PHYS2002 Cumulative Final Exam Conceptual Questions
Units of Newtons (N)
kg*m/s^2
Units of Joules (J)
kg*m^2*s^2 N*m W*s C*V
When a positive charge is released and moves along an electric field line, it moves to a position of a. lower potential and lower potential energy. b. lower potential and higher potential energy. c. higher potential and lower potential energy. d. higher potential and higher potential energy. e. greater magnitude of the electric field.
lower potential and lower potential energy.
When two or more different capacitors are connected in parallel across a potential source (battery), which of the following statements must be true? (There could be more than one correct choice.) A) The potential difference across each capacitor is the same. B) Each capacitor carries the same amount of charge. C) The equivalent capacitance of the combination is less than the capacitance of any one of the capacitors. D) The capacitor with the largest capacitance has the largest potential difference across it. E) The capacitor with the largest capacitance has the most charge.
A) The potential difference across each capacitor is the same. E) The capacitor with the largest capacitance has the most charge.
Coil A is close to, but not touching, coil B. If a steady counterclockwise 100-A current flows in coil A, what can you say about the induced current in coil B? A) There will be no induced current in coil B. B) The current in coil B will be equal to 100 A clockwise. C) The current in coil B will be equal to 100 A counterclockwise. D) The current in coil B will be counterclockwise and less than 100 A, but not zero. E) The current in coil B will be clockwise and less than 100 A, but not zero.
A) There will be no induced current in coil B.
An electron has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component A) to the west. B) to the east. C) upward. D) downward. E) to the north
A) to the west.
Two long, parallel wires carry currents of different magnitudes. If the current in one of the wires is doubled and the current in the other wire is halved, what happens to the magnitude of the magnetic force that each wire exerts on the other? A) It is doubled. B) It stays the same. C) It is tripled. D) It is quadrupled. E) It is reduced by a factor of two
B) It stays the same.
Three identical capacitors are connected in series across a potential source (battery). If a charge of Q flows into this combination of capacitors, how much charge does each capacitor carry? A) 3Q B) Q C) Q/3 D) Q/9
B) Q
A resistor and an inductor are connected in series to an ideal battery of constant terminal voltage. At the moment contact is made with the battery, the voltage across the inductor is A) greater than the battery's terminal voltage. B) equal to the battery's terminal voltage. C) less than the battery's terminal voltage, but not zero. D) zero. E) equal to the voltage across the resistor.
B) equal to the battery's terminal voltage.
Suppose you have two capacitors and want to use them to store the maximum amount of energy by connecting them across a voltage source. You should connect them A) in series across the source. B) in parallel across the source. C) It doesn't matter because the stored energy is the same either way.
B) in parallel across the source.
Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions. The wire on your right carries current directly toward you, and the wire on your left carries current directly away from you. From your point of view, the magnetic field at a point exactly midway between the two wires A) points upward. B) points downward. C) points toward you. D) points away from you. E) is zero.
B) points downward.
Kirchhoff's junction rule is a statement of A) the law of conservation of momentum. B) the law of conservation of charge. C) the law of conservation of energy. D) the law of conservation of angular momentum. E) Newton's second law.
B) the law of conservation of charge.
When different resistors are connected in parallel across an ideal battery, we can be certain that A) the same current flows in each one. B) the potential difference across each is the same. C) the power dissipated in each is the same. D) their equivalent resistance is greater than the resistance of any one of the individual resistances. E) their equivalent resistance is equal to the average of the individual resistances.
B) the potential difference across each is the same.
When different resistors are connected in parallel across an ideal battery, we can be certain that A) the same current flows in each one. B) the potential difference across each is the same. C) the power dissipated in each is the same. D) their equivalent resistance is greater than the resistance of any one of the individual resistances. E) their equivalent resistance is equal to the average of the individual resistances.
B) the potential difference across each is the same.
A proton has an initial velocity to the south but is observed to curve upward as the result of a magnetic field. This magnetic field must have a component A) to the west. B) to the east. C) upward. D) downward. E) to the north.
B) to the east.
A resistor and an inductor are connected in series to a battery. The time constant for the circuit represents the time required for the current to reach A) 25% of the maximum current. B) 37% of the maximum current. C) 63% of the maximum current. D) 75% of the maximum current. E) 100% of the maximum current.
C) 63% of the maximum current.
Three identical capacitors are connected in parallel to a potential source (battery). If a charge of Q flows into this combination, how much charge does each capacitor carry? A) 3Q B) Q C) Q/3 D) Q/9
C) Q/3
Which one of the following statements is correct? A) Earth's geographic north pole is the north pole of Earth's magnetic field. B) Earth's geographic south pole is the south pole of Earth's magnetic field. C) The north pole of a magnet points towards Earth's geographic north pole. D) The north pole of a magnet points towards Earth's geographic south pole. E) None of the above statements is correct.
C) The north pole of a magnet points towards Earth's geographic north pole.
A negatively-charged particle moves across a constant uniform magnetic field that is perpendicular to the velocity of the particle. The magnetic force on this particle A) causes the particle to speed up. B) causes the particle to slow down. C) causes the particle to accelerate. D) is in the same direction as the particle's velocity. E) is opposite the direction of the particle's velocity.
C) causes the particle to accelerate.
If you were to cut a small permanent bar magnet in half, A) one piece would be a magnetic north pole and the other piece would be a south pole. B) neither piece would be magnetic. C) each piece would in itself be a smaller bar magnet with both north and south poles. D) None of these statements is true
C) each piece would in itself be a smaller bar magnet with both north and south poles.
A charged particle moves with a constant speed through a region where a uniform magnetic field is present. If the magnetic field points straight upward, the magnetic force acting on this particle will be strongest when the particle moves A) straight upward. B) straight downward. C) in a plane parallel to Earth's surface. D) upward at an angle of 45° above the horizontal.
C) in a plane parallel to Earth's surface.
A transformer is a device used to A) transform an alternating current into a direct current. B) transform a direct current into an alternating current. C) increase or decrease an ac voltage. D) increase or decrease a dc voltage.
C) increase or decrease an ac voltage.
A charged particle that is moving in a static uniform magnetic field A) will always experience a magnetic force, regardless of its direction of motion. B) may experience a magnetic force which will cause its speed to change. C) may experience a magnetic force, but its speed will not change. D) may experience a magnetic force, but its direction of motion will not change. E) None of the above statements are true.
C) may experience a magnetic force, but its speed will not change.
The direction of the force on a current-carrying wire in a magnetic field is A) perpendicular only to the current. B) perpendicular only to the magnetic field. C) perpendicular to both the current and the magnetic field. D) in the direction opposite to the current. E) in same direction as the current.
C) perpendicular to both the current and the magnetic field.
At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is A) zero. B) upward. C) toward the north. D) toward the south. E) downward.
C) toward the north.
You obtain a 100-W light bulb and a 50-W light bulb. Instead of connecting them in the normal way, you devise a circuit that places them in series across normal household voltage. If each one is an incandescent bulb of fixed resistance, which statement about these bulbs is correct? A) Both bulbs glow with the same brightness, but less than their normal brightness. B) Both bulbs glow with the same brightness, but more than their normal brightness. C) The 100-W bulb glows brighter than the 50-W bulb. D) The 50-W bulb glows more brightly than the 100-W bulb.
D) The 50-W bulb glows more brightly than the 100-W bulb.
We observe that a moving charged particle experiences no magnetic force. From this we can definitely conclude that A) no magnetic field exists in that region of space. B) the particle must be moving parallel to the magnetic field. C) the particle is moving at right angles to the magnetic field. D) either no magnetic field exists or the particle is moving parallel to the field. E) either no magnetic field exists or the particle is moving perpendicular to the field
D) either no magnetic field exists or the particle is moving parallel to the field.
The magnetic force on a current-carrying wire in a magnetic field is the strongest when A) the current is in the direction of the magnetic field lines. B) the current is in the direction opposite to the magnetic field lines. C) the current is at a 180° angle with respect to the magnetic field lines. D) the current is perpendicular to the magnetic field lines. E) the current is at a 0° angle with respect to the magnetic field lines.
D) the current is perpendicular to the magnetic field lines.
At a particular instant, an electron moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is A) zero. B) upward. C) toward the north. D) toward the south. E) downward.
D) toward the south.
A vertical wire carries a current straight up in a region where the magnetic field vector points toward the north. What is the direction of the magnetic force on this wire? A) downward B) toward the north C) toward the east D) toward the west E) upward F) toward the south
D) toward the west
A resistor, an uncharged capacitor, a dc voltage source, and an open switch are all connected in series. The switch is closed at time t = 0 s. Which one of the following is a correct statement about the circuit? A) The capacitor charges to its maximum value in one time constant. B) The capacitor charges to its maximum value in two time constants. C) The potential difference across the resistor is always equal to the potential difference across the capacitor. D) Current flows through the circuit even after the capacitor is essentially fully charged. E) Once the capacitor is essentially fully charged, there is no current in the circuit.
E) Once the capacitor is essentially fully charged, there is no current in the circuit.
Equation for displacement current
Id = d/dt Q where Q = Qo * e^(-t/RC)
When distance between two charged objects is tripled the electric force between them a) becomes twice as large. b) remains the same. c) becomes half as large. d) becomes ¼ as large. e) None of the above.
e) None of the above.
Gauss's law is useful for calculating electric fields that are a) Symmetric. b) Uniform. c) Due to point charges. d) Due to continuous charges
a) Symmetric
Two charges are fixed along the x axis. They produce an electric field E directed along the negative y axis along the perpendicular bisector. Which of the following is true? a) charges are equal and positive (if the chosen point is below the x-axis) b) charges are equal and negative (if the chosen point is above the x-axis) c) charges are equal and opposite d) charges are equal, but sign is undetermined e) None of the above
a) charges are equal and positive (if the chosen point is below the x-axis) b) charges are equal and negative (if the chosen point is above the x-axis)
A conductor of radius r, length , and resistivity ρ has resistance R. It is melted down and formed into a new conductor, also cylindrical, with one fourth the length of the original conductor. The resistance of the new conductor is a. 1/16R b. 1/4R c. R d. 4R e. 16R
a. 1/16R
Two mirrors are at right angles to one another. If an object is placed near the mirrors, what is the largest number of images that would be seen in the mirrors? a. 3 b. 2 c. 4 d. 5 e. 6
a. 3
A positively charged particle has a velocity in the negative z direction at point P. The magnetic force on the particle at this point is in the negative y direction. Which one of the following statements about the magnetic field at point P can be determined from this data? a. Bx is positive. b. Bz is positive. c. By is negative. d. By is positive. e. Bx is negative.
a. Bx is positive.
The magnetic field amplitude in an electromagnetic wave in vacuum is related to the electric field amplitude by B = a. E/c b. E/sqrt(c) c. E d. E*sqrt(c) e. cE
a. E/c
A magician can make a candle look as if it is burning under water by focusing light from a candle flame burning in air directly on top of an underwater candle. To do this you want to use a (Hint: eliminate those that cannot work.) a. a concave mirror farther than one focal length from the burning candle. b. a convex mirror farther than one focal length from the burning candle. c. a biconcave lens farther than one focal length from the burning candle. d. a concave mirror closer than one focal length to the burning candle. e. a convex lens closer than one focal length to the burning candle.
a. a concave mirror farther than one focal length from the burning candle.
Light behaves like a. a wave at times, and a particle at other times. b. a wave. c. a particle. d. both a wave and a particle, because of its dual nature.
a. a wave at times, and a particle at other times.
The algebraic sum of the changes of potential around any closed-circuit loop is a. zero. b. maximum. c. zero only if there are no sources of emf in the loop. d. maximum if there are no sources of emf in the loop. e. equal to the sum of the currents in the branches of the loop.
a. zero.
Can electric field lines intersect in free space? a) Yes, but only at the midpoint between a positive and a negative charge. b) No. c) Yes, but only at the midpoint between two equal like charges. d) Yes, but only at the centroid of an equilateral triangle with like charges at each corner.
b) No.
The electric field of a dipole is inversely proportional to the ________ of the distance. a) square b) cube c) fourth power d) fifth power
b) cube
The electric field outside of a uniformly charged sphere is most like a a) ring of charge b) point charge c) disk of charge d) parallel plate capacitor
b) point charge
A cook plugs a 500-W crockpot and a 1 000-W kettle into a 240-V power supply, all operating on direct current. When we compare the two, we find that a. Icrockpot < Ikettle and Rcrockpot < Rkettle. b. Icrockpot < Ikettle and Rcrockpot > Rkettle. c. Icrockpot = Ikettle and Rcrockpot = Rkettle. d. Icrockpot > Ikettle and Rcrockpot < Rkettle. e. Icrockpot > Ikettle and Rcrockpot > Rkettle.
b. Icrockpot < Ikettle and Rcrockpot > Rkettle.
Light bulb A is rated at 60 W and light bulb B is rated at 100 W. Both are designed to operate at 110 V. Which statement is correct? a. The 60-W bulb has a greater resistance and greater current than the 100-W bulb. b. The 60-W bulb has a greater resistance and smaller current than the 100-W bulb. c. The 60-W bulb has a smaller resistance and smaller current than the 100-W bulb. d. The 60-W bulb has a smaller resistance and greater current than the 100-W bulb. e. We need to know the resistivities of the filaments to answer this question.
b. The 60-W bulb has a greater resistance and smaller current than the 100-W bulb.
The following statements all refer to the human brain when mental activity is occurring. Which statement is correct? a. In order to detect electric currents in the brain, you must open the skull and make direct electrical contact with the brain. b. The electric currents in the brain can be detected outside the brain by detecting the magnetic fields they produce. c. The electric currents in the brain can be mapped by shaving a person's head and dropping iron filings on the head. d. The electric currents in the brain produce an aura that can be detected visually. e. The electric currents in the brain cannot be detected by any means.
b. The electric currents in the brain can be detected outside the brain by detecting the magnetic fields they produce.
If a convex lens were made out of very thin clear plastic filled with air, and were then placed underwater where n = 1.33 and where the lens would have an effective index of refraction n = 1, the lens would act in the same way a. as a concave mirror in air. b. as a concave lens in air. c. as a convex lens in air. d. as a flat refracting surface between water and air as seen from the water side. e. as the glasses worn by a farsighted person.
b. as a concave lens in air.
Which of the following type(s) of materials is(are) repelled when a magnet is brought near by? a. paramagnetic b. diamagnetic c. ferromagnetic d. paramagnetic and ferromagnetic e. paramagnetic, ferromagnetic, and diamagnetic
b. diamagnetic
The electric potential inside a charged solid spherical conductor in equilibrium a. is always zero. b. is constant and equal to its value at the surface. c. decreases from its value at the surface to a value of zero at the center. d. increases from its value at the surface to a value at the center that is a multiple of the potential at the surface. e. is equal to the charge passing through the surface per unit time divided by the resistance.
b. is constant and equal to its value at the surface.
On the average, in a ferromagnetic domain, permanent atomic magnetic moments are aligned ____ to one another. a. antiparallel b. parallel c. perpendicular d. alternately parallel and antiparallel e. randomly relative
b. parallel
The image of an object beneath the surface of a medium of refractive index n > 1 is seen in air by a person looking down on the surface. This image, formed by light rays leaving the flat refractive surface, is a. real and closer to the viewer than the object. b. virtual and closer to the viewer than the object. c. real and farther from the viewer than the object. d. virtual and farther from the viewer than the object. e. virtual and the same distance from the viewer as the object.
b. virtual and closer to the viewer than the object.
If a negative charged rod is held near a neutral metal ball, the ball is attracted to the rod. This happens a) Because of magnetic effects. b) Because the ball tries to pull the rod's electrons over to it. c) Because the rod polarizes the metal. d) Because the rod and the ball have opposite charges.
c) Because the rod polarizes the metal.
Materials in which the electrons are bound very loosely to the nuclei and can move about freely within the material are referred to as a) Insulators b) Semiconductors c) Conductors d) Superconductors e) None of the above
c) Conductors
The SI unit of the electric field is a) N. b) C/N. c) N/C. d) C. e) None of the above.
c) N/C
A particle with electric charge is fired into a region of space where the electric field is zero. It moves in a straight line. Can you conclude that the magnetic field in that region is zero? a) Yes, you can. b) No; the field might be perpendicular to the particle's velocity. c) No; the field might be parallel to the particle's velocity. d) No; the particle might need to have charge of the opposite sign to have a force exerted on it. e) No; an observation of an object with electric charge gives no information about a magnetic field.
c) No; the field might be parallel to the particle's velocity.
The SI unit for electric potential is a) N b) J c) V d) C
c) V
As an electron moves in the direction the electric field lines a) it is moving from low potential to high potential and gaining electric potential energy. b) it is moving from low potential to high potential and losing electric potential energy. c) it is moving from high potential to low potential and gaining electric potential energy. d) it is moving from high potential to low potential and losing electric potential energy. e) both its electric potential and electric potential energy remain constant.
c) it is moving from high potential to low potential and gaining electric potential energy.
The speed of light is given by the value of a. Eo * muo b. sqrt(Eo * muo) c. 1/sqrt(Eo * muo) d. 1/Eo * muo e. sqrt(Eo/muo)
c. 1/sqrt(Eo * muo)
Coaxial Cable A has twice the length, twice the radius of the inner solid conductor, and twice the radius of the outer cylindrical conducting shell of coaxial Cable B. What is the ratio of the inductance of Cable A to that of Cable B? a. 4 ln2 b. 2 ln2 c. 2 d. 2 ln4 e. 4 ln4
c. 2
Coil 1, connected to a 100 Ω resistor, sits inside coil 2. Coil 1 is connected to a source of 60 cycle per second AC current. Which statement about coil 2 is correct? a. No current will be induced in coil 2. b. DC current (current flow in only one direction) will be induced in coil 2. c. AC current (current flow in alternating directions) will be induced in coil 2. d. DC current will be induced in coil 2, but its direction will depend on the initial direction of flow of current in coil 1. e. Both AC and DC current will be induced in coil 2
c. AC current (current flow in alternating directions) will be induced in coil 2.
An induced emf is produced in a. a closed loop of wire when it remains at rest in a nonuniform static magnetic field. b. a closed loop of wire when it remains at rest in a uniform static magnetic field. c. a closed loop of wire moving at constant velocity in a nonuniform static magnetic field. d. all of the above. e. only (b) and (c) above.
c. a closed loop of wire moving at constant velocity in a nonuniform static magnetic field.
When light is either reflected or refracted, the quantity that does not change in either process is its a. direction of travel. b. dispersion. c. frequency. d. speed. e. wavelength
c. frequency.
When a negative charge is released and moves along an electric field line, it moves to a position of a. lower potential and lower potential energy. b. lower potential and higher potential energy. c. higher potential and lower potential energy. d. higher potential and higher potential energy. e. decreasing magnitude of the electric field.
c. higher potential and lower potential energy.
The difference between a DC and an AC generator is that a. the DC generator has one unbroken slip ring. b. the AC generator has one unbroken slip ring. c. the DC generator has one slip ring split in two halves. d. the AC generator has one slip ring split in two halves. e. the DC generator has two unbroken slip rings.
c. the DC generator has one slip ring split in two halves.
When a charged particle is moved along an electric field line, a. the electric field does no work on the charge. b. the electrical potential energy of the charge does not change. c. the electrical potential energy of the charge undergoes the maximum change in magnitude. d. the voltage changes, but there is no change in electrical potential energy. e. the electrical potential energy undergoes the maximum change, but there is no change in voltage.
c. the electrical potential energy of the charge undergoes the maximum change in magnitude.
A monochromatic (single frequency, single wavelength) light ray in air (n = 1) enters a glass prism (n = 1.5). In the glass prism a. both the frequency and the wavelength are the same as in air b. the frequency is the same, but the wavelength is greater than in air. c. the frequency is the same, but the wavelength is smaller than in air. d. the wavelength is the same, but the frequency is greater than in air. e. the wavelength is the same, but the frequency is smaller than in air.
c. the frequency is the same, but the wavelength is smaller than in air.
After a switch is thrown to remove the battery from a DC LR circuit, but the circuit is still left complete, the time constant represents a. the time rate of change of the current in the circuit. b. the time rate of change of the induced emf in the circuit. c. the magnitude of the ratio of the current to the time rate of change of the current. d. all of the above. e. only (a) and (b) above.
c. the magnitude of the ratio of the current to the time rate of change of the current.
When introduced into a region where an electric field is present, a proton with initial velocity will eventually move a. along an electric field line, in the positive direction of the line. b. along an electric field line, in the negative direction of the line. c. to a point of decreased potential. d. to a point of decreased potential. e. as described in both (a) and (c).
c. to a point of decreased potential.
A student has made the statement that the electric flux through one half of a Gaussian surface is always equal to the flux through the other half of the Gaussian surface. This is a. never true. b. never false. c. true whenever enclosed charge is symmetrically located at a center point, on a center line, or on a centrally placed plane. d. true whenever no charge is enclosed within the Gaussian surface. e. true only when no charge is enclosed within the Gaussian surface.
c. true whenever enclosed charge is symmetrically located at a center point, on a center line, or on a centrally placed plane.
Two concentric imaginary spherical surfaces of radius R and 2R respectively surround a positive point charge Q located at the center of the surfaces. When compared to the electric flux Φ1 through the surface of radius R, the electric flux Φ2 through the surface of radius 2R is a. Φ2 = 1/4Φ1 b. Φ2 = 1/2Φ1 c. Φ2 = Φ1 d. Φ2 = 2Φ1 e. Φ2 = 4Φ1
c. Φ2 = Φ1
When a dielectric material is introduced between the plates of a parallel-plate capacitor and completely fills the space, the capacitance increases by a factor of 4. What is the dielectric constant of the material that was introduced? a) 0.4 b) 1/4 c) 2 d) 4 e) None of the other choices is correct.
d) 4
A conductor is placed in an electric field under electrostatic conditions. Which of the following statements is correct for this situation? a) A certain fraction of the valence electrons go to the surface of the conductor. b) The electric field on the surface of the conductor is perpendicular to the surface. c) The electric field is zero inside the conductor d) All the above
d) All the above
A capacitor stores charge Q at a potential difference V. What happens if the voltage applied to the capacitor by a battery is doubled to 2 V? a) The capacitance falls to half its initial value, and the charge remains the same. b) The capacitance and the charge both fall to half their initial values. c) The capacitance and the charge both double. d) The capacitance remains the same, and the charge doubles.
d) The capacitance remains the same, and the charge doubles.
A capacitor stores charge Q at a potential difference ∆V. What happens if the voltage applied to the capacitor by a battery is doubled to 2 ∆V? a) The capacitance falls to half its initial value, and the charge remains the same. b) The capacitance and the charge both fall to half their initial values. c) The capacitance and the charge both double. d) The capacitance remains the same, and the charge doubles.
d) The capacitance remains the same, and the charge doubles.
A solid conducting sphere is placed in an external uniform electric field. With regard to the electric field on the sphere's interior, which statement is correct? a) The interior field points in a direction parallel to the exterior field. b) The interior field points in a direction perpendicular to the exterior field. c) The interior field points in a direction opposite to the exterior field. d) There is no electric field on the interior of the conducting sphere.
d) There is no electric field on the interior of the conducting sphere.
The SI unit of the electric potential is a) J. b) C/N. c) N/C. d) V e) None of the above.
d) V
Which of the following will increase the capacitance of a parallel-plate capacitor? (There could be more than one correct choice.) a) a decrease in the plate area and an increase in the plate separation b) a decrease in the potential difference between the plates c) an increase in the potential difference between the plates d) an increase in the plate area and a decrease in the plate separation e) an increase in the charge on the plates
d) an increase in the plate area and a decrease in the plate separation
When the distance between two charged objects is doubled the force between them a) becomes twice as large. b) remains the same. c) becomes half as large. d) becomes ¼ as large.
d) becomes ¼ as large.
High frequency alternating current is passed through a solenoid that contains a solid copper core insulated from the coils of the solenoid. Which statement is correct? a. A copper core remains cool no matter what the frequency of the current in the solenoid is. b. The copper core remains cool because the induced emf is parallel to the solenoid axis and fluctuates rapidly. c. The copper core heats up because an emf parallel to the solenoid axis is induced in the core. d. The copper core heats up because circular currents around its axis are induced in the core. e. The copper core heats up because the electric field induced in the copper is parallel to the magnetic field produced by the solenoid.
d. The copper core heats up because circular currents around its axis are induced in the core.
An initially uncharged parallel plate capacitor of capacitance C is charged to potential V by a battery. The battery is then disconnected. Which statement is correct? a. There is no charge on either plate of the capacitor. b. The capacitor can be discharged by grounding any one of its two plates. c. Charge is distributed evenly over both the inner and outer surfaces of the plates. d. The magnitude of the electric field outside the space between the plates is approximately zero. e. The capacitance increases when the distance between the plates increases.
d. The magnitude of the electric field outside the space between the plates is approximately zero.
Equipotentials are lines along which a. the electric field is constant in magnitude and direction. b. the electric charge is constant in magnitude and direction. c. maximum work against electrical forces is required to move a charge at constant speed. d. a charge may be moved at constant speed without work against electrical forces. e. charges move by themselves.
d. a charge may be moved at constant speed without work against electrical forces
When a switch is closed to complete a DC series RL circuit, a. the electric field in the wires increases to a maximum value. b. the magnetic field outside the wires increases to a maximum value. c. the rate of change of the electric and magnetic fields is greatest at the instant when the switch is closed. d. all of the above are true. e. only (a) and (c) above are true.
d. all of the above are true.
A current may be induced in a coil by a. moving one end of a bar magnet through the coil. b. moving the coil toward one end of the bar magnet. c. holding the coil near a second coil while the electric current in the second coil is increasing. d. all of the above. e. none of the above.
d. all of the above.
An inductor produces a back emf in a DC series RL circuit when a switch connecting the battery to the circuit is closed. We can explain this by a. Lenz's law. b. increasing magnetic flux within the coils of the inductor. c. increasing current in the coils of the inductor. d. all of the above. e. only (a) and (c) above.
d. all of the above.
At every instant the ratio of the magnitude of the electric to the magnetic field in an electromagnetic wave in vacuum is equal to a. the speed of radio waves. b. the speed of light. c. the speed of gamma rays. d. all of the above. e. only (a) and (b) above.
d. all of the above.
Magnetic fields are produced by a. constant electric currents. b. electric currents that vary sinusoidally with time. c. time-varying electric fields. d. all of the above. e. only (a) and (b) above
d. all of the above.
By using a compass to measure the magnetic field direction at various points adjacent to a long straight wire, you can show that the wire's magnetic field lines are a. straight lines in space that go from one magnetic charge to another. b. straight lines in space that are parallel to the wire. c. straight lines in space that are perpendicular to the wire. d. circles that have their centers on the wire and lie in planes perpendicular to the wire. e. circles that have the wire lying along a diameter of the circle.
d. circles that have their centers on the wire and lie in planes perpendicular to the wire.
The magnetic flux through a loop perpendicular to a uniform magnetic field will change a. if the loop is replaced by two loops, each of which has half of the area of the original loop. b. if the loop moves at constant velocity while remaining perpendicular to and within the uniform magnetic field. c. if the loop moves at constant velocity in a direction parallel to the axis of the loop while remaining in the uniform magnetic field. d. if the loop is rotated through 180 degrees about an axis through its center and in the plane of the loop. e. in none of the above cases.
d. if the loop is rotated through 180 degrees about an axis through its center and in the plane of the loop.
If you stand closer to a concave mirror than a distance of one focal length, the image you see is a. real and inverted. b. real and upright. c. virtual and inverted. d. virtual and upright. e. none of the above because you do not get an image.
d. virtual and upright.
When you stand in front of a convex mirror, the image you see is a. real and inverted. b. real and upright. c. virtual and inverted. d. virtual and upright. e. real and inverted if your distance from the mirror is greater than two focal lengths.
d. virtual and upright.
A metal ball hangs from the ceiling by an insulating thread. The ball is attracted to a negative-charged rod held near the ball. The charge of the ball must be: a) Positive b) Negative c) Neutral d) negative or neutral e) positive or neutral
e) positive or neutral
Jadeen says that you can increase the resistance of a copper wire by hammering the wire to make it narrower and longer. Arnell says that you can increase its resistance by heating the wire. Which one, if either, is correct, and why? a. Arnell, because the conductivity of the wire increases when it is heated. b. Arnell, because the conductivity of the wire decreases when it is heated. c. Jadeen, because the conductivity of a wire is directly proportional to its area and inversely proportional to its length. d. Jadeen, because the conductivity of a copper wire does not increase when it is hammered. e. Both are correct because (b) and (d) are both correct.
e. Both are correct because (b) and (d) are both correct.
Jim says that you can increase the resistance of a copper wire by hammering the wire to make it narrower and longer. Sara says that you can increase its resistance by heating the wire. Which one, if either, is correct, and why? a. Sara, because the conductivity of the wire increases when it is heated. b. Sara, because the conductivity of the wire decreases when it is heated. c. Jim, because the conductivity of a wire is directly proportional to its area and inversely proportional to its length. d. Jim, because the conductivity of a copper wire does not increase when it is hammered. e. Both are correct because (b) and (d) are both correct.
e. Both are correct because (b) and (d) are both correct.
The electric field in the region defined by the y-z plane and the negative x axis is given by E = −ax, where a is a constant. (There is no field for positive values of x.) As −x increases in magnitude, relative to V = 0 at the origin, the electric potential in the region defined above is a. a decreasing function proportional to −|x2|. b. a decreasing function proportional to −|x|. c. constant. d. an increasing function proportional to +|x|. e. an increasing function proportional to +|x2|.
e. an increasing function proportional to +|x2|.
In the atmosphere, the shortest wavelength electromagnetic waves are called a. microwaves. b. infrared waves. c. ultraviolet waves. d. X-rays. e. gamma rays
e. gamma rays
At a point in space where the magnetic field is measured, the magnetic field produced by a current element a. points radially away in the direction from the current element to the point in space. b. points radially in the direction from the point in space towards the current element. c. points in a direction parallel to the current element. d. points in a direction parallel to but opposite in direction to the current element. e. points in a direction that is perpendicular to the current element and perpendicular to the radial direction.
e. points in a direction that is perpendicular to the current element and perpendicular to the radial direction.
When a light ray travels between any two points, the path it takes is the one that (Hint: Eliminate answers you know are wrong.) a. covers the greatest distance. b. follows the greatest index of refraction. c. avoids travel in more than one medium. d. is the mean between the longest and the shortest paths. e. takes the least time.
e. takes the least time.
Equation for time delay (related to wavelength problems)
time delay = distance/c where c is speed of light