Physics Final Review Conceptual Questions

Four magnetic moments are shown in a uniform magnetic field. B is moving directly toward positive x. All magnetic moments have the same angle with B. 1 is moving diagonally left and upward 2 is moving diagonally right and upward 3 is moving diagonally right and downward 4 is moving diagonally left and downward Which moments feel the largest potential energy?

(1) and (4)

Several resistors are connected in series. Which of the following statements is correct? Choose all that are correct. (1) The equivalent resistance is greater than any of the resistances in the group (2) The equivalent resistance is less than any of the resistances in the group (3) The equivalent resistance depends on the voltage applied across the group (4) The equivalent resistance is equal to the sum of the resistances in thr group (5) None of those statements are correct

(1) and (4)

A proton moving horizontally enters a region where a uniform magnetic field is directed perpendicular to the proton's velocity. After the proton enters the field, it... (1) is deflected downward with constant speed (2) is deflected upward moving in a semicircular path with constant speed and exits the field moving left (3) continues to move in the horizontal direction with constant velocity (4) movies in a circular orbit and becomes trapped by the field

(2)

If three unequal capacitors, initially uncharged, are connected in series across a battery, which of the following statements is true? (1) The equivalent capacitance is greater than any of the individual capacitances (2) The largest voltage appears across the small capacitance (3) The largest voltage appears across the largest capacitance (4) The capacitor with the largest capacitance has the greatest charge (5) The capacitor with the smallest capacitance has the smallest charge

(2)

When resistors with different resistances are connected in series, which of the following must be the same for each resistor? Choose all correct answers (1) Potential difference (2) Current (3) Power delivered (4) Charge entering

(2) and (4)

A capacitor has capacitance C. Without disconnecting the battery the two plates are separated until they are twice as far apart as originally. What happens to the voltage across the plates? (1) Voltage goes up (2) Voltage goes down (3) The voltage stays the same (4) Need more information

(3)

An electromagnetic wave propagates in the negative y direction. The electric field at a point in space is momentarily oriented in the positive x direction. In which direction is the magnetic field at the point momentarily oriented? (A) the -x direction (B) the +y direction (C) the +z direction (D) the -z direction

(C)

A bar moves on rails to the right with a velocity v, and a uniform, constant, magnetic field is directed out of the page. Which of the following statements are correct? (1) The induced current in loop is zero (2) The induced current in the loop is clockwise (3) The induced current in the loop is counterclockwise (4) An external force is required to keep the bar moving at constant speed (5) No force is required to keep the bar moving at constant speed

(2) and (4)

When resistors with different resistances are connected in parallel, which of the following must be the same for each resistor? Choose all correct answers (1) Potential difference (2) Current (3) Power delivered (4) Charge entering

(1)

Your younger brother likes to rub his feet on the carpet and then touch you to give you a shock. While you are trying to escape the shock treatment, you discover a hollow metal cylinder in your basement, large enough to climb inside. In which of the following cases will you not be shocked? (1) You climb inside the cylinder, making contact with the inner surfaces and your charged brother touches the outside of the metal surface (2) Your charged brother is inside touching the inner metal surface and you are outside, touching the outer metal surface (3) Both of you are outside the cylinder, touching its outer metal surface but not touching each other directly

(1)

A flat coil of wire is placed in a uniform magnetic field that is in the y direction. The magnetic flux through the coil is a zero if the plane of the coil is: (1) In the xy plane (2) In the yz plane (3) In the xz plane (4) In any orientation, because it is constant

(1) and (2)

A capacitor with capacitance C is connected to a battery until charged, then disconnected from the battery. A dielectic having constant K is inserted in the capacitor. What changes occur in the charge, potential, and stored energy of the capacitor after the dielectric is inserted? (1) ΔV same, Q increases, U increases (2) ΔV same, Q decreases, U same (3) ΔV increases, Q decreases, U increases (4) ΔV decreases, Q same, U increases (5) ΔV same, Q decreases, U decreases (6) Cannot be determined (7) None of the above

(4)

A capacitor, C1, is connected to a battery until charged, then disconnected from the battery. A second capacitor, C2, is connected in parallel to the first capacitor. Which statements below are true? (1) Charge on C1 decreases (2) Total charge on C1 and C2 is the same as the original Q (3) The total energy stored in both capacitors is the same U stored in C1 (4) The potential difference (Voltage) across C1 decreases (5) 1, 2, and 4 are true (6) All of the above (7) 1, 2, and 3 are true (8) None of the above

(5)

Two uniformly charged rods are positioned horizontally. The top rod is positively charged and the bottom rod is negatively charged. The total electric field at the origin... (1) is zero (2) has both a non-zero x component and a non-zero y component (3) points totally in the -x direction (4) points totally in the +x direction (5) points totally in the -y direction (6) points totally in the +y direction (7) points in a direction impossible to determine without doing a lot of math

(5)

All charged rods have the same length and the same linear charge density (+ or -). Light rods are positively charged, and dark rods are negatively charged. For which arrangement below would the magnitude of the electric field at the origin be the largest?

(6)

A capacitor, C1, is connected to a battery until charged, and then disconnected from the battery, A second capacitor, C2, is connect in series to the first capacitor. What changes occur in the capacitor C1 after C2 is connected and shown? (1) ΔV same, Q increases, U increases (2) ΔV same, Q decreases, U same (3) ΔV increases, Q decreases, U increases (4) ΔV decreases, Q same, U decreases (5) ΔV same, Q decreases, U decreases (6) Cannot be determined (7) None of the above

(7)

A radio wave of frequency on the order of 105 Hz is used to carry a sound wave with a frequency on the order of 103 Hz. Is the wavelength of this radio wave in the order of (A) km (B) m (C) cm (D) um

(A)

There are 4 cases. A Gaussian surface surrounds the charged particle in each case. Case 1: q and R Case 2: 2q and R Case 3: q and 2R Case 4: 2q and 2R Considering the electric flux through each of the Gaussian surfaces, which of the following comparative statements is correct? (A) 2 = 4 > 1 = 3 (B) 1 = 3 > 2 = 4 (C) 2 = 1 > 3 = 4 (D) 3 = 4 > 2 = 1 (E) 4 > 3 > 2 > 1

(A)

In the figure, a third resistor is added in parallel with the first two. What happens to the current in the battery? (A) increases (B) decreases (C) remains the same

(A) 1/Req = 1/R1 + 1/R2... I = V/Req

In an AC generator, a coil with N turns of wire spins in a magnetic field. Of the following choices, which does NOy cause an increase in the emf generated in the coil? (A) Replacing the coil wire with one of lower resistance (B) Spinning the coil faster (C) Increasing the magnetic field (D) Increasing the number of turns of wire on the coil

(A) Emax = NABw

The North Pole of a bar magnet is held steady close to an iron screw. The screw is... (A) Attracted by the magnet (B) Repelled by the magnet (C) Experiencing a force perpendicular to the line connecting the plastic and the magnet (D) Experiencing a force parallel to the line connecting the plastic and the magnet (E) Unaffected by the magnet

(A) Iron can be magnetized

A test charge of +3 µC is at a point P where the electric field due to the other charges is directed to the right and has a magnitude of 4 * 10^6 N/C. If the test charge is replaced with a charge of -3 µC, what happens to the electric field at P? (A) It is unaffected (B) It reverses direction (C) It changes in a way that cannot be determined

(A) It is unaffected

A current carrying ohmic metal wire has a cross-sectional area that gradually becomes smaller from one end of the wire to the other. The current has the same value for each section of the wire, so charge does not accumulate at any one point. How does the resistance per unit length vary along the wire as the area becomes smaller? (A) It increases (B) It decreases (C) It remains constant

(A) R/L = roe/A

We construct a closed Gaussian surface in the shape of a spherical balloon. Assume that a small glass with total charge Q is in the vicinity of the balloon. Consider the following statements: (A) If the bead is inside the balloon, the electric flux over the balloon's surface can never be 0. (B) If the bead is outside the balloon, the electric flux over the balloon surface must be zero. Which statement(s) are valid?

(A) and (B)

To maximize the percentage of the power from the emf of a battery that is delivered to a device external to the battery, what should the internal resistance of the battery be? (A) as low as possible (B) as high as possible (C) The percentage does not depend on the internal resistance

(A) low

The circles in the picture below are Gaussian surfaces. All other lines are electric field lines. For which cases is the flux non-zero? *If unable to see picture, sorry :(*

(A), (B), and (F)

Three objects are brought close to each other, two at a time. When objects A and B are brought together, they repel. When objects B and C are brought together, they also repel. Which of the following are true? *Can be more than one answer* (A) Objects A and C possess charges of the same sign (B) Objects A and C possess charges of opposite sign (C) All three objects possess charges of the same sign (D) One object is neutral (E) Additional experiments must be performed to determine the signs of the charges

(A), (C), and (E)

Object A has a charge of +2 µC, and object B has a charge of +6 µC. Which statement is true? (A) Fab = - 3Fba (B) Fab = - Fba (C) 3Fab = - Fba (D) Fab = 3Fba (E) Fab = Fba (F) 3Fab = Fba

(B)

The figure shows a Gaussian cube of face area A. A point particle with charge q is places at the center of the cube. The electric flux through the cube is... (A) Psi = q(enc)/6E0 (B) Psi = q(enc)/E0 (C) Psi = 0 (D) Psi = q(enc)/16E0 (E) Need more information

(B)

To maximize the radiation pressure on the sails of a spacecraft using solar sailing, should the sheets be (A) very black to absorb as much sunlight as possible (B) very shiny to reflect as much sunlight as possible

(B)

In the figure, as the applied voltage increases, does the resistance of the diode (A) increase (B) decrease (C) remain the same Image shows a graph of I vs. ΔV parabola curved upward

(B) R = ΔV / I

In the figure, a third resistor is added in series with the first two. What happens to the current in the battery? (A) increase (B) decrease (C) remain same

(B) Req = R1 + R2... I = V/Req

You wish to start a fire by reflecting sunlight from a mirror onto some paper under a pile of wood. Which would be the best choice for the type of mirror? (A) flat (B) concave (C) convex

(B) concave

Consider the circuit with S1 open and S2 closed. Switch S1 s now thrown closed. At the instant it is closed, across which circuit element is the voltage equal to the emf of the battery? (A) The resistor (B) The inductor (C) Both

(B) the inductor

A triangular aluminum loop is slowly moving to the right. Eventually, it will enter the magnetic field region represented by the tails of arrows directed away from you, Initially, there is no current in the loop. When the loop is entering the magnetic field, what will be the direction of any induced current present in the loop? (A) Clockwise (B) Counterclockwise (C) No current is induced

(B), magnetic flux is increasing

A charged particle is moving perpendicular to a magnetic field in a circle with a radius r. An identical particle enters the field, with v perpendicular to B, but with a higher speed than the first particle. Compared the the radius for the first particle, is the radius of the circular path for the second particle (A) smaller (B) larger (C) equal in size

(B), r = mv/|q|B

A physics student desires to create a beam of light that consists of parallel rays. Which of the following arrangements would allow her to accomplish this task? (A) A light bulb is placed at the focal point of a convex mirror (B) A light bulb is placed at the focal point of a diverging lens (C) A light bulb is placed at the focal point of a converging lens (D) A light bulb is located at twice the focal length from a concave mirror (E) A light bulb is located at twice the focal length from a converging lens

(C)

At a certain instant, a proton is moving in the positive x direction through a magnetic field in the negative z direction. What is the direction of the magnetic force exerted on the proton? (A) positive z direction (B) negative z direction (C) positive y direction (D) negative y direction (E) F = 0

(C)

In many kitchens, a microwave oven is used to cook food. The frequency of the microwaves is on the order of 10^10 Hz. Are the wavelengths of these microwaves on the order of (A) km (B) m (C) cm (D) um

(C)

Light passes from a material with index of refraction 1.3 into one with index of refraction 1.2. Compared to the incident ray, what happens to the refracted ray? (A) It bends towards the normal (B) It is undeflected (C) It bends away from the normal

(C)

Way is the phase difference between the sinusoidal oscillations of the electric and magnetic fields in the figure? (A) 180 (B) 90 (C) 0

(C)

When a particle with a charge Q is surrounded by a spherical Gaussian surface, the electric flux through the surface is Psi(s). Consider what would happen if the particle was surrounded by a cylindrical Gaussian surface or Gaussian cube. How would the fluxes through the cylindrical Psi(Cyl) and cubic Psi(cubic) surfaces compare to Psi(s)? (A) Psi(s) = Psi(cubic) > Psi(cyl) (B) Psi(s) > Psi(cyl) = Psi(cubic) (C) Psi(s) = Psi(cyl) = Psi(cubic) (D) Psi(s) < Psi(cubic) < Psi(cyl) (E) Psi(s) > Psi(cubic) > Psi(cyl)

(C) *Shape never matters*

In the figure, take q2 to be a negative source charge and q1 to be a second charge whose sign can be changed. If q1 is initially positive and is changed to a charge of the same magnitude but negative, what happens to the potential at the position of q1 due to q2? (A) It increases (B) It decreases (C) It remains the same

(C) It remains the same

A spatially uniform magnetic field cannot exert a magnetic force on a particle in which of the following circumstances? *May be more than one answer* (A) The particle is charged (B) The particle moves perpendicular to the magnetic field (C) The particle move parallel to the magnetic field (D) The magnitude of the magnetic field changes with time (E) The particle is at rest

(C) and (E)

The force is proportional to the magnitude of the field exerting it for (A) electric forces (B) magnetic forces (C) both electric and magnetic forces (D) neither electric nor magnetic forces

(C) both

A capacitor has a capacitance C and is charged using a battery. After disconnecting the battery the two plates are separated until they are twice as far apart as originally. What happens to the charge stored? (A) charge goes up (B) charge goes down (C) charge stays the same (D) need more information

(C) charge stays the same

Consider a solenoid that is very long compared with its radius. Of the following choices, what is the most effective way to increase the magnetic field in the interior of the solenoid? (A) Double its length and # turns per unit length stays constant (B) Reduce its radius by half, keeping the # turns per unit length constant (C) Overwrap the entire solenoid with an additional layer of current-carrying wire

(C), B = Usub0*n*i

A capacitor with very large capacitance is in series with another capacitor with very small capacitance, What is the equivalent capacitance of the combination? (A) Slightly greater than the capacitance of the large capacitor (B) Slightly less than the capacitance of the large capacitor (C) Slightly greater than the capacitance of the small capacitor (D) Slightly less than the capacitance of the small capacitor

(D)

In the movies, you sometimes see an actor looking in a mirror and you can see his face in the mirror. It can be said with certainty that during the filming of such a scene, the actor sees in the mirror: (A) his face (B) your face (C) the director's face (D) the movie camera (E) Need more info

(D)

Car batteries are often rated in ampere-hours. The info designates the amount of ____ that the battery can supply (A) Current (B) Power (C) Energy (D) Charge (E) Potential

(D) Charge

The force exerted on a moving charged object is zero for (A) electric forces (B) magnetic forces (C) both electric and magnetic forces (D) neither electric nor magnetic forces

(D) neither

An electron moves in the plane of this screen towards the top of the screen. A magnetic field is also in the plane of the screen and directed towards the right. What is the direction of the magnetic force on the electron? (A) Toward the top of the screen (B) Toward the bottom of the screen (C) Toward the left edge of the screen (D) Toward the right edge of the screen (E) Out of the screen (F) Into the screen

(E)

Three objects are brought close to one another, two at a time. When objects A and B are brought together, they attract. When objects B and C are brought together, they repel. Which of the following are necessarily true? *Can be more than one answer* (A) Objects A and C possess charges of the same sign (B) Objects A and C possess charges of opposite sign (C) All three objects possess charges of the same sign (D) One object is neutral (E) Additional experiments must be performed to determine information about the charges on the objects

(E)

The North Pole of a bar magnet is held steady close to a piece of plastic. The plastic is... (A) Attracted by the magnet (B) Repelled by the magnet (C) Experiencing a force perpendicular to the line connecting the plastic and the magnet (D) Experiencing a force parallel to the line connecting the plastic and the magnet (E) Unaffected by the magnet

(E) Plastic cannot be magnetized

The North Pole of a bar magnet is held steady close to a positively charged piece off plastic. The plastic is... (A) Attracted by the magnet (B) Repelled by the magnet (C) Experiencing a force perpendicular to the line connecting the plastic and the magnet (D) Experiencing a force parallel to the line connecting the plastic and the magnet (E) Unaffected by the magnet

(E) the charged rod is not in motion

In an RC circuit, the capacitor begins to discharge. During the discharge, in the region of space between the plates of the capacitor, is there (a) conduction current but no displacement current (b) displacement current but no conduction current (c) both conduction and displacement current (d) no current of any type (e) an electric field but no magnetic field (f) a magnetic field but no electric field (g) both electric and magnetic fields (h) no fields of any type

(b), (g)

An electron moves with velocity v along the positive y axis and magnetic flux B along the positive x axis. The magnetic force on the electron is in which direction? (a) Toward the left (b) Toward the right (c) Toward the bottom (d) Out of the plane (e) Into the plane

(d)

Which of the following best describes images formed by diverging lens? (a) always smaller than the object (b) always larger than the object (c) always inverted (d) always virtual (e) always real

(d)

Rank the potential energies of the four systems of particles shown in figure from largest to smallest. Include equalities if appropriate. Case 1: +Q, r, and +2Q Case 2: -Q, r, and -Q Case 3: Q, 2r, and -Q Case 4: -Q, 2r, and -2Q Hint: U = keq1q2/r

1 > 2 = 4 > 3

Four magnetic moments are shown in a uniform magnetic field. B is moving directly toward positive x. All magnetic moments have the same angle with B. 1 is moving diagonally left and upward 2 is moving diagonally right and upward 3 is moving diagonally right and downward 4 is moving diagonally left and downward Which moments feel the largest in magnitude torque?

All tie

What is inverted in the virtual image in a plane mirror?

Back and front

Two identical batteries are connected to two identical inductors in two different circuits. The switches are closed for a very long time. At t = 0, both switches are opened. Which resistor dissipates more total energy after the switch is opened, the 1ohm or 2 ohm?

Both resistors dissipate the same amount of energy. 1ohm make take longer but the total amount will be the same

A circular loop wire falls downward towards a wore carrying a current to the left. What is the direction of the induced current in the loop of the wire?

Counterclockwise

Does magnetic flux change if the speed is constant and a loop inside the magnetic field does not exit the field?

No

A rigid, circular metal loop begins at rest in a uniform magnetic field directed away from you as shown. The loop is then pulled through the field toward the right, but does not exit the field. What is the direction of any induced current within the loop?

No current is induced

A wire carries current in the plane of this screen toward the top of the screen. The wire experiences a magnetic force toward the right edge of the screen. The direction of the magnetic field is causing this force to move...

Out of the screen

What type of image is formed when an object is placed at a distances greater than the focal point in a concave mirror?

Real

Two coils are placed near each other as shown in the figure. The coil on the left is connected to a battery and a switch, and the coil on the right is connected to a resistor. What is the direction of the current in the resistor at an instant immediately after the switch is thrown closed?

Right

Cat's eyes have pupils that can be modeled as vertical slits. At night, would cats be more successful is resolving headlights on a distant car or vertically separated lights on the mast of a distant boat?

Vertically separated lights

Suppose a slit width is made half as wide. The central bright fringe will become

Wider