplied by the battery?

1.6 A

*Diagram with a hose connected to a lawn sprinkler* *2.20.* A 2-cm diameter hose leads up to a lawn sprinkler with ten 2-mm exit holes as shown in the figure. The velocity of the water in the hose is v sub 1. What is the velocity of the water exiting the holes?

10 v sub 1

*1.4.* X Y Z -4q +q -q ->-------->---------> -a 0 a The figure above shows three objects (X, Y, and Z) that have charges -4q, +q, and -q, respectively. The objects are held fixed on an axis at the positions shown. The magnitude of the electrostatic force exerted by object Y on object Z is F. What is the magnitude of the net electrostatic force exerted on object Y due to the other two objects?

3F

*1.30.* The Sun's energy production is due to the fusion of ^1H into ^4He. How does the mass of four ^1H nuclei (4m sub H) compare with the mass of one ^4He nucleus (m sub He)?

4m sub H > m sub He

*Diagram with a circuit containing 3 resistors, 2 ammeters, a battery, a capacitor and a switch* *2.28.* The circuit shown in the figure consists of three identical resistors, two ammeters, a battery, a capacitor, and a switch. The capacitor is initially unchanged and the switch is open. What happens to the readings of the ammeters immediately after the switch is closed?

A sub 1: decrease A sub 2: increase

*Diagram with an electric potential field* *2.25.* In a region of space, there is an electric potential field with isolines as shown in the figure. Which of the following is the most accurate description of the electric field in the region?

An electric field is directed to the left with a uniform strength of 75 V/m.

*1.31.* *Graph with Number of Molecules on the Y-axis & Speed on the X-axis. The parabola labeled "Initial" is a high-peaking, steep parabola and the parabola labeled "Final" is a low-peaking, shallow parabola* The graph above shows the initial and final molecular speed distributions of a gas as a result of a thermodynamic process. Which of the following processes could produce this change?

Compression of the gas with no transfer of energy by heating

*1.2.* A small amount of charge is placed on both an isolated conducting sphere and an isolated insulating sphere. For both spheres, the charge is added at a small area at the top of the sphere. After a few seconds, where on each of the spheres is the charge that was added?

Conducting: Spread over the Surface Insulating: At the top

*2.17.* A very slow-moving positron interacts with a stationary electron. Which of the following statements correctly describes a possible outcome of this reaction and why would it occur?

Conservation of momentum indicates that two identical rays moving off in opposite directions could be created.

*Diagram with 2 parallel plates separated by the distance x serving as a capacitor connected to a battery* *2.10.* A capacitor with movable parallel plates is connected to a battery. The plates of the capacitor are originally a distance x apart as shown in the figure. With the battery still connected, what happens to the energy stored in the capacitor and the electric field between the capacitor plates, if the plates are moved to a new distance x/2?

Energy: increases Electric Field: increases

*2.45.* In an experiment, monochromatic violet light shines on a photosensitive metal, which causes electrons to be ejected from the metal. Which of the following graphs best depicts the number of ejected electrons and the maximum energy of the ejected electrons versus the intensity of the violet light shining on the metal?

First graph: positive sloping line Second graph: horizontal line

*Diagram with 3 resistors of different sizes* *2.8.* Which of the following correctly ranks the current in the resistors?

I sub X = I sub Y = I sub Z

*Diagram with 2 charges separated by distance D* *2.5.* Two charges are separated by a distance D as shown in the figure. Charge #1, on the left, has a mass of M and a charge of -2Q. Charge #2, on the right, has a mass of 2M and a charge of +Q. The two charges are released. Where will the charges collide and why?

The charges will collide closer to charge #2 because the center of mass is closer to charge #2 and there are no other forces on the system.

*1.14.* *Circuit with 3 resistors, a capacitor and a battery* A 25 (ohm) resistor and a 100 (ohm) resistor are connected in a circuit with a third resistor of unknown resistance R, a capacitor of unknown capacitance C, and a battery of unknown emf (emf), as shown above. After a long time, the potential difference across the 25 (ohm) resistor is measured to be 4 V. What is the emf of the battery?

The emf of the battery cannot be determined without knowing the value of R.

*2.22.* Two identical containers are filled with different gases. Container 1 is filled with hydrogen and container 2 is filled with nitrogen. Each container is set on a lab table and allowed to come to thermal equilibrium with the room. Which of the following correctly compares the properties of the two gases?

The pressures of the gases cannot be compared without knowing the number of molecules in each container.

*Graph of the wave function of a particle* *2.19.* The figure shows the wave function of particle moving along along the x-axis. Which of the following statements correctly interprets the graph?

There is an equal probability of finding the particle at 1.5 nm as at 4.5 nm.

*1.9.* *Circuit diagram* The figure above shows a circuit containing four resistors, a battery, and two ammeters. The current in ammeter A sub 1 is 1.0 A, and the current in ammeter A sub 2 is 0.6 A. The two resistors labeled R are identical. What are the currents in R sub 2 and in each of the two resistors labeled R?

R sub 2: 0.4 A Each R: 0.3 A

*Diagram with a battery, 2 ammeters, 3 resistors and a switch* *2.6.* The circuit shown has a battery of emf E; three identical resistors, R; two ammeters A sub 1 and A sub 2; and a switch that is initially in the open position as shown in the figure. When the switch is closed, what happens to the current reading in the two ammeters?

A sub 1: increases A sub 2: decreases

*2.47.* In which of the following cases would it be appropriate to ignore the gravitational force? *(Select two answers.)*

A teacher charges a balloon with her hair and demonstrates how the balloon can be stuck to the ceiling by the electrostatic force. *&* Electrons move through a wire in an electrical circuit.

*Diagram with a Doll, Lens and Screen (from left to right); a card is lowered down to the left go the Lens* *2.43.* A lens is placed between a doll and a white sheet of paper in such a way as to produce an image on the paper. On the side of the lens facing the doll, a dark card is slowly lowered to cover the lens as shown in the figure. Which of the following correctly explains what will happen to the image of the doll?

As the card blocks light from the object, the image remains clear but becomes increasingly dim until the image disappears.

*Diagram with location A, B, and C separated by +4q and -q* *2.26.* Which of the following correctly represents the relationship between the electric field strengths at locations A, B, and C?

E sub B > E sub A > E sub C *This is an easy one to remember... cuz Cook couldn't f***'n explain it*

You and a friend are traveling in a car. You tune the car radio to a station of 850 kHz. The graph below represents the electric field strength of the radio wave at a given position as a function of time. *Sin graph with Electric Field (x 10^-4 V/m) on the Y-axis & Time (us) on the X-axis* *1.13.* Which of the following best represents the electric field strength E measured in V/m as a function of time t measured in us?

E=(1.5x10^-4)sin(5.32t)

*Diagram with a circuit containing a lot of shit* *2.49.* The circuit shown has a battery of negligible internal resistance, resistors, and a switch. There are voltmeters, which measure the potential differences V sub 1, and V sub 2, and ammeters A sub 1, A sub 2, A sub 3, which measure the currents I sub 1, I sub 2, and I sub 3. The switch is initially in the closed position. With the switch still closed, which of the following relationships are true? *(Select two answers.)*

I sub 1 + I sub 2 - I sub 3 = 0 *&* */_\*V sub B - V sub 1 - V sub 2 = 0

*Diagram with figures interacting with a charged rod* *2.48.* An electroscope is shown with its movable metal leaves in a sequence of events. Originally the electroscope is in a position with the leaves at an outward angle as shown in Figure 1. A negatively charged rod is brought close to the electroscope and the leaves swing downward as shown in Figure 2. Finally, the rod touches the electroscope and the leaves spring outward as shown in Figure 3. Which of the following statements correctly describe this behavior? *(Select two answers.)*

In Figure 1, the electroscope has a net positive charge. *&* In Figure 2, negative charges are pushed toward the leaves at the bottom of the electroscope.

*Diagram with object moving parallel to a wire* *1.133.* An object with charge q is initially moving at a constant speed v parallel to a wire carrying current I, as shown in the figure above. The object is at a distance d from the wire, and the magnetic force exerted on the object by the wire is F. Which of the following changes, when made individually, will result in a magnetic force of 2F? Select two answers.

Increasing the current to 2I *&* Decreasing the distance to 0.5d

*1.32.* *Diagram with an electron moving to the right towards a grey square; the Point P is located to the right of the bottom right corner of the square* An electron is moving to the right, as shown in the figure above. It passes through the shaded region, which contains a magnetic field. The electron travels along a path that takes it through point P. the gravitational force on the electron is negligible. What is the direction of the magnetic field?

Into the page

*1.22.* A student is given a loudspeaker with a square opening and asked to make a change in the dimensions of the opening so that the sound wave is more spread out vertically and narrowed horizontally. Which of the following is the correct use of the principle of diffraction to accomplish the desired result?

Make the opening into a rectangle with a longer horizontal dimension and a shorter vertical dimension.

*Diagram with 2 hanging spheres* Two identical, uncharged, nonconducting spheres hang vertically from insulating strings and are a distance of 10cm apart, as shown in the figure above. The spheres are then each given a net charge; sphere A gets -10uC and sphere B gets -20uC. The spheres are allowed to come to rest in new equilibrium configuration. *1.28.* Consider a position P located halfway between the charged spheres in their new equilibrium configuration. Which of the following correctly indicates whether the electric potential at this position is positive, negative, or zero and explains why?

Negative, because both negatively charged spheres contribute to negative electric potential to the total.

*1.1.* An insulated container with a divider in the middle contains two separated gases. Gas 1 is initially at a higher temperature than gas 2. The divider is then removed. Which of the following observations might be made over a period of time as the two gases mix together, and why?

On average, the molecules of gas 1 lose some of their kinetic energy to the molecules of gas 2 through collisions, resulting in the two gases eventually having the same temperature.

*Diagram with an electron placed in an electric field flowing to the right and an electron placed in a separate magnetic field flowing to the right* *2.14.* An electron e is placed in an electric field and a second electron is placed in a magnetic field as shown in the figure. Both are released from rest at the same time. How do the forces on the charges compare?

One electron experiences a constant force, while the other experiences no force.

*1.34.* An ideal gas with molecules of mass m is contained in a cube with sides of area A. The pressure exerted by the gas on the top of the cube is P, and N molecules hit the top of the cube in a time /_\(change in)t. What is the average vertical component of the velocity of the gas molecules?

PA/_\t/2Nm

*Diagram with 5 particles being injected into a space created by 2 parallel plates* *2.1.* A beam of various particles is launched into the space between two oppositely charged parallel plates as shown in the figure. It is known that the particles are all traveling at the same initial velocity as they enter the region, and the particle P is a proton. What else can be inferred?

Particle A could be a B-particle.

*1.29.* *Diagram with negatively charged sphere, followed by a rod, followed by another rod (from left to right)* Two electrically neutral conducting rods are near a negatively charged sphere, as shown in the figure above. Rod 1 is touched to rod 2 for several seconds, and then the rods are separated. The rods are then both removed from the vicinity of the charged sphere. Which of the following best describes the resulting net charge on each rod?

Rod 1 is positively charged, and rod 2 is negatively charged.

You and a friend are traveling in a car. You tune the car radio to a station of 850 kHz. The graph below represents the electric field strength of the radio wave at a given position as a function of time. *Sin graph with Electric Field (x 10^-4 V/m) on the Y-axis & Time (us) on the X-axis* *1.12.* Both the sound and radio waves are present inside the car. Which of the following is true about these waves?

Sound waves require a medium in which to propagate and radio waves do not.

*1.8.* A ray of light in air (n=1.0) is incident on glass (n=1.5) at a small angle *theta subscript a* to the normal. The angle of the ray to the normal in the glass is *theta subscript g*. The speeds of light in air and the glass are *v subscript a* and *v subscript g* respectively. How do the values of the speed of light and the angle of the ray of light to the normal in air compare to those in the glass?

Speed of Light: *v sub a* > *v sub g* Angle to Normal: *theta sub a* > *theta sub g*

*Diagram of PV containing 2 points and 2 different routes from one point to the other* *2.41.* A sample of gas can be taken from an initial pressure P sub 0 and volume V sub 0 to a final pressure and volume along either path 1 or 2 as shown in the figure. Your lab partner states: "Moving along either path won't make any difference because both paths start and end at the same places. So, everything everything about the gases during both processes 1 and 2 will be the same." Which of the following is a proper analysis of your lab partner's statement?

The change in internal energies will be the same, but the thermal energy transferred to the gas will be different.

*1.134.* A simple generator contains a conducting loop that rotates between the poles of a magnet. Which of the following helps explain why this rotation generates a potential difference? Select two answers.

The component of the magnetic field perpendicular to the loop changes. *&* The angle between the plane of the loop and the magnetic field changes.

*Diagram with a weight on top of a floating piece of styrofoam that is submerged in water* *2.38.* A mass is fixed to the top a Styrofoam block that floats in a container of water. The mass is large enough to make the water line flush with the top of the Styrofoam as shown in the figure. What will happen if the Styrofoam is inverted so that the mass is now suspended under the block?

The contraption floats with the waterline below the top of the Styrofoam.

*1.21.* Which of the following correctly describes the motion of particles when a single transverse mechanical wave passes through a medium?

The particles vibrate back and forth along a single direction that is perpendicular to the direction of propagation of the wave.

*1.16.* A typical iron nucleus contains 30 neutrons and 26 protons, Which of the following explains why the nucleus stays together despite the electric repulsion between the protons?

The net strong force on each proton due to all the nucleons is stronger than the net repulsive force.

*Diagram with some stuff* *2.37.* A photon of wavelength (lambda) collides with a stationary electron glancing off at an angle of (theta), while the electron moves off with an angle measured from the the original path of the photon as shown in the figure. Which of the following statements correctly states the effect on the wavelength of the scattered photon and why?

The wavelength of the scattered photon increases because the photon transfers energy to the electron in the interaction.

*Diagram with 3 resistors of different sizes* *2.9.* Which of the following correctly ranks the potential difference across the resistors?

V sub Z > V sub X > V sub Y

*2.40.* A person can stand outside on a cold (HOLY S%#! does this even exist?!?!) day for hours without ill effect, but falling into a cold lake can kill a person in a matter of minutes. Which of the following is the primary reason for this phenomenon?

Water has more more molecules per volume than air, increasing molecular contact with the person.

*Diagram with 4 lines illustrating an electric potential field with 3 charges; The figure shows an electric potential field created by charges that are not shown* *2.2.* A small negative charge is placed at the location labeled A. Which one of the following vectors most closely depicts the direction of the electric force on the charge?

*Arrow pointing northwest*

*2.36.* A scientist is using an electron microscope to study the structure of viruses ranging in size from 20 to 300 nm. The scientist must adjust the accelerating potential of the microscope to create an electron of the proper speed and wavelength to produce a detailed image of the virus. Which of the following graphs best depicts the relationship between accelerating voltage and the wavelength of the electrons?

*Graph with curve decreasing and concave up*

*Graph of a parabola with Number of Molecules on the Y-axis & Speed on the X-axis* *2.23.* The graph shows the distribution of speeds from a gas sample at temperature T. The gas is heated to a higher temperature. Which of the following depicts a possible distribution after the gas has been heated? (Horizontal line N and vertical line S are shown for reference.)

*Just memorize the f***ing graph of answer choice D, guys*

*1.20.* In each of the following nuclear reactions given below, a product is indicated by the letter X. In which of the reactions does the letter X represent a positron? (A positron is a positively charged particle with the same mass and magnitude of charge as a electron.)

15 8 O --> 15 7 N + X + v

*2.18.* 14 6 C decays into 14 7 N and an electron. The half-life of Carbon-14 is 5730 years. Which of the following statements is correct?

Carbon-14 has the same number of protons as carbon-11.

*2.30.* An electronics manufacturer needs a 1.2 (ohm) resistor for a phone it is designing. The company has calculated that it is less expensive to build the 1.2 (ohm) resistor from the cheaper 1 (ohm) and 2 (ohm) resistors than to purchase the 1.2 (ohm) resistor from a supplier. Which of the following resistor arrangements is equivalent to 1.2 (ohm) and is the most effective method to construct the 1.2 (ohm) resistor?

*Circuit with a 1 (ohm) resistor in series with a 2 (ohm) resistor; both of those resistors are in parallel with a 2 (ohm) resistor*

*1.24.* A student in an electronics lab is studying the electrical properties of pieces of graphite. The student applies a potential difference of 24 V across the length of a cylindrical piece of graphite with a radius of 0.7 mm. The student wants the same current in both pieces of graphite. What potential difference should the student apply across the 0.7 mm piece?

12 V

*1.35.* *Diagram with a magnetic field going into the page and a proton moving to the right toward the field* A proton is moving at 4.4x10^5 m/s in the plane of the page when it enters a magnetic field of magnitude 0.04 T perpendicular to the page, a shown in the figure above. The radius of curvature of the path of the proton as it moves through the magnetic field is approximately which of the following?

1x10^-1 m

*1.11.* *Graph with Pressure on the Y-axis & Volume on the X-axis. Within the graph lies Point X, segments 1&2, and curve 3* The graph above shows pressure as a function of volume for a sample of an ideal gas. The gas has an internal energy of 1000 J at state X and is taken through the cycle shown. Process 3 is isothermal. The work that the gas does on the environment is 400 J during process 1 and 250 J during one complete cycle. What is the net thermal energy transferred into the gas during one complete cycle?

250 J

*1.7.* *Diagram with 2 metal bars running parallel to each other with perpendicular tanks on each end* Two metal bars with the same length and same cross-sectional area are placed between two tanks with temperatures of 400 K and 300 K, as shown above. The thermal conductivity of the top bar is 200 W/m*K, and that of the bottom bar is 400 W/m*K. If the net energy transferred through the top bar in a given time interval is Q, what is the net energy transferred through the bottom bar during the same time interval?

2Q

*1.10.* *Graph with Potential Difference (V) on the Y-axis & Current (A) on the X-axis* The graph above shows experimental data for the potential difference across a lightbulb as a function of the current through the lightbulb. The power dissipated by the lightbulb when the potential difference across the bulb is 12 V is most nearly

9.6 W

*Diagram with large bar magnet A (north pointed right) next to small bar magnet (north pointed left)* *2.33.* A child playing with two magnets places them close together and holds them in place to keep them from moving, as shown in the figure. Magnet A has a larger magnetic field and a larger mass than magnet B. What will happen when the magnets are released and free to move?

Magnet A will accelerate away more slowly than magnet B because magnet A has a larger mass.

*Diagram with 2 hanging spheres* Two identical, uncharged, nonconducting spheres hang vertically from insulating strings and are a distance of 10cm apart, as shown in the figure above. The spheres are then each given a net charge; sphere A gets -10uC and sphere B gets -20uC. The spheres are allowed to come to rest in new equilibrium configuration. *1.26.* Let E sub A be the magnitude of the electric field produced by sphere A near the location of sphere B, and let E sub B be the magnitude of the electric field produced by sphere B near the location of sphere A. Which of the following correctly ranks E sub A and E sub B and provides a correct justification for the rankings?

E sub A < E sub B, because at the same distance away from a point charge, a larger-magnitude charge will produce a larger-magnitude electric field, and sphere B has twice as much charge on it.

*1.23.* *Diagram with a candle and a lens separated by distance d and the same lens and a screen separated by distance s (from left to right)* In the experimental setup shown in the figure above, a thin lens stands between a candle and a screen. A student moves the candle to several positions relative to the lens and then adjusts the position of the screen until an image is formed. Each time, the student records the distance d from the candle to the lens and the distance s from the lens to the screen. Which of the following procedures will allow the student to determine the focal length of the lens?

Graph 1/s as a function of 1/d. The focal length will be the inverse of the vertical intercept.

*1.15.* *Diagram with particle traveling in between a positive plate parallel to a negative plate* A positively charged particle is moving horizontally when it enters the uniform electric field between two parallel charged plates, as shown in the figure above. Which of the following could show the x and y positions of the particle as a function of time t?

Graph: Y-axis labeled "x"; positive sloping line. Graph: Y-axis labelend "y"; concave down, negative sloping curve.

*Diagram with a charge or -5uC placed next to a bar magnet with the north end pointed left* *2.13.* A stationary charge is placed a small distance from an iron bar magnet as shown in the figure. Which of the following correctly indicates the cause and direction of the force on the charge?

The charge experiences an electric force to the right.

*Graph with 2 points; Pressure on the Y-axis & Volume on the X-axis* *2.24.* The graph shows the pressure and volume of a gas being taken from state #1 to state #2, in a very quick process, where there is not enough time for heat to either leave or enter the gas. Which of the following correctly indicates the sign of the work done on the gas, and the change in temperature of the gas?

Work Done: - */_\* Temperature: +

*1.33.* Water flowing in a horizontal pipe speeds up as it goes from a section with a large diameter to a section with a small diameter. Which of the following can explain why the speed of the water increases?

Work is done because the water in the larger pipe has a higher pressure.

*1.131.* Which of the following phenomena involving light can be explained with a particle model? Select two answers.

The photoelectric effect *&* Atomic Emission

*Diagram with 2 hanging spheres* Two identical, uncharged, nonconducting spheres hang vertically from insulating strings and are a distance of 10cm apart, as shown in the figure above. The spheres are then each given a net charge; sphere A gets -10uC and sphere B gets -20uC. The spheres are allowed to come to rest in new equilibrium configuration. *1.27.* Consider a system defined as only spheres A and B. In the new equilibrium configuration, how (if at all) has the potential energy of the system changed compared to when the spheres were initially uncharged, and why?

The potential energy of the system has increased, because the two spheres repel each other, storing energy in an electric field.

*Table with Number of Resistors Connected to the Battery in the left column & Power Delivered to the Resistors (W) in the right column* *2.29.* A student connects a single resistor to a 10-V battery and takes measurements to find the power delivered by the battery to the resistor. The student then adds another resistor to the circuit and measures the power delivered to both resistors. This process is repeated, adding one resistor at a time, until the battery is connected to five resistors. The data from the experiment is given. Which is the following can be conducted from the data?

The resistors are all identical and are connected in series.

*Diagram with a laser pointer directed at a screen and through a piece of hair* *2.15.* A technician sets up a red laser pointer and directs light at a strand of hair suspended between two blocks in such a way that the light falls on a screen behind the hair as shown in the figure. This produces a pattern of alternating light and dark fringes on the screen. The technician makes on change to the setup and repeats the procedure. This change produces a similar pattern, but the light and dark fringes are spaced farther apart. Which of the following could account for this different pattern?

The screen was moved farther away from the hair.

*Diagram of differently sized beakers X, Y, and Z* *2.39.* Three beakers of different sizes are filled with water as shown. Each beaker has a rubber stopper of the identical size and shape fitted to a drain hole in the side. Which correctly ranks the force applied to the stoppers by the water?

X = Y = X

*Diagram with circuit including a switch, 2 resistors and a battery* *1.132* A battery of unknown internal resistance r is placed in a circuit with a switch S and a resistor of known resistance R = 10 (ohms), as shown in the figure above. The internal resistance r can be determined by taking measurements with the switch open and with the switch closed. Which of the following pairs of measurements with the switch open and closed can be used to determine the value of r? Select two answers.

With Switch Open: Potential difference between X and Z With Switch Closed: Current at Y *&* With Switch Open: Potential difference between X and Z With Switch Closed: Potential difference between Y and Z

*Diagram with a container containing 3 differently shaped tubes* *2.21.* Oil is very slowly poured into the container shown in the figure until the fluid enters the three open tube X, Y, and Z. The oil does not overflow any of the tubes. Which of the following correctly ranks the height of the oil in each of the three tubes?

X = Y = Z

*Diagram with a light beam passing through a prism and exiting at 3 different spots* *2.16.* Your lab group has been asked to determine the index of refraction of a plastic rectangular prism. Your partner places the prism on a sheet of paper, traces its shape, shines a beam of light through the prism, and traces the incoming ray. The light exits the prism at multiple locations. Your partner marks the exit locations of the three brightest rays on the side of the prism as shown in the figure. Is this enough information to determine the index of refraction of the prism and why?

Yes, by measuring ray angles with a protractor and using the concepts of refraction

*Scatterplot with Current (A) on the Y-axis & Voltage (V) on the X-axis* *2.7.* A kitchen toaster is connected to a variable power supply. The voltage difference across and current through the toaster are measured for various settings of the power supply. The figure shows the graph of the data. The resistance of the toaster:

is constant at 5.0 (ohms)

*2.42.* A glass lens lens of focal length f = 80 cm in air is submerged in oil. How will submerging the lens in oil affect the focal length of the lens and why?

f>80 cm because there is now a smaller change in velocity as light passes from oil into glass.

*Diagram with a sphere charged +Q and a sphere charged -Q separated by distance d; a sphere charged +q approaches the midpoint of the other 2 spheres from the right* *2.4.* Two spheres with charges +Q and -Q of equal magnitude are placed a vertical distance d apart on the y-axis as shown in the figure. A third charge +q is brought from a distance x, where x>>d, horizontally toward the midpoint between +Q and -Q. The net force on +q as it is moved to the left along the x-axis:

increases and remains in the same direction

*Diagram with Particle P moving upward into a magnetic field that is between 2 plates and directed into the page* *2.12.* A magnetic field directed into the page in the -z direction is placed between the plates of a charged capacitor as shown in the figure. The magnetic and electric fields are adjusted so that a particle of charge +1 e moving at a velocity of v will pass straight through the fields in the +y direction. Which of the following changes will cause the particle to deflect to the left as it passes through the fields?

increasing the velocity v of the particle

*12 6 C + 1 1 H --> 13 7 N + ÿ* *2.44.* Which of the following expressions correctly relates the masses of the constituent particles involved in the nuclear reaction shown?

m sub C + m sub H - m sub N - (hf/c^2) = 0

*2.32.* Under which of the following conditions would it be appropriate to neglect the gravitational force on a a charge in a magnetic field?

mg<<qvB

*Diagram with... too much happening* *2.31.* Which of the following shown in the figure will cause current flow in the wire loop?

moving a magnet from above a loop of wire to the right as indicated with arrow B

*Diagram with a bar magnet (north pointed up) under particle +Q* *2.34.* A charge +Q is positioned close to a bar magnet as shown in the figure. If the charge is experiencing a force into the page, which way must the charge be moving?

to the left

*Graph with 1/d sub o the Y-axis & 1/d sub i on the X-axis* *2.35.* You were absent when your AP Physics 2 class performed a lens lab. When you return to school, the teacher says to get the data from a friend and complete the assignment of calculating the focal length of the lens used in the lab. Your friend hands you the graph shown in the figure where d sub o and d sub i are the object and image distances. Which of the following is equal to the focal length of the lens?

the inverse of the y-intercept of the best-fit line