Equipotential Lines Quiz
The question sheet
Reveal any answer as you study-
In two dimensions, lines representing places where the electric potential is constant are called what?
- Electric field lines
- Equipotential lines
- Voltage arrows
- Charge lines
Reveal answer
Answer: Equipotential lines
Source evidence
PDF page 907: We can represent electric potentials (voltages) pictorially, just as we drew pictures to illustrate electric fields. Of course, the two are related. Consider Figure 19.8, which shows an isolated positive point charge and its electric field lines. Electric field lines radiate out from a positive charge and terminate on negative charges. While we use blue arrows to represent the magnitude and direction of the electric field, we use green lines to represent places where the electric potential is constant. These are called equipotential lines in two dimensions, or equipotential surfaces in three dimensions. The term equipotential is also used as a noun, referring to an equipotential line or surface. The potential for a point charge is the same anywhere on an imaginary sphere of radius surrounding the charge. This is true since the potential for a point charge is given by and, thus, has the same value at any point that is a given distance from the charge. An equipotential sphere is a circle in the two-dimensional view of Figure 19.8. Since the electric field lines point radially away from the charge, they are perpendicular to the equipotential lines.
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How are equipotential lines oriented relative to electric field lines?
- At 45 degrees
- Perpendicular
- Parallel
- Randomly
Reveal answer
Answer: Perpendicular
Source evidence
PDF page 907: We can represent electric potentials (voltages) pictorially, just as we drew pictures to illustrate electric fields. Of course, the two are related. Consider Figure 19.8, which shows an isolated positive point charge and its electric field lines. Electric field lines radiate out from a positive charge and terminate on negative charges. While we use blue arrows to represent the magnitude and direction of the electric field, we use green lines to represent places where the electric potential is constant. These are called equipotential lines in two dimensions, or equipotential surfaces in three dimensions. The term equipotential is also used as a noun, referring to an equipotential line or surface. The potential for a point charge is the same anywhere on an imaginary sphere of radius surrounding the charge. This is true since the potential for a point charge is given by and, thus, has the same value at any point that is a given distance from the charge. An equipotential sphere is a circle in the two-dimensional view of Figure 19.8. Since the electric field lines point radially away from the charge, they are perpendicular to the equipotential lines.
PDF page 907: each equipotential line, meaning that no work is required to move a charge anywhere along one of those lines. Work is needed to move a charge from one equipotential line to another. Equipotential lines are perpendicular to electric field lines in every case. It is important to note that equipotential lines are always perpendicular to electric field lines. No work is required to move a charge along an equipotential, since . Thus the work is
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How much work is required to move a charge along an equipotential line?
- Maximum work
- Depends on charge
- No work
- Half the work
Reveal answer
Answer: No work
Source evidence
PDF page 907: each equipotential line, meaning that no work is required to move a charge anywhere along one of those lines. Work is needed to move a charge from one equipotential line to another. Equipotential lines are perpendicular to electric field lines in every case. It is important to note that equipotential lines are always perpendicular to electric field lines. No work is required to move a charge along an equipotential, since . Thus the work is
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For an isolated positive point charge, an equipotential surface has what shape?
- A cube
- A cone
- A flat plane
- A sphere
Reveal answer
Answer: A sphere
Source evidence
PDF page 907: We can represent electric potentials (voltages) pictorially, just as we drew pictures to illustrate electric fields. Of course, the two are related. Consider Figure 19.8, which shows an isolated positive point charge and its electric field lines. Electric field lines radiate out from a positive charge and terminate on negative charges. While we use blue arrows to represent the magnitude and direction of the electric field, we use green lines to represent places where the electric potential is constant. These are called equipotential lines in two dimensions, or equipotential surfaces in three dimensions. The term equipotential is also used as a noun, referring to an equipotential line or surface. The potential for a point charge is the same anywhere on an imaginary sphere of radius surrounding the charge. This is true since the potential for a point charge is given by and, thus, has the same value at any point that is a given distance from the charge. An equipotential sphere is a circle in the two-dimensional view of Figure 19.8. Since the electric field lines point radially away from the charge, they are perpendicular to the equipotential lines.
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Electric field lines from a positive charge point in which direction relative to the charge?
- Circularly
- Radially inward
- Tangentially
- Radially outward
Reveal answer
Answer: Radially outward
Source evidence
PDF page 907: We can represent electric potentials (voltages) pictorially, just as we drew pictures to illustrate electric fields. Of course, the two are related. Consider Figure 19.8, which shows an isolated positive point charge and its electric field lines. Electric field lines radiate out from a positive charge and terminate on negative charges. While we use blue arrows to represent the magnitude and direction of the electric field, we use green lines to represent places where the electric potential is constant. These are called equipotential lines in two dimensions, or equipotential surfaces in three dimensions. The term equipotential is also used as a noun, referring to an equipotential line or surface. The potential for a point charge is the same anywhere on an imaginary sphere of radius surrounding the charge. This is true since the potential for a point charge is given by and, thus, has the same value at any point that is a given distance from the charge. An equipotential sphere is a circle in the two-dimensional view of Figure 19.8. Since the electric field lines point radially away from the charge, they are perpendicular to the equipotential lines.
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Why is the potential the same anywhere on a sphere around a point charge?
- There is no field
- The charge is zero
- Potential depends only on distance
- Field lines are curved
Reveal answer
Answer: Potential depends only on distance
Source evidence
PDF page 907: We can represent electric potentials (voltages) pictorially, just as we drew pictures to illustrate electric fields. Of course, the two are related. Consider Figure 19.8, which shows an isolated positive point charge and its electric field lines. Electric field lines radiate out from a positive charge and terminate on negative charges. While we use blue arrows to represent the magnitude and direction of the electric field, we use green lines to represent places where the electric potential is constant. These are called equipotential lines in two dimensions, or equipotential surfaces in three dimensions. The term equipotential is also used as a noun, referring to an equipotential line or surface. The potential for a point charge is the same anywhere on an imaginary sphere of radius surrounding the charge. This is true since the potential for a point charge is given by and, thus, has the same value at any point that is a given distance from the charge. An equipotential sphere is a circle in the two-dimensional view of Figure 19.8. Since the electric field lines point radially away from the charge, they are perpendicular to the equipotential lines.
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Connecting a conductor to the earth with a good conductor is called what?
- Polarizing
- Insulating
- Grounding
- Charging
Reveal answer
Answer: Grounding
Source evidence
PDF page 908: respectively. Neither nor nor is zero, and so must be 0, meaning must be . In other words, motion along an equipotential is perpendicular to . One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is an equipotential surface in static situations. There can be no voltage difference across the surface of a conductor, or charges will flow. One of the uses of this fact is that a conductor can be fixed at zero volts by connecting it to the earth with a good conductor—a process called grounding. Grounding can be a useful safety tool. For example, grounding the metal case of an electrical appliance ensures that it is at zero volts relative to the earth.
PDF page 908: A conductor can be fixed at zero volts by connecting it to the earth with a good conductor—a process called grounding.
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Grounding the metal case of an electrical appliance ensures it is at what voltage relative to earth?
- Zero volts
- 12 volts
- Negative volts
- Maximum volts
Reveal answer
Answer: Zero volts
Source evidence
PDF page 908: respectively. Neither nor nor is zero, and so must be 0, meaning must be . In other words, motion along an equipotential is perpendicular to . One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is an equipotential surface in static situations. There can be no voltage difference across the surface of a conductor, or charges will flow. One of the uses of this fact is that a conductor can be fixed at zero volts by connecting it to the earth with a good conductor—a process called grounding. Grounding can be a useful safety tool. For example, grounding the metal case of an electrical appliance ensures that it is at zero volts relative to the earth.
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In static situations, a conductor's surface is described as what kind of surface?
- A charged plane
- An equipotential surface
- An insulator
- A field source
Reveal answer
Answer: An equipotential surface
Source evidence
PDF page 908: respectively. Neither nor nor is zero, and so must be 0, meaning must be . In other words, motion along an equipotential is perpendicular to . One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is an equipotential surface in static situations. There can be no voltage difference across the surface of a conductor, or charges will flow. One of the uses of this fact is that a conductor can be fixed at zero volts by connecting it to the earth with a good conductor—a process called grounding. Grounding can be a useful safety tool. For example, grounding the metal case of an electrical appliance ensures that it is at zero volts relative to the earth.
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Why can there be no voltage difference across a conductor's surface in static situations?
- Charges would flow
- It has no charge
- It is insulated
- Field is parallel
Reveal answer
Answer: Charges would flow
Source evidence
PDF page 908: respectively. Neither nor nor is zero, and so must be 0, meaning must be . In other words, motion along an equipotential is perpendicular to . One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is an equipotential surface in static situations. There can be no voltage difference across the surface of a conductor, or charges will flow. One of the uses of this fact is that a conductor can be fixed at zero volts by connecting it to the earth with a good conductor—a process called grounding. Grounding can be a useful safety tool. For example, grounding the metal case of an electrical appliance ensures that it is at zero volts relative to the earth.
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The electric field must be oriented how relative to the surface of any conductor?
- Perpendicular to it
- At 30 degrees
- Along the surface
- Parallel to it
Reveal answer
Answer: Perpendicular to it
Source evidence
PDF page 908: respectively. Neither nor nor is zero, and so must be 0, meaning must be . In other words, motion along an equipotential is perpendicular to . One of the rules for static electric fields and conductors is that the electric field must be perpendicular to the surface of any conductor. This implies that a conductor is an equipotential surface in static situations. There can be no voltage difference across the surface of a conductor, or charges will flow. One of the uses of this fact is that a conductor can be fixed at zero volts by connecting it to the earth with a good conductor—a process called grounding. Grounding can be a useful safety tool. For example, grounding the metal case of an electrical appliance ensures that it is at zero volts relative to the earth.
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Because a conductor is an equipotential, it can replace what?
- Any equipotential surface
- A point charge
- A field line
- An insulator
Reveal answer
Answer: Any equipotential surface
Source evidence
PDF page 908: Because a conductor is an equipotential, it can replace any equipotential surface. For example, in Figure 19.8 a charged spherical conductor can replace the point charge, and the electric field and potential surfaces outside of it will be unchanged, confirming the contention that a spherical charge distribution is equivalent to a point charge at its center.
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