PHYS 1112 Exam 3 Chapter 20 Conceptual
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if you were a parallel plate capacitor manufacturer, state three ways you might make larger valued capacitors
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increase plate area, decrease separation, and increase the dielectric constant
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state three reasons for adding a dielectric material between the plates of a capacitor
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1. dielectrics do not break down as readily as air, so a higher voltage can be applied without charge passing across the gap 2. a dielectric allows the plates to be placed closer together without touching thus allowing an increased capacitance because the plate separation is less 3. if a dielectric fills the space between the two conductors, it increases the cpacitance
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after being charged from a battery, the plates of a parallel plate capacitor are moved closer together. when they are half as far apart as originally, by how much does the stored energy change
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the capacitance doubles but charge remains the same so energy reduces to half of what it was
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the work done in moving a positive charge against an electric field does not depend on the path chosen in moving the charge in that field. based on the statement, what kind of force field is the electrostatic field
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conservative
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the electron-volt is a unit of
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energy
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a negative charge, if free, tries to move
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from low potential to high potential
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for a proton moving in the direction of the electric field
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its potential energy decreases and its electric potential decreases
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for an electron moving in a direction opposite to the electric field
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its potential energy decreases and its electric potential increases
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two parallel metal plates A and B carry positive and negative charges of equal strength, respectively, as shown in figure 20-1. what is the correct direction for the equipotential lines for this charge configuration?
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horizontal, along the x-axis
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two electric charges +Q and -Q, are separated by a distance d. if you make a graph of the electric potential as a function of the distance along the line connecting the two charges, the point exactly midway between the two charges would
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be neither a relative maximum nor a relative minimum
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two electric charges each equal to +Q, are separated by a distance d. if you make a graph of the electric potential as a function of the distance along the line connecting the two charges, the point exactly midway between the two charges would
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be a relative minimum
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two electric charges each equal to -Q, are separated by a distance d. if you make a graph of the electrical potential as a function of the distance along the line connecting the two charges, the point exactly midway between the two charges would
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be a relative maximum
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a negative charge is moved from point A to point B along an equipotential surface. which of the following statements is true for this case
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no work is required to move the negative charge from point A to point B
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an equipotential surface must be
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perpendicular to the electric field a any point
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a surface on which all points are at the same potential is referred to as
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an equipotential surface
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several elctrons are placed on a hollow conducting sphere. they
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become uniformly distributed on the sphere's outer surface
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which of the following will increase the capacitance of a parallel plate capacitor
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an increase in the plate area and a decrease in the plate separation
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a capacitor consists of a set of two parallel plates of area A separated by a distance d. this capacitor is connected to a battery that maintains a constant potential difference between the plates. if the separation between the plates is doubled, the magnitude of the charge on the plates will
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be cut in half
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a capacitor consists of a set of two parallel plates of area A separated by a distance d. this capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. if the separation between the plate is doubled, the potential difference between the plates will
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double
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a capacitor consists of a set of two parallel plates of area A separated by a distance d. this capacitor is connected to a battery that maintains a constant potential difference between the plates. a slab of dielectric material is inserted in the region between the plates so as to completely fill it. what changes would you observe
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both the charge in the capacitor and its capacitance would change
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which of the following will increase the capacitance between the plates of a parallel plate capacitor
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introduce a dielectric material between the plates
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a dielectric material such as paper is placed between the plates of a capacitor holding a fixed charge. what happens to the electric field between the plates
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becomes weaker
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when a dielectric material is introduced between the plates of a parallel plate capacitor the capacitance increases by a factor of 4. what is the dielectric constant of the material introduced between the plates
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4
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a capacitor consists of a set of two parallel plates of area A separated by a distance d. this capacitor is connected to a battery that maintains a constant potential difference between the plates. if the separation between the plates is doubled, the magnitude of the electrical energy stored on the capacitor will
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be cut in half
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a capacitor consists of a set of two parallel plates of area A separated by a distance d. this capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. if the separation between the plates is doubled, thee electrical energy stored in the capacitor will
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double
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which of the following expressions represents the electrical energy stored by a capacitor
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QV/2 CV^2/2 Q^2/2C
