Chapter 16: Electric Charge And Electric Field

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Electric Field Quizzes & Trivia

Questions and Answers
  • 1. 

    Is it possible for two negative charges to attract each other?

    • A.

      Yes, they always attract.

    • B.

      Yes, they will attract if they are close enough.

    • C.

      Yes, they will attract if one carries a larger charge than the other.

    • D.

      No, they will never attract.

    Correct Answer
    D. No, they will never attract.
    Explanation
    According to the principles of electrostatics, like charges repel each other, while opposite charges attract. Since both charges in this scenario are negative, they have the same charge and will therefore repel each other, not attract.

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  • 2. 

    Is it possible for a positive and a negative charge to attract each other?

    • A.

      Yes, they always attract.

    • B.

      Yes, they will attract if they are close enough.

    • C.

      Yes, they will attract if one carries a larger charge than the other.

    • D.

      No, they will never attract.

    Correct Answer
    A. Yes, they always attract.
    Explanation
    According to the laws of electromagnetism, positive and negative charges always attract each other. This is because opposite charges have opposite electric fields, and the electric field lines between them attract each other, causing the charges to come together. Therefore, it is possible for a positive and a negative charge to attract each other.

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  • 3. 

    A glass rod is rubbed with a piece of silk. During the process the glass rod acquires a positive charge and the silk

    • A.

      Acquires a positive charge also.

    • B.

      Acquires a negative charge.

    • C.

      Remains neutral.

    • D.

      Could either be positively charged or negatively charged. It depends on how hard the rod was rubbed.

    Correct Answer
    B. Acquires a negative charge.
    Explanation
    When a glass rod is rubbed with a piece of silk, electrons are transferred between the two materials. The glass rod has a higher affinity for electrons, so it pulls electrons from the silk, leaving the silk with a positive charge. The glass rod, on the other hand, gains these electrons and becomes negatively charged. Therefore, the correct answer is that the glass rod acquires a negative charge.

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  • 4. 

    A proton carries a

    • A.

      Positive charge.

    • B.

      Neutral charge.

    • C.

      Negative charge.

    • D.

      Variable charge.

    Correct Answer
    A. Positive charge.
    Explanation
    A proton carries a positive charge because it is one of the fundamental particles that make up an atom's nucleus. It has a charge of +1 elementary charge, which is equal in magnitude but opposite in sign to the electron's charge. This positive charge is what allows protons to attract and bind with negatively charged electrons, forming the structure of an atom.

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  • 5. 

    The model of the atom shows a

    • A.

      Neutrally charged nucleus surrounded by both protons and electrons.

    • B.

      Nucleus consisting of both protons and neutrons, surrounded by a cloud of electrons.

    • C.

      Nucleus consisting of both electrons and neutrons, surrounded by a cloud of protons.

    • D.

      Nucleus consisting of both protons and electrons, surrounded by a cloud of neutrons.

    Correct Answer
    B. Nucleus consisting of both protons and neutrons, surrounded by a cloud of electrons.
    Explanation
    The correct answer is that the model of the atom shows a nucleus consisting of both protons and neutrons, surrounded by a cloud of electrons. This is based on the current understanding of atomic structure, where the nucleus contains the positively charged protons and neutral neutrons, while the negatively charged electrons orbit around the nucleus in energy levels or electron clouds.

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  • 6. 

    A neutral atom always has

    • A.

      More neutrons than protons.

    • B.

      More protons than electrons.

    • C.

      The same number of neutrons as protons.

    • D.

      The same number of protons as electrons.

    Correct Answer
    D. The same number of protons as electrons.
    Explanation
    A neutral atom is one that has an equal number of protons and electrons. Protons have a positive charge, while electrons have a negative charge. The charges of protons and electrons cancel each other out, resulting in a neutral overall charge for the atom. Neutrons, on the other hand, have no charge and do not affect the overall charge of the atom. Therefore, a neutral atom will always have the same number of protons as electrons.

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  • 7. 

    An atom has more electrons than protons. The atom is

    • A.

      A positive ion.

    • B.

      A negative ion.

    • C.

      A superconductor.

    • D.

      Impossible.

    Correct Answer
    B. A negative ion.
    Explanation
    An atom having more electrons than protons indicates that it has gained extra electrons, resulting in a negative charge. This excess of negatively charged electrons makes the atom a negative ion.

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  • 8. 

    Materials in which the electrons are bound very tightly to the nuclei are referred to as

    • A.

      Insulators.

    • B.

      Conductors.

    • C.

      Semiconductors.

    • D.

      Superconductors.

    Correct Answer
    A. Insulators.
    Explanation
    Insulators are materials in which the electrons are tightly bound to the nuclei, meaning they are not free to move easily. This lack of mobility prevents the flow of electric current through the material. Conductors, on the other hand, have loosely bound electrons that can move freely, allowing for the easy flow of electric current. Semiconductors have properties that lie between those of insulators and conductors, while superconductors are materials that exhibit zero electrical resistance at very low temperatures. Therefore, the correct answer is insulators.

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  • 9. 

    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.

      Conductors.

    • C.

      Semiconductors.

    • D.

      Superconductors.

    Correct Answer
    B. Conductors.
    Explanation
    Conductors are materials in which electrons are bound very loosely to the nuclei and can move about freely within the material. This allows for the easy flow of electric current through the material. Insulators, on the other hand, have tightly bound electrons that do not move easily, while semiconductors have properties in between conductors and insulators. Superconductors are materials that exhibit zero electrical resistance at very low temperatures.

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  • 10. 

    A negatively charged rod is brought near one end of an uncharged metal bar. The end of the metal bar farthest from the charged rod will be charged

    • A.

      Positive.

    • B.

      Negative.

    • C.

      Neutral.

    • D.

      None of the given answers

    Correct Answer
    B. Negative.
    Explanation
    When a negatively charged rod is brought near one end of an uncharged metal bar, the negative charges in the metal bar will be repelled by the negative charges on the rod. This will cause the positive charges in the metal bar to move towards the end closest to the rod, leaving the end farthest from the rod with an excess of negative charges. Therefore, the end of the metal bar farthest from the charged rod will be charged negative.

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  • 11. 

    Sphere A carries a net positive charge, and sphere B is neutral. They are placed near each other on an insulated table. Sphere B is briefly touched with a wire that is grounded. Which statement is correct?

    • A.

      Sphere B remains neutral.

    • B.

      Sphere B is now positively charged.

    • C.

      Sphere B is now negatively charged.

    • D.

      The charge on sphere B cannot be determined without additional information.

    Correct Answer
    C. Sphere B is now negatively charged.
    Explanation
    When sphere B is briefly touched with a wire that is grounded, it means that any excess charge on sphere B is transferred to the ground. Since sphere A carries a net positive charge, when sphere B is touched, it will gain electrons from the ground, resulting in an excess of electrons on sphere B. This means that sphere B is now negatively charged.

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  • 12. 

    How can a negatively charged rod charge an electroscope positively?

    • A.

      By conduction

    • B.

      By induction

    • C.

      By deduction

    • D.

      It cannot.

    Correct Answer
    B. By induction
    Explanation
    A negatively charged rod can charge an electroscope positively by induction. When the negatively charged rod is brought close to the electroscope, the negative charges in the rod repel the electrons in the electroscope, causing them to move away from the rod. This leaves a net positive charge on the electroscope.

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  • 13. 

    An originally neutral electroscope is briefly touched with a positively charged glass rod. The electroscope

    • A.

      Remains neutral.

    • B.

      Becomes negatively charged.

    • C.

      Becomes positively charged.

    • D.

      Could become either positively or negatively charged, depending on the time of contact.

    Correct Answer
    C. Becomes positively charged.
    Explanation
    When a positively charged glass rod is briefly touched with a neutral electroscope, some of the positive charge from the rod is transferred to the electroscope. This causes an imbalance of charges in the electroscope, resulting in an overall positive charge. Therefore, the electroscope becomes positively charged.

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  • 14. 

    An originally neutral electroscope is grounded briefly while a positively charged glass rod is held near it. After the glass rod is removed, the electroscope

    • A.

      Remains neutral.

    • B.

      Is negatively charged.

    • C.

      Is positively charged.

    • D.

      Could be either positively or negatively charged, depending on how long the contact with ground lasted.

    Correct Answer
    B. Is negatively charged.
    Explanation
    When the originally neutral electroscope is grounded, any excess charge is transferred to the ground, leaving the electroscope neutral. When the positively charged glass rod is brought near the electroscope, it induces a negative charge on the electroscope by repelling the electrons in the electroscope. However, once the glass rod is removed, the electroscope remains negatively charged because the excess electrons are not able to escape to the ground. Therefore, the correct answer is that the electroscope is negatively charged.

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  • 15. 

    A positive object touches a neutral electroscope, and the leaves separate. Then a negative object is brought near the electroscope, but does not touch it. What happens to the leaves?

    • A.

      They separate further.

    • B.

      They move closer together.

    • C.

      They are unaffected.

    • D.

      Cannot be determined without further information

    Correct Answer
    B. They move closer together.
    Explanation
    When a positive object touches a neutral electroscope, the leaves separate because the positive charge is transferred to the electroscope, causing the leaves to repel each other. However, when a negative object is brought near the electroscope, the negative charge induces a positive charge on the leaves, attracting them towards the negative object. This attraction causes the leaves to move closer together. Therefore, the correct answer is that the leaves move closer together when a negative object is brought near the electroscope without touching it.

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  • 16. 

    A large negatively charged object is placed on an insulated table. A neutral metallic ball rolls straight toward the object, but stops before it touches it. A second neutral metallic ball rolls along the path followed by the first ball, strikes the first ball, and stops. The first ball rolls forward, but does not touch the negative object. At no time does either ball touch the negative object. What is the final charge on each ball?

    • A.

      The first ball is positive, and the second ball is negative.

    • B.

      The first ball is negative, and the second ball is positive.

    • C.

      Both balls remain neutral.

    • D.

      Both balls are positive.

    Correct Answer
    A. The first ball is positive, and the second ball is negative.
    Explanation
    When the first neutral metallic ball rolls towards the negatively charged object, it gets polarized. This means that the negative charges in the object repel the electrons in the ball, causing them to move to the far side of the ball, leaving the near side positively charged. This positive charge on the first ball repels the electrons in the second neutral metallic ball, causing them to move to the far side of the second ball, leaving the near side negatively charged. When the second ball strikes the first ball, the opposite charges attract each other, causing the transfer of electrons. As a result, the first ball becomes positively charged and the second ball becomes negatively charged.

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  • 17. 

    Charge is

    • A.

      Quantized.

    • B.

      Conserved.

    • C.

      Invariant.

    • D.

      All of the given answers

    Correct Answer
    D. All of the given answers
    Explanation
    The correct answer is "all of the given answers." This means that charge is both quantized, meaning it exists in discrete units, and conserved, meaning it cannot be created or destroyed but can only be transferred or redistributed. Additionally, charge is invariant, meaning it remains constant in certain physical processes. Therefore, all of these statements accurately describe the nature of charge.

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  • 18. 

    What are the units of the Coulomb constant k, which appears in Coulomb's law?

    • A.

      N*m/C

    • B.

      N/C

    • C.

      N^2*m/C^2

    • D.

      N*m^2/C^2

    Correct Answer
    D. N*m^2/C^2
    Explanation
    The Coulomb constant, k, is a proportionality constant that appears in Coulomb's law, which relates the force between two charged objects. The units of k can be determined by examining the units in Coulomb's law equation. The equation states that the force (F) between two charges (q1 and q2) is equal to the Coulomb constant (k) multiplied by the product of the charges (q1*q2) and divided by the square of the distance between them (r^2). By rearranging the equation, we can determine the units of k to be N*m^2/C^2, where N represents Newtons (the unit of force), m represents meters (the unit of distance), and C represents Coulombs (the unit of charge).

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  • 19. 

    Two charged objects are separated by a distance d. The first charge is larger in magnitude than the second charge.

    • A.

      The first charge exerts a larger force on the second charge.

    • B.

      The second charge exerts a larger force on the first charge.

    • C.

      The charges exert forces on each other equal in magnitude and opposite in direction.

    • D.

      The charges exert forces on each other equal in magnitude and pointing in the same direction.

    Correct Answer
    C. The charges exert forces on each other equal in magnitude and opposite in direction.
    Explanation
    The charges exert forces on each other equal in magnitude and opposite in direction because according to Coulomb's law, the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Since the first charge is larger in magnitude, it will exert a larger force on the second charge. However, the second charge will also exert a force on the first charge, but in the opposite direction, resulting in forces that are equal in magnitude and opposite in direction.

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  • 20. 

    Sphere A carries a net charge and sphere B is neutral. They are placed near each other on an insulated table. Which statement best describes the electrostatic force between them?

    • A.

      There is no force between them since one is neutral.

    • B.

      There is a force of repulsion between them.

    • C.

      There is a force of attraction between them.

    • D.

      The force is attractive if A is charged positively and repulsive if A is charged

    Correct Answer
    C. There is a force of attraction between them.
    Explanation
    The statement "There is a force of attraction between them" is the best description of the electrostatic force between sphere A and sphere B. This is because sphere A carries a net charge, which creates an electric field around it. This electric field interacts with the neutral sphere B, causing an attraction between the two spheres. The force of attraction is a fundamental property of electric charges, where opposite charges attract each other.

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  • 21. 

    Two charged objects attract each other with a certain force. If the charges on both objects are doubled with no change in separation, the force between them

    • A.

      Quadruples.

    • B.

      Doubles.

    • C.

      Halves.

    • D.

      Increases, but we can't say how much without knowing the distance between them.

    Correct Answer
    A. Quadruples.
    Explanation
    When the charges on both objects are doubled, the force between them is directly proportional to the product of the charges. Since both charges are doubled, the product of the charges is quadrupled. Therefore, the force between them also quadruples.

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  • 22. 

    Two charges are separated by a distance d and exert mutual attractive forces of F on each other. If the charges are separated by a distance of d/3, what are the new mutual forces?

    • A.

      F/9

    • B.

      F/3

    • C.

      3F

    • D.

      9F

    Correct Answer
    D. 9F
    Explanation
    When the charges are separated by a distance of d/3, the new mutual forces between them will be 9 times stronger than before. This is because the force between two charges is inversely proportional to the square of the distance between them. As the distance decreases to 1/3 of its original value, the force increases by a factor of (1/(1/3))^2 = 9. Therefore, the new mutual forces will be 9F.

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  • 23. 

    Two charged objects attract each other with a force F. What happens to the force between them if one charge is doubled, the other charge is tripled, and the separation distance between their centers is reduced to one-fourth its original value? The force is now equal to

    • A.

      16F.

    • B.

      24F.

    • C.

      (3/8)F.

    • D.

      96F.

    Correct Answer
    D. 96F.
    Explanation
    When one charge is doubled, the force between the two charges increases by a factor of 2. When the other charge is tripled, the force between the two charges increases by a factor of 3. When the separation distance is reduced to one-fourth its original value, the force between the two charges increases by a factor of 16 (since force is inversely proportional to the square of the distance). Therefore, the final force is equal to the product of these factors: 2 x 3 x 16 = 96. Hence, the force is now equal to 96F.

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  • 24. 

    An electron and a proton are separated by a distance of 1.0 m. What happens to the magnitude of the force on the proton if a second electron is placed next to the first electron?

    • A.

      It quadruples.

    • B.

      It doubles.

    • C.

      It will not change.

    • D.

      It goes to zero.

    Correct Answer
    B. It doubles.
    Explanation
    When a second electron is placed next to the first electron, both electrons have the same charge, which is negative. Since like charges repel each other, the second electron will exert a repulsive force on the first electron. According to Newton's third law of motion, the first electron will also exert an equal and opposite force on the second electron. However, the question asks about the magnitude of the force on the proton, not the second electron. Since the proton has a positive charge, it will experience an attractive force towards the second electron. Therefore, the magnitude of the force on the proton doubles.

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  • 25. 

    An electron and a proton are separated by a distance of 1.0 m. What happens to the magnitude of the force on the first electron if a second electron is placed next to the proton?

    • A.

      It doubles.

    • B.

      It does not change.

    • C.

      It is reduced to half.

    • D.

      It becomes zero.

    Correct Answer
    D. It becomes zero.
    Explanation
    When a second electron is placed next to the proton, it creates a repulsive force between the two electrons. This repulsive force cancels out the attractive force between the electron and the proton. As a result, the net force on the first electron becomes zero, causing the magnitude of the force to become zero.

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  • 26. 

    An electron and a proton are separated by a distance of 1.0 m. What happens to the size of the force on the proton if the electron is moved 0.50 m closer to the proton?

    • A.

      It increases to 4 times its original value.

    • B.

      It increases to 2 times its original value.

    • C.

      It decreases to one-half its original value.

    • D.

      It decreases to one-fourth its original value.

    Correct Answer
    A. It increases to 4 times its original value.
    Explanation
    When the electron is moved 0.50 m closer to the proton, the distance between them decreases by half. According to Coulomb's law, the force between two charges is inversely proportional to the square of the distance between them. Therefore, when the distance is halved, the force increases by a factor of (1/0.5)^2 = 4. Hence, the size of the force on the proton increases to 4 times its original value.

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  • 27. 

    A point charge of +Q is placed at the center of a square. When a second point charge of -Q is placed at one of the square's corners, it is observed that an electrostatic force of 2.0 N acts on the positive charge at the square's center. Now, identical charges of -Q are placed at the other three corners of the square. What is the magnitude of the net electrostatic force acting on the positive charge at the center of the square?

    • A.

      Zero

    • B.

      2.8 N

    • C.

      4.0 N

    • D.

      8.0 N

    Correct Answer
    A. Zero
    Explanation
    When a second point charge of -Q is placed at one corner of the square, the electrostatic force between the two charges is attractive and has a magnitude of 2.0 N. However, when identical charges of -Q are placed at the other three corners of the square, the forces between the positive charge at the center and each of the negative charges cancel out. This is because the forces are equal in magnitude and opposite in direction, resulting in a net force of zero. Therefore, the magnitude of the net electrostatic force acting on the positive charge at the center of the square is zero.

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  • 28. 

    Which of the following is not a vector?

    • A.

      Electric force

    • B.

      Electric field

    • C.

      Electric charge

    • D.

      Electric line of force

    Correct Answer
    C. Electric charge
    Explanation
    Electric charge is not a vector because it does not have both magnitude and direction. Unlike electric force, electric field, and electric line of force, electric charge is a scalar quantity that only has magnitude.

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  • 29. 

    At twice the distance from a point charge, the strength of the electric field

    • A.

      Is four times its original value.

    • B.

      Is twice its original value.

    • C.

      Is one-half its original value.

    • D.

      Is one-fourth its original value.

    Correct Answer
    D. Is one-fourth its original value.
    Explanation
    The strength of the electric field is inversely proportional to the square of the distance from the point charge. This means that as the distance from the point charge doubles, the strength of the electric field decreases by a factor of four. Therefore, at twice the distance, the strength of the electric field is one-fourth of its original value.

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  • 30. 

    Is it possible to have a zero electric field value between a negative and positive charge along the line joining the two charges?

    • A.

      Yes, if the two charges are equal in magnitude.

    • B.

      Yes, regardless of the magnitude of the two charges.

    • C.

      No, a zero electric field cannot exist between the two charges.

    • D.

      Cannot be determined without knowing the separation between the two charges

    Correct Answer
    C. No, a zero electric field cannot exist between the two charges.
    Explanation
    When there is a negative and positive charge along the line joining them, the electric field created by the negative charge points towards it, while the electric field created by the positive charge points away from it. These two electric fields add up to form a net electric field between the charges. Since the electric fields are in opposite directions, they cannot cancel each other out completely, meaning that a zero electric field cannot exist between the charges.

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  • 31. 

    Is it possible to have a zero electric field value between two positive charges along the line joining the two charges?

    • A.

      Yes, if the two charges are equal in magnitude.

    • B.

      Yes, regardless of the magnitude of the two charges.

    • C.

      No, a zero electric field cannot exist between the two charges.

    • D.

      Annot be determined without knowing the separation between the two charges

    Correct Answer
    B. Yes, regardless of the magnitude of the two charges.
    Explanation
    It is possible to have a zero electric field value between two positive charges along the line joining the two charges, regardless of the magnitude of the charges. This is because the electric field due to each charge is directed away from the charge, and if the magnitudes of the two charges are equal, the electric fields cancel each other out at a specific point between the charges. This results in a net electric field of zero at that point.

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  • 32. 

    Electric field lines near psitive point charges

    • A.

      Circle clockwise.

    • B.

      Circle counter-clockwise.

    • C.

      Radiate inward.

    • D.

      Radiate outward.

    Correct Answer
    D. Radiate outward.
    Explanation
    The correct answer is "radiate outward." This is because electric field lines always point away from positive charges. In the case of positive point charges, the electric field lines extend outward in all directions, indicating the direction in which a positive test charge would move if placed in the field.

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  • 33. 

    Can electric field lines intersect in free space?

    • A.

      Yes, but only at the midpoint between two equal like charges.

    • B.

      Yes, but only at the midpoint between a positive and a negative charge.

    • C.

      Yes, but only at the centroid of an equilateral triangle with like charges at each corner.

    • D.

      No.

    Correct Answer
    D. No.
    Explanation
    Electric field lines represent the direction and magnitude of the electric field at any given point in space. If the electric field lines were to intersect, it would mean that at that point, there are two different directions and magnitudes of the electric field, which is not possible. Electric field lines never intersect in free space.

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  • 34. 

    A solid block of metal in electrostatic equilibrium is placed in a uniform electric field. Give a statement concerning the electric field in the block's interior.

    • A.

      The interior field points in a direction opposite to the exterior field.

    • B.

      The interior field points in a direction that is at right angles to the exterior field.

    • C.

      The interior points in a direction that is parallel to the exterior field.

    • D.

      There is no electric field in the block's interior.

    Correct Answer
    D. There is no electric field in the block's interior.
    Explanation
    In electrostatic equilibrium, the charges inside a solid block of metal redistribute themselves in such a way that the electric field inside the block becomes zero. This is because the charges move freely within the metal and redistribute themselves until they cancel out the external electric field. Therefore, there is no electric field in the block's interior.

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  • 35. 

    If a solid metal sphere and a hollow metal sphere of equal diameters are each given the same charge, the electric field (E) midway between the center and the surface is

    • A.

      Greater for the solid sphere than for the hollow sphere.

    • B.

      Greater for the hollow sphere than for the solid sphere.

    • C.

      Zero for both.

    • D.

      Equal in magnitude for both, but one is opposite in direction from the other.

    Correct Answer
    C. Zero for both.
    Explanation
    The electric field midway between the center and the surface of both the solid and hollow metal spheres is zero. This is because the charge on the spheres is uniformly distributed, and at this point, the electric field contributions from all points on the sphere cancel each other out. Therefore, the electric field is zero for both spheres.

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  • 36. 

    A cubic block of aluminum rests on a wooden table in a region where a uniform electric field is directed straight upward. What can be said concerning the charge on the block's top surface?

    • A.

      The top surface is charged positively.

    • B.

      The top surface is charged negatively.

    • C.

      The top surface is neutral.

    • D.

      The top surface's charge cannot be determined without further information.

    Correct Answer
    A. The top surface is charged positively.
    Explanation
    The top surface of the aluminum block is charged positively because the uniform electric field is directed straight upward. In a uniform electric field, positive charges will be attracted towards the direction of the field and negative charges will be repelled. Since the top surface of the block is attracted towards the field, it must be positively charged.

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  • 37. 

    If a conductor is in electrostatic equilibrium near an electric charge

    • A.

      The total charge on the conductor must be zero.

    • B.

      The force between the conductor and the charge must be zero.

    • C.

      The total electric field of the conductor must be zero.

    • D.

      The electric field on the surface of the conductor is perpendicular to the surface.

    Correct Answer
    D. The electric field on the surface of the conductor is perpendicular to the surface.
    Explanation
    In electrostatic equilibrium, the charges on the conductor redistribute themselves in such a way that the electric field inside the conductor is zero. This means that the electric field on the surface of the conductor must also be zero, as any non-zero electric field on the surface would cause the charges to move. Therefore, the electric field on the surface of the conductor is perpendicular to the surface.

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  • 38. 

    A positive point charge is enclosed in a hollow metallic sphere that is grounded. As compared to the case without the hollow sphere, the electric field at a point directly above the hollow sphere has

    • A.

      Diminished to zero.

    • B.

      Diminished somewhat.

    • C.

      Increased somewhat.

    • D.

      Not changed.

    Correct Answer
    A. Diminished to zero.
    Explanation
    When a positive point charge is enclosed in a hollow metallic sphere that is grounded, the electric field inside the hollow sphere becomes zero. This is because the charges in the metallic sphere redistribute themselves in such a way that the electric field inside the sphere cancels out the electric field of the point charge. As a result, the electric field at a point directly above the hollow sphere, which is outside the sphere, diminishes to zero.

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  • 39. 

    The charge carried by one electron is e = -1.6 * 10^(-19) C. The number of electrons necessary to produce a charge of -1.0 C is

    • A.

      6.25 * 10^18.

    • B.

      6.25 * 10^9.

    • C.

      1.6 * 10^19.

    • D.

      None of the given answers

    Correct Answer
    A. 6.25 * 10^18.
    Explanation
    The charge carried by one electron is -1.6 * 10^(-19) C. To find the number of electrons necessary to produce a charge of -1.0 C, we can divide the total charge by the charge carried by one electron. Therefore, -1.0 C / (-1.6 * 10^(-19) C) = 6.25 * 10^18 electrons. Hence, the correct answer is 6.25 * 10^18.

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  • 40. 

    A piece of plastic has a net charge of +2.00 μC. How many more protons than electrons does this piece of plastic have?

    • A.

      1.25 * 10^13

    • B.

      1.25 * 10^19

    • C.

      2.50 * 10^13

    • D.

      2.50 * 10^19

    Correct Answer
    A. 1.25 * 10^13
    Explanation
    The net charge of +2.00 μC indicates that the piece of plastic has an excess of 2.00 μC worth of positive charge. Since protons carry a positive charge and electrons carry a negative charge, the piece of plastic must have 2.00 μC worth of extra protons compared to electrons. Therefore, the piece of plastic has 1.25 * 10^13 more protons than electrons.

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  • 41. 

    What is the charge on 1 kg of protons?

    • A.

      1.0 C

    • B.

      1000 C

    • C.

      9.6 * 10^7 C

    • D.

      6.0 * 10^26 C

    Correct Answer
    C. 9.6 * 10^7 C
    Explanation
    The charge on 1 kg of protons is 9.6 * 10^7 C. This is because the charge of a proton is 1.6 * 10^-19 C, and there are approximately 6.02 * 10^23 protons in 1 kg. Therefore, the total charge on 1 kg of protons can be calculated by multiplying the charge of a single proton by the number of protons, resulting in 9.6 * 10^7 C.

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  • 42. 

    An atomic nucleus has a charge of +40e. An electron is 10^(-9) m from the nucleus. What is the force on the electron?

    • A.

      2.9 nN

    • B.

      1000 C

    • C.

      3.7 nN

    • D.

      6.8 nN

    • E.

      9.2 nN

    Correct Answer
    E. 9.2 nN
    Explanation
    The force on an electron due to the electric field created by a charged nucleus can be calculated using Coulomb's law. Coulomb's law states that the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. In this case, the charge of the nucleus is +40e and the distance between the electron and the nucleus is 10^(-9) m. Therefore, the force on the electron can be calculated as (40e * e)/(4πε₀ * (10^(-9))^2), where e is the elementary charge and ε₀ is the permittivity of free space. This calculation gives a force of approximately 9.2 nN.

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  • 43. 

    Two point charges, separated by 1.5 cm, have charge values of 2.0 and -4.0 μC, respectively. What is the magnitude of the electric force between them?

    • A.

      400 N

    • B.

      360 N

    • C.

      320 N

    • D.

      160 N

    Correct Answer
    C. 320 N
    Explanation
    The magnitude of the electric force between two point charges can be calculated using Coulomb's Law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. In this case, the charges are 2.0 and -4.0 μC, and the distance between them is 1.5 cm. Plugging these values into the equation, we can calculate the magnitude of the electric force to be 320 N.

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  • 44. 

    A 1.0-C charge is 15 m from a second charge, and the force between them is 1.0 N. What is the magnitude of the second charge?

    • A.

      25 C

    • B.

      1.0 C

    • C.

      0.025 C

    • D.

      25 nC

    Correct Answer
    D. 25 nC
    Explanation
    The force between two charges is given by Coulomb's Law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. In this case, we are given the force, the distance, and one of the charges. By rearranging the equation and substituting the known values, we can solve for the magnitude of the second charge.

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  • 45. 

    Two 1.0-C charges have a force between them of 1.0 N. How far apart are they?

    • A.

      95 km

    • B.

      9.5 m

    • C.

      4.0 m

    • D.

      4.0 mm

    Correct Answer
    A. 95 km
    Explanation
    The given answer of 95 km is incorrect. The force between two charges is given by Coulomb's law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. In this case, the force is 1.0 N, which means the charges are relatively small. Therefore, it is unlikely that they would be 95 km apart. A more reasonable distance would be in the order of meters or millimeters.

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  • 46. 

    The force between a 30-μC charge and a -90-mC charge is 1.8 N. How far apart are they?

    • A.

      1.9 m

    • B.

      2.3 m

    • C.

      3.7 m

    • D.

      4.2 m

    Correct Answer
    C. 3.7 m
    Explanation
    The force between two charges is given by Coulomb's law, which states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. In this case, the force is given as 1.8 N. By rearranging Coulomb's law and plugging in the given charges, we can solve for the distance between the charges. The correct answer of 3.7 m indicates that the charges are 3.7 meters apart.

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  • 47. 

    Two point charges, initially 2.0 cm apart, experience a 1.0-N force. If they are moved to a new separation of 8.0 cm, what is the electric force between them?

    • A.

      4.0 N

    • B.

      16 N

    • C.

      1/4 N

    • D.

      1/16 N

    Correct Answer
    D. 1/16 N
    Explanation
    When the two point charges are initially 2.0 cm apart, they experience a 1.0-N force. If they are moved to a new separation of 8.0 cm, the electric force between them can be calculated using Coulomb's law. Coulomb's law states that the electric force between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Since the distance is increased by a factor of 4 (from 2.0 cm to 8.0 cm), the electric force will decrease by a factor of 16. Therefore, the electric force between them is 1/16 N.

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  • 48. 

    Three identical point charges of 2.0 μC are placed on the x-axis. The first charge is at the origin, the second to the right at x = 50 cm, and the third is at the 100 cm mark. What are the magnitude and direction of the electrostatic force which acts on the charge at the origin?

    • A.

      0.18 N left

    • B.

      0.18 N right

    • C.

      0.36 N left

    • D.

      0.36 N right

    Correct Answer
    A. 0.18 N left
    Explanation
    The magnitude of the electrostatic force can be calculated using Coulomb's law, which states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. In this case, the charge at the origin is being acted upon by the charges at x = 50 cm and 100 cm. Since all three charges are identical, the forces exerted by the charges at x = 50 cm and 100 cm will be equal in magnitude but opposite in direction. Therefore, the net force on the charge at the origin will be the sum of these two forces. As a result, the magnitude of the net force will be 0.18 N and it will be directed to the left.

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  • 49. 

    Three point charges are placed on the x-axis. A charge of +2.0 μC is placed at the origin, -2.0 μC to the right at x = 50 cm, and +4.0 μC at the 100 cm mark. What are the magnitude and direction of the electrostatic force which acts on the charge at the origin?

    • A.

      0.072 N right

    • B.

      0.072 N left

    • C.

      0.14 N right

    • D.

      0.14 N left

    Correct Answer
    A. 0.072 N right
    Explanation
    The magnitude of the electrostatic force can be calculated using Coulomb's law, which states that the force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them. In this case, the charge at the origin (2.0 μC) and the charge at x = 50 cm (-2.0 μC) are attracting each other, so the force is directed to the right. The magnitude of the force can be calculated as F = k * (q1 * q2) / r^2, where k is the electrostatic constant, q1 and q2 are the magnitudes of the charges, and r is the distance between them. Plugging in the values, we get F = (9 * 10^9 N * m^2 / C^2) * ((2.0 * 10^-6 C) * (-2.0 * 10^-6 C)) / (0.5 m)^2 = 0.072 N. Therefore, the magnitude of the electrostatic force acting on the charge at the origin is 0.072 N, and it is directed to the right.

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  • 50. 

    Three point charges are located at the following positions: Q1 = 2.00 μC at x = 1.00 m; Q2 = 3.00 μC at x = 0; Q3 = -5.00 μC at x = -1.00 m. What is the magnitude of the force on the 3.00-mC charge?

    • A.

      5.40 * 10^(-2) N

    • B.

      0.135 N

    • C.

      8.10 * 10^(-2) N

    • D.

      0.189 N

    Correct Answer
    D. 0.189 N
    Explanation
    The magnitude of the force on the 3.00-mC charge can be calculated using Coulomb's Law. Coulomb's Law states that the force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them. In this case, the force on the 3.00-mC charge is determined by the interaction with the other charges Q1 and Q3. By applying Coulomb's Law and considering the distances between the charges, the magnitude of the force is found to be 0.189 N.

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  • Mar 21, 2023
    Quiz Edited by
    ProProfs Editorial Team
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    Drtaylor
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