Q&A Hero

Q: The electric field in a region around the origin is given by , where Cis a constant. The equipotential surfaces are: A) concentric cylinders with axes along the zaxis B) concentric cylinders with axes along the xaxis C) concentric spheres centered at the origin D) planes parallel to the xyplane E) planes parallel to the yzplane

Q: The Earth's electric field creates a potential that increases 100 V for every meter of altitude.If an object of charge +4.5 mC and mass 68 g falls a distance of 1.0 m from rest under the influence of the Earth's electric and gravitational fields, what is its final kinetic energy? A) 0.22 J B) 0.45 J C) 0.67 J D) 1.1 J E) 7.2 J

Q: Two large parallel conducting plates are separated by a distance d, placed in a vacuum, and connected to a source of potential difference V. An oxygen ion, with charge 2e, starts from rest on the surface of one plate and accelerates to the other. If edenotes the magnitude of the electron charge, the final kinetic energy of this ion is: A) eV/2 B) eV/d C) eVd D) Vd/e E) 2eV

Q: An electron is accelerated from rest through a potential difference V. Its final speed is proportional to: A) V B) V2 C) D) 1/V E) 1/

Q: A particle with mass mand charge -qis projected with speed v0into the region between two parallel plates as shown. The potential difference between the two plates is Vand their separation is d. The change in kinetic energy of the particle as it traverses this region is:A) -qV/dB) C) qVD) E) none of these

Q: An electron goes from one equipotential surface to another along one of the four paths shown below. Rank the paths according to the work done by the electric field, from least to greatest. A) 1, 2, 3, 4 B) 4, 3, 2, 1 C) 1, then 3, then 4 and 2 tie D) 4 and 2 tie, then 3, then 1 E) 4, 3, 1, 2

Q: The work required to carry a particle with a charge of 6.0-C from a 5.0-V equipotential surface to a 6.0-V equipotential surface and back again to the 5.0-V surface is:A) 0 JB) 1.2 x10-5 JC) 3.0 x10-5 JD) 6.0 x10-5 JE) 6.0 x10-6 J

Q: During a lightning discharge, 30 C of charge move through a potential difference of 1.0 x108V in 2.0 x10-2s. The energy released by this lightning bolt is:A) 1.5 x1011JB) 3.0 x109JC) 6.0 x107JD) 3.3 x106JE) 1500 J

Q: The potential difference between two points is 100 V. If a particle with a charge of 2 C is transported from one of these points to the other, the magnitude of the work done is: A) 200 J B) 100 J C) 50 J D) 100 V E) 2 J

Q: If 500 J of work are required to carry a 40-C charge from one point to another, the potential difference between these two points is: A) 12.5 V B) 20,000 V C) 0.08 V D) depends on the path E) none of these

Q: An electron moves from point ito pointf,in the direction of a uniform electric field. During this motion: A) the work done by the field is positive and the potential energy of the electron-field system increases B) the work done by the field is negative and the potential energy of the electron-field system increases C) the work done by the field is positive and the potential energy of the electron-field system decreases D) the work done by the field is negative and the potential energy of the electron-field system decreases E) the work done by the field is positive and the potential energy of the electron-field system does not change

Q: Protons in the LHC accelerator in Geneva, Switzerland are accelerated to an energy of 4.0 TeV. What is this in joules? A) 6.4 x 10-19J B) 6.4 x 10-16J C) 6.4 x 10-13J D) 6.4 x 10-10J E) 6.4 x 10-7J

Q: A tiny sphere carrying a charge of 6.5 C sits in an electric field, at a point where the electric potential is 240 V. What is the sphere's potential energy? A) 2.7 x 10-8J B) 6.5 x 10-6J C) 1.6 x 10-3J D) 240 J E) 3.7 x 107J

Q: An electrically charged object creates an electric field. The electric potential due to this object: A) is a vector that points either towards or away from the object, depending on the sign of the charge B) is a vector that makes circular paths around the object C) is a non-negative scalar D) is a scalar but will be positive or negative depending on the sign of the charge E) points in the same direction as the field

Q: The fact that we can define electric potential energy means that: A) the electric force is nonconservative B) the electric force is conservative C) the work done on a charged particle depends on the path it takes D) there is a point where the electric potential energy is exactly zero E) it takes work for the electric force to move from some point ato some other point band back again

Q: An electron has charge "eand mass me. A proton has charge eand mass 1840me. A "proton volt" is equal to: A) 1eV B) 1840eV C) (1/1840)eV D) eV E) (1/) eV

Q: An electron volt is: A) the force acting on an electron in a field of 1 N/C B) the force required to move an electron 1 meter C) the energy gained by an electron in moving through a potential difference of 1 volt D) the energy needed to move an electron through 1 meter in any electric field E) the work done when 1 coulomb of charge is moved through a potential difference of 1 volt

Q: Positive charge Qis distributed uniformly throughout an insulating sphere of radius R, centered at the origin. A particle with a positive charge Qis placed at x= 2Ron the xaxis. The magnitude of the electric field at x= R/2 on the xaxis is:

Q: Charge Qis distributed uniformly throughout an insulating sphere of radius R. The magnitude of the electric field at a point R/2 from the center is:

Q: Positive charge Qis placed on a conducting spherical shell with inner radius R1and outer radius R2. The electric field at a point r<R1is:

Q: Positive charge Q is placed on a conducting spherical shell with inner radius R1and outer radius R2. A point charge q is placed at the center of the cavity. The magnitude of the electric field at a point outside the shell, a distance r from the center, is:

Q: Positive charge Qis placed on a conducting spherical shell with inner radius R1and outer radius R2. A point charge qis placed at the center of the cavity. The force on the charge qis: A) B) C) D) E) 0

Q: A solid insulating sphere of radius R contains a positive charge that is distributed with a volume charge density that does not depend on angle but does increase linearly with distance from the sphere center. Which of the graphs below correctly gives the magnitude E of the electric field as a function of the distance r from the center of the sphere?A) AB) BC) CD) DE) E

Q: Two large conducting parallel plates carry charge of equal magnitude, one positive and the other negative, that is distributed uniformly over their inner surfaces. Rank the points 1 through 5 according to the magnitude of the electric field at the points, least to greatest. A) 1, 2, 3, 4, 5 B) 5, 4, 3, 2, 1 C) 1 and 4 and 5 tie, then 2 and 3 tie D) 2 and 3 tie, then 1 and 4 tie, then 5 E) 2 and 3 tie, then 1 and 4 and 5 tie

Q: Two large insulating parallel plates carry positive charge of equal magnitude that is distributed uniformly over their inner surfaces. Rank the points 1 through 5 according to the magnitude of the electric field at the points, least to greatest. A) 1, 2, 3, 4, 5 B) 5, 4, 3, 2, 1 C) 1 and 4 and 5 tie, then 2 and 3 tie D) 2 and 3 tie, then 1 and 4 tie, then 5 E) 2 and 3 tie, then 1 and 4 and 5 tie

Q: Two large insulating parallel plates carry charge of equal magnitude, one positive and the other negative, that is distributed uniformly over their inner surfaces. Rank the points 1 through 5 according to the magnitude of the electric field at the points, least to greatest. A) 1, 2, 3, 4, 5 B) 5, 4, 3, 2, 1 C) 1and 4 and 5 tie, then 2 and 3 tie D) 2 and 3 tie, then 1 and 4 tie, then 5 E) 2 and 3 tie, then 1 and 4 and 5 tie

Q: Charge is distributed uniformly on the surface of a large flat plate. The electric field 2 cm from the plate is 30 N/C. The electric field 4 cm from the plate is: A) 120 N/C B) 60 N/C C) 30 N/C D) 15 N/C E) 7.5 N/C

Q: A long line of charge with “charge per unit length runs along the cylindrical axis of a cylindrical conducting shell which carries a charge per unit length of . The charge per unit length on the inner and outer surfaces of the shell, respectively are:

Q: Charge is distributed uniformly along a long straight wire. The electric field 2 cm from the wire is 20 N/C. The electric field 4 cm from the wire is: A) 120 N/C B) 80 N/C C) 40 N/C D) 10 N/C E) 5 N/C

Q: A 300-N/C uniform electric field points perpendicularly toward the left face of a large neutral conducting sheet. The area charge density on the left and right faces, respectively, are:A)-2.7 x10-9C/m2; +2.7 x10-9C/m 2B) +2.7 x10-9C/m2; -2.7 x10-9C/m 2C) -5.3 x10-9C/m2; +5.3 x10-9C/m 2D) +5.3 x10-9C/m2; -5.3 x10-9C/m 2E) 0 C/m2; 0 C/m2

Q: A conducting sphere of radius 0.01 m has a charge of 1.0 x10-9C deposited on it. The magnitude of the electric field just outside the surface of the sphere is:A) 0 N/CB) 450 N/CC) 900 N/CD) 4500 N/CE) 90,000 N/C

Q: Which of the following graphs represents the magnitude of the electric field as a function of the distance from the center of a solid charged conducting sphere of radius R? A) A B) B C) C D) D E) E

Q: A spherical conducting shell has charge Q. A particle with charge qis placed at the center of the cavity. The charge on the inner surface of the shell and the charge on the outer surface of the shell, respectively, are:A) 0, QB) q, Q- qC) Q, 0D) -q, Q+ qE) -q, 0

Q: Positive charge Qis placed on a conducting spherical shell with inner radius R1and outer radius R2. A point charge qis placed at the center of the cavity. The magnitude of the electric field at a point in the interior of the conductor a distance rfrom the center is:A) 0

Q: 10 C of charge are placed on a spherical conducting shell. A particle with a charge of -3C is placed at the center of the cavity. The net charge on the outer surface of the shell is:A) -7 CB) -3 CC) 0 CD) +3 CE) +7 C

Q: 10 C of charge are placed on a spherical conducting shell. A particle with a charge of -3 C is placed at the center of the cavity. The net charge on the inner surface of the shell is:A) -7 CB) -3 CC) 0 CD) +3 CE) +7 C

Q: A particle with charge +Q is placed outside a large neutral conducting sheet. At any point in the interior of the sheet the electric field produced by charges on the surface is directed:A) toward the surfaceB) away from the surfaceC) toward QD) away from QE) none of the above

Q: A hollow conductor is positively charged. A small uncharged metal ball is lowered by a silk thread through a small opening in the top of the conductor and allowed to touch its inner surface. After the ball is removed, it will have: A) a positive charge B) a negative charge C) no appreciable charge D) a charge whose sign depends on what part of the inner surface it touched E) a charge whose sign depends on where the small hole is located in the conductor

Q: A conducting sphere of radius 5.0 cm carries a net charge of 7.5 C. What is the surface charge density on the sphere? A) 2.4 x 10-2C/m2 B) 1.4 x 10-2C/m2 C) 9.5 x 10-4C/m2 D) 2.4 x 10-4C/m2 E) 6.0 x 10-5C/m2

Q: Positive charge Qis placed on a conducting spherical shell with inner radius R1 and outer radius R2. A particle with charge q is placed at the center of the cavity. The magnitude of the electric field at a point in the cavity, a distance rfrom the center, is:

Q: The outer surface of the cardboard center of a paper towel roll: A) is a possible Gaussian surface B) cannot be a Gaussian surface because it encloses no charge C) cannot be a Gaussian surface since it is an insulator D) cannot be a Gaussian surface since it is not closed E) none of the above

Q: Choose the INCORRECT statement: A) Gauss' law can be derived from Coulomb's law B) Gauss' law states that the net number of lines crossing any closed surface in an outward direction is proportional to the net charge enclosed within the surface C) Coulomb's law can be derived from Gauss' law and symmetry D) Gauss' law applies to a closed surface of any shape E) According to Gauss' law, if a closed surface encloses no charge, then the electric field must vanish everywhere on the surface

Q: Consider Gauss law: . Which of the following is true?A) must be the electric field due to the enclosed chargeB) If q= 0 then everywhere on the Gaussian surfaceC) If the three particles inside have charges of +q, +q and -2q,then the integral is zeroD) On the surface is everywhere parallel to E) If a charge is placed outside the surface, then it cannot affect at any point on the surface

Q: Charge Qis distributed uniformly throughout a spherical insulating shell. The net electric flux through the inner surface of the shell is:

Q: The table below gives the electric flux through the ends and round surfaces of four Gaussian surfaces in the form of cylinders. Rank the cylinders according to the charge inside, from the most negative to the most positive.left end right end rounded surfacecylinder 1: +2 x10-9N.m2/C +4 x10-9N.m2/C -6 x10-9N.m2/Ccylinder 2: +3 x10-9N.m2/C -2 x10-9N.m2/C +6 x10-9N.m2/Ccylinder 3: -2 x10-9N.m2/C -5 x10"9N.m2/C +3 x10-9N.m2/Ccylinder 4: +2 x10-9N.m2/C -5 x10"9N.m2/C -3 x10-9N.m2/CA) 1, 2, 3, 4B) 4, 3, 2, 1C) 3, 4, 2, 1D) 3, 1, 4, 2E) 4, 3, 1, 2

Q: Charge Qis distributed uniformly throughout a spherical insulating shell. The net electric flux through the outer surface of the shell is:

Q: A 3.5-cm radius hemisphere contains a total charge of 6.6x10-7C. The flux through the rounded portion of the surface is 9.8 x104N.m2/C. The flux through the flat base is:A) 0 N.m2/CB) +2.3 x104N.m2/CC) -2.3 x104N.m2/CD) -9.8 x104N.m2/CE) +9.8 x104N.m2/C

Q: A point particle with charge qis at the center of a Gaussian surface in the form of a cube. The electric flux through any one face of the cube is:

Q: A particle with charge 5.0C is placed at the corner of a cube. The total electric flux through all sides of the cube is:A) 0 N.m2/CB) 7.1 x104N.m2/CC) 9.4 x104N.m2/CD) 1.4 x105N.m2/CE) 5.6 x105N.m2/C

Q: A point particle with charge qis placed inside a cube but not at its center. The electric flux through any one side of the cube: E) cannot be computed using Gauss' law

Q: A physics instructor in an anteroom charges an electrostatic generator to 25 , then carries it into the lecture hall. The net electric flux through the lecture hall walls is:A) 0 N.m2/CB) 25 x10-6N.m2/CC) 2.2 x105N.m2/CD) 2.8 x106N.m2/CE) can't tell unless the lecture hall dimensions are given

Q: A point charge is placed at the center of a spherical Gaussian surface. The electric flux is changed if:A) the sphere is replaced by a cube of the same volumeB) the sphere is replaced by a cube of one-tenth the volumeC) the point charge is moved off center (but still inside the original sphere)D) the point charge is moved to just outside the sphereE) a second point charge is placed just outside the sphere

Q: A closed cylinder with a 0.15-m radius ends is in a uniform electric field of 300 N/C, perpendicular to the ends. The total flux through the cylinder is:A) 0 N.m2/CB) 4.2 N.m2/CC) 21 N.m2/CD) 280 N.m2/CE) can't tell without knowing the length of the cylinder

Q: Which statement is correct? A) The flux through a closed surface is always positive. B) The flux through a closed surface is always negative. C) The sign of the flux through a closed surface depends on an arbitrary choice of sign for the surface vector. D) Inward flux through a closed surface is negative and outward flux is positive. E) Inward flux through a closed surface is positive and outward flux is negative.

Q: A cylindrical wastepaper basket with a 0.15-m radius opening is in a uniform electric field of 300 N/C, perpendicular to the opening. The total flux through the sides and bottom is:A) 0 N.m2/CB) 4.2 N.m2/CC) 21 N.m2/CD) 280 N.m2/CE) can't tell without knowing the areas of the sides and bottom

Q: The flux of the electric field (24 N/C) + (30 N/C) + (16 N/C) through a 2.0 m2portion of the yzplane is:A) 32 N .m2/CB) 34 N .m2/CC) 42 N .m2/CD) 48 N .m2/CE) 60 N .m2/C

Q: When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N.m2/C. When the paper is turned 25°with respect to the field the flux through it is:A) 0 N.m2/CB) 11N.m2/CC) 12N.m2/CD) 23 N.m2/CE) 25 N.m2/C

Q: To calculate the flux through a curved surface, A) the area vector has to be perpendicular to the surface somewhere B) you must divide the surface into pieces that are tiny enough to be almost flat C) the surface must be spherical D) the surface cannot be curved very much; then you can treat it as though it were flat E) actually the flux through a curved surface cannot be calculated.

Q: The area vector for a flat surface: A) is parallel to the surface and has a magnitude equal to the length of a side of the surface. B) is perpendicular to the surface and has a magnitude equal to the length of a side of the surface. C) is parallel to the surface and has a magnitude equal to the area of the surface. D) is perpendicular to the surface and has a magnitude equal to the area of the surface. E) none of the above.

Q: The electric flux Φ through a surface: A) is the amount of electric field piercing the surface. B) is the electric field multiplied by the area. C) does not depend on the area involved. D) is the line integral of the electric field around the edge of the surface. E) is the amount of electric field skimming along the surface.

Q: Gauss's law: A) can always be used to calculate the electric field. B) relates the electric field throughout space to the charges distributed through that space. C) only applies to point charges. D) relates the electric field at points on a closed surface to the net charge enclosed by that surface. E) relates the surface charge density to the electric field.

Q: The diagram shows a particle with positive charge Qand a particle with negative chargeQ. The electric field at point P on the perpendicular bisector of the line joining them is: A)  B)  C)  D)  E) zero

Q: The diagrams below depict four different charge distributions. The charged particles are all the same distance from the origin. The electric field at the origin: A) is least for situation 1 B) is greatest for situation 3 C) is zero for situation 4 D) is downward for situation 1 E) is downward for situation 3

Q: Two point particles,with charges of q1and q2, are placed a distance rapart. The electric field is zero at a point P between the particles on the line segment connecting them. We conclude that: A) q1and q2must have the same magnitude and sign B) P must be midway between the particles C) q1and q2must have the same sign but may have different magnitudes D) q1and q2must have equal magnitudes and opposite signs E) q1and q2must have opposite signs and may have different magnitudes

Q: The equation E= kq/r2applies to: A) only pointlike particles B) any symmetric objects C) all objects D) any spherical object E) it applies to all objects as long as they are not moving

Q: An isolated charged point particle produces an electric field with magnitude Eat a point 2 m away. At a point 1 m from the particle the magnitude of the field is: A) E B) 2E C) 4E D) E/2 E) E/4

Q: An isolated point charged point particle produces an electric field with magnitude Eat a point 2 m away from the charge. A point at which the field magnitude is E/4 is: A) 0.5 m away from the charge B) 1 m away from the charge C) 2 m away from the charge D) 4 m away from the charge E) 8 m away from the charge

Q: The electric field at a distance of 10 cm from an isolated point particle with a charge of 2x10-9C is:A) 1.8 N/CB) 18 N/CC) 180 N/CD) 1800 N/CE) none of these

Q: Let kdenote . The magnitude of the electric field at a distance rfrom an isolated point charge qis:A) kq/rB) kr/qC) kq/r3D) kq/r2E) kq2/r2

Q: Two protons (p1and p2) are on the xaxis, as shown below. The directions of the electric field at points 1, 2, and 3 respectively, are: A) , ,  B) , ,  C) , ,  D) , ,  E) , , 

Q: The diagram shows the electric field lines in a region of space containing two small charged spheres (Y and Z). Then: A) Y is negative and Z is positive B) the magnitude of the electric filed is the same everywhere C) the electric field is strongest midway between Y and Z D) Y is positive and Z is negative E) Y and Z must have the same sign

Q: The diagram shows the electric field lines due to two charged parallel metal plates. We conclude that: A) the upper plate is positive and the lower plate is negative B) a proton at X would experience the same force if it were placed at Y C) a proton at X experiences a greater force than if it were placed at Z D) a proton at X experiences less force than if it were placed at Z E) an electron at X could have its weight balanced by the electrical force

Q: Choose the correct statement concerning electric field lines: A) field lines may cross B) field lines are close together where the field is large C) field lines point away from negatively charged particle D) a point charge particle released from rest moves along a field line E) none of these are correct

Q: A certain physics textbook shows a region of space in which two electric field lines cross each other. We conclude that: A) at least two point charges are present B) an electrical conductor is present C) an insulator is present D) the field points in two directions at the same place E) the author made a mistake

Q: Two thin spherical shells, one with radius Rand the other with radius 2R, surround an isolated charge point particle. The ratio of the number of field lines through the larger sphere to the number through the smaller is: A) 1 B) 2 C) 4 D) 1/2 E) 1/4

Q: Electric field lines: A) are trajectories of a test charge B) are vectors in the direction of the electric field C) form closed loops D) cross each other in the region between two point charges E) are none of the above

Q: Experimenter A uses a test charge q0and experimenter B uses a test charge 2q0to measure an electric field produced by stationary charges. A finds a field that is: A) the same as the field found by B B) greater than the field found by B C) less than the field found by B D) either greater or less than the field found by B, depending on the masses of the test charges E) either greater or less than the field found by B, depending on the accelerations of the test charges

Q: As used in the definition of electric field, a "test charge":A) has zero chargeB) must be a protonC) has charge of magnitude 1.6 x10-19CD) must be an electronE) none of the above

Q: An electric field is most directly related to: A) the momentum of a test charge B) the kinetic energy of a test charge C) the potential energy of a test charge D) the force acting on a test charge E) the charge carried by a test charge

Q: The units of the electric field are:A) J/(C.m)B) J/CC) J.CD) J/mE) none of these