# Electricity Quiz 21-22

## Unlock all answers in this set

question
A particle with charge 3.20×10−19 C is placed on the x axis in a region where the electric potential due to other charges increases in the +x direction but does not change in the y or z direction. The particle, initially at rest, is acted upon only by the electric force and moves from point a to point b along the x axis, increasing its kinetic energy by 1.60×10−19 J . In what direction and through what potential difference Vb−Va does the particle move? The particle moves to the left through a potential difference of Vb−Va= 0.500 V . The particle moves to the left through a potential difference of Vb−Va= -0.500 V The particle moves to the right through a potential difference of Vb−Va= 0.500 V . The particle moves to the right through a potential difference of Vb−Va= -0.500 V . The particle moves to the left through a potential difference of Vb−Va= 5.00 V . The particle moves to the right through a potential difference of Vb−Va= -5.00 V .
The particle moves to the left through a potential difference of Vb−Va= -0.500 V
question
A proton with an initial speed of 700,000 m/s is brought to rest by an electric field. Did the proton move into a region of higher potential or lower potential? Because the proton is a negative charge and it accelerates as it travels, it must be moving from a region of higher potential to a region of lower potential. Because the proton is a positive charge and it slows down as it travels, it must be moving from a region of lower potential to a region of higher potential. Because the proton is a negative charge and it accelerates as it travels, it must be moving from a region of lower potential to a region of higher potential. Because the proton is a positive charge and it slows down as it travels, it must be moving from a region of higher potential to a region of lower potential. Submit
Because the proton is a positive charge and it slows down as it travels, it must be moving from a region of lower potential to a region of higher potential.
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What was the potential difference that stopped the proton?
2600V
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what was the initial ke of the proton in electron volts
2600eV
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mechanical energy is conserved in the presence of which of the following types of forces
gravitational magnetic electrostatic
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which of the following quantities are unknown Kf+qVf=Ki+qVi. To practice Problem-Solving Strategy 21.1 Conservation of energy in charge interactions. An alpha particle (α), which is the same as a helium-4 nucleus, is momentarily at rest in a region of space occupied by an electric field. The particle then begins to move. Find the speed of the alpha particle after it has moved through a potential difference of −3.45×10−3 V . The charge and the mass of an alpha particle are qα = 3.20×10−19 C and mα = 6.68×10−27 kg , respectively.
the value of the electric potential at the final position of the alpha particle the value of the electric potential at the initial position of the alpha particle the final speed of the alpha particle The unknown quantity that you have to find is the final speed of the alpha particle, (vf)α. Although you do not know the electric potential at the initial and final positions, you do know the difference between these values, ΔV=Vf−Vi= −3.45×10−3 V . Before you start creating the equation you will use to solve for (vf)α, first draw a before-and-after visual overview.
question
What is the value of the change in potential energy, ΔU=Uf−Ui, of the alpha particle?
ΔU = −1.10×10−21 J Submit
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What is the final velocity of the alpha particle, (vf)α?
(vf)α = 575 m/s
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If you had carried out the algebra using variables before plugging numbers into your expressions, you would have found that (vf)α=−2qαΔVmα−−−−−−−√, where ΔV is measured in volts. To verify that this expression for (vf)α has the correct units of velocity, you need to perform some unit analysis. Begin by finding the equivalent of a volt in terms of basic SI units. What is a volt in terms of mete
volt = kgm2Cs2 Submit
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In the figure(Figure 1)there are two point charges, +q and −q. There are also six positions, labeled A through F, at various distances from the two point charges. You will be asked about the electric potential at the different points (A through F). C A. B. +q -q E F D
most positive B A neutral D=C F. E most negative
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To review the meaning of capacitance and ways of changing the capacitance of a parallel-plate capacitor. Capacitance is one of the central concepts in electrostatics. Understanding its meaning and the difference between its definition and the ways of calculating capacitance can be challenging at first. This tutorial is meant to help you become more comfortable with capacitance. Recall the fundamental formula for capacitance: C=Q/V, where C is the capacitance in farads, Q is the charge stored on the plates in coulombs, and V is the potential difference (or voltage) between the plates. In the following problems it may help to keep in mind that the voltage is related to the strength of the electric field E and the distance between the plates, d, by V=Ed. what purport of objects is best measured by their capacitance
the ability to store charge
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To review the meaning of capacitance and ways of changing the capacitance of a parallel-plate capacitor. Capacitance is one of the central concepts in electrostatics. Understanding its meaning and the difference between its definition and the ways of calculating capacitance can be challenging at first. This tutorial is meant to help you become more comfortable with capacitance. Recall the fundamental formula for capacitance: C=Q/V, where C is the capacitance in farads, Q is the charge stored on the plates in coulombs, and V is the potential difference (or voltage) between the plates. In the following problems it may help to keep in mind that the voltage is related to the strength of the electric field E and the distance between the plates, d, by V=Ed. consider an air-filled charged capacitor two can its capacitance be increased
decrease the spacing between the plates of the capacitor
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To review the meaning of capacitance and ways of changing the capacitance of a parallel-plate capacitor. Capacitance is one of the central concepts in electrostatics. Understanding its meaning and the difference between its definition and the ways of calculating capacitance can be challenging at first. This tutorial is meant to help you become more comfortable with capacitance. Recall the fundamental formula for capacitance: C=Q/V, where C is the capacitance in farads, Q is the charge stored on the plates in coulombs, and V is the potential difference (or voltage) between the plates. In the following problems it may help to keep in mind that the voltage is related to the strength of the electric field E and the distance between the plates, d, by V=Ed. consider a charged parallel plate capacitor how can its capacitance be halved
double the plate separation halve the plate area
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To review the meaning of capacitance and ways of changing the capacitance of a parallel-plate capacitor. Capacitance is one of the central concepts in electrostatics. Understanding its meaning and the difference between its definition and the ways of calculating capacitance can be challenging at first. This tutorial is meant to help you become more comfortable with capacitance. Recall the fundamental formula for capacitance: C=Q/V, where C is the capacitance in farads, Q is the charge stored on the plates in coulombs, and V is the potential difference (or voltage) between the plates. In the following problems it may help to keep in mind that the voltage is related to the strength of the electric field E and the distance between the plates, d, by V=Ed. consider a charged parallel plate capacitor which combination of changes would quadruple its capacitance
halve the plate separation and double the plate area
question
Suppose two parallel-plate capacitors have the same charge Q, but the area of capacitor 1 is A and the area of capacitor 2 is 2A. if the spacing between the plates d is the same in both capacitors and the voltage across capacitor 1 is V what is the voltage across capacitor 2
v/2 Even though the spacing between the plates is the same in both capacitors, the capacitor with the larger plates has a lower voltage between its plates. In fact, because the capacitors are equally charged, capacitor 2 has a smaller surface charge density, and therefore a weaker electric field between its plates. Since the voltage between two parallel plates is proportional to the electric field, capacitor 2 also has a lower voltage.
question
Suppose two parallel-plate capacitors have the same charge Q, but the area of capacitor 1 is A and the area of capacitor 2 is 2A. if the spacing between the plates in capacitor 1 is d what should the spacing between the plates in capacitor 2 be to make the capacitance of the two capacitors =
2d
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Review | Constants Each part of (Figure 1) shows one or more point charges. The charges have equal magnitudes. for case a if a positive charge is moved from position I to position f does the electric potential energy increase decrease or stay the same I. +. f
electric potential energy stays the same
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Review | Constants Each part of (Figure 1) shows one or more point charges. The charges have equal magnitudes. for case b if a positive charge is moved from position I to position f does the electric potential energy increase decrease or stay the same f + I +
electric potential energy decreases
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Review | Constants Each part of (Figure 1) shows one or more point charges. The charges have equal magnitudes. for case c if a positive charge is moved from position I to position f does the electric potential enerft increase decrease or stay the same I - f
electric potential energy increase
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Review | Constants Each part of (Figure 1) shows one or more point charges. The charges have equal magnitudes. for gas ed if a positive charge is moved from position I to position f does the electric potential energy increase decrease ro stay the same + I f
electric potential energy decreases
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Each part of the figure shows three points in the vicinity of two point charges. The charges have equal magnitudes. (Figure 1) ->rank in order from largest to smallest the potentials . + . + .
2> 1=3
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Each part of the figure shows three points in the vicinity of two point charges. The charges have equal magnitudes. (Figure 1) ->rank in order from largest to smallest the potentials . + . - .
1>2>3
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Each part of the figure shows three points in the vicinity of two point charges. The charges have equal magnitudes. (Figure 1) ->rank in order from largest to smallest the potentials 1 + 2 + 3
2>1=3
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Each part of the figure shows three points in the vicinity of two point charges. The charges have equal magnitudes. (Figure 1) ->rank in order from largest to smallest the potentials 1 + 2 - 3
3=1=2
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the electric potential is 300V at x=0cm is -100V at x=5cm and varies linearly with x Part complete If a positive charge is released from rest at x = 2.5 cm, a
move to the right
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an atom of helium and one of argon are singly ionized - one electron is removed from each the two ions are then accelerated from rest by the electric field between two plate with a potential difference of 150V what happens after the two ions accelerate from one plate to the other
both have the same KE
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A Na+ ion moves from inside a cell, where the electric potential is -70 mV, to outside the cell, where the potential is 0 V. What is the change in the ion's electric potential energy as it moves from inside to outside the cell? does its energy increase or decrease
ΔUelec = 7.0×10−2 eV Submit energy increases
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To understand electrical potential, electrical potential energy, and the relationship between them. Electric potential and electric potential energy are related but different concepts. Be careful not to confuse the terms. Electrical potential energy UE is the potential energy that a charge q has due to its position relative to other charges. The electric potential V at a specific position is a measure of the amount of potential energy per unit charge a particle of net charge q would have at that position. In other words, if a charge q has an electric potential energy UE, the electric potential V at the location of q is V=UEq. Recall that the gravitational potential energy (Ug=mgy) of an object of mass m depends on where you define y=0. The difference ΔUg in gravitational potential energy between two points is the physically relevant quantity. Similarly, for electric potential energy, the important quantity is the change in electric potential energy: ΔUE=qΔV. This is why we often just measure the potential difference ΔV. When we say that the potential of a car battery is 12 V, we mean that the potential difference between the positive and negative terminals of the battery is 12 V. Mustang Sally just finished restoring her 1965 Ford Mustang car. To save money, she did not get a new battery. When she tries to start the car, she discovers that the battery is dead (an insufficient or zero voltage difference across the battery terminals) and so she will need a jump start. Here is how she accomplishes the jump start: She connects a red jumper cable (wire) from the positive terminal of the dead battery to the positive terminal of a fully functional new battery. She connects one end of a black jumper cable to the negative terminal of the new battery. She then connects the other end of the black jumper cable to the negative terminal of the dead battery. The new battery (now in a parallel with the dead battery) is now part of the circuit and the car can be jump started. The car starter motor is effectively drawing current from the new battery. After the car with the dead battery is running, the cables can be disconnected in the reverse order that they were connected. While unhooking the jumper cables, the positive and negative cables almost touch and a spark jumps between the ends of the cables. This spark is caused by the movement of electrons through the air between the battery terminals. In what direction are the electrons traveling during the spark?
the electrons are traveling from the negative to the positive terminal Correct The positive terminal is at a higher potential than the negative terminal. Unless provided with energy, positive charges will flow from a high to a low potential, and negatively charged electrons will flow from a low to a high potential. The table below summarizes this movement. ΔUE q ΔV Direction of motion − + − high to low potential − − + low to high potential
question
There is a 12 V potential difference between the positive and negative ends of the jumper cables, which are a short distance apart. An electron at the negative end ready to jump to the positive end has a certain amount of potential energy. On what quantities does this electrical potential energy depend?
only the potential difference and the charge
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Assume that two of the electrons at the negative terminal have attached themselves to a nearby neutral atom. There is now a negative ion with a charge −2e at this terminal. What are the electric potential and electric potential energy of the negative ion relative to the electron?
the electric potential is the same and the electric potential energy is twice as much
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What is the electric potential energy of an electron at the negative end of the cable, relative to the positive end of the cable? In other words, assume that the electric potential of the positive terminal is 0 V and that of the negative terminal is −12V. Recall that e=1.60×10−19C.
UE = 1.92×10−18 J
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Part complete At the negative terminal of the battery the electron has electric potential energy. What happens to this energy as the electron jumps from the negative to the positive terminal?
converted to KE
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This problem explores the behavior of charge on conductors. We take as an example a long conducting rod suspended by insulating strings. Assume that the rod is initially electrically neutral. For convenience we will refer to the left end of the rod as end A, and the right end of the rod as end B. In the answer options for this problem, "strongly attracted/repelled" means "attracted/repelled with a force of magnitude similar to that which would exist between two charged balls. sphere negative bar is neutral on both A and B is A small metal ball is given a negative charge, then brought near (i.e., within about 1/10 the length of the rod) to end A of the rod (Figure 1). What happens to end A of the rod when the ball approaches it closely this first time?
it is strongly attracted
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This problem explores the behavior of charge on conductors. We take as an example a long conducting rod suspended by insulating strings. Assume that the rod is initially electrically neutral. For convenience we will refer to the left end of the rod as end A, and the right end of the rod as end B. In the answer options for this problem, "strongly attracted/repelled" means "attracted/repelled with a force of magnitude similar to that which would exist between two charged balls. sphere negative bar is neutral on both A and B is after a great many contacts with the charged ball how is the charge on the rod arranged (when the charged ball is far away)
there is negative charge spread every on both ends
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This problem explores the behavior of charge on conductors. We take as an example a long conducting rod suspended by insulating strings. Assume that the rod is initially electrically neutral. For convenience we will refer to the left end of the rod as end A, and the right end of the rod as end B. In the answer options for this problem, "strongly attracted/repelled" means "attracted/repelled with a force of magnitude similar to that which would exist between two charged balls. sphere negative bar is neutral on both A and B is how does end A of the rod react when the charged ball approaches it after a great many previous contacts with end A assume the the phrase a heat many means that the total charge on the rod dominates any charge movement induced by the near presence of the charged ball
it is strongly repelled
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This problem explores the behavior of charge on conductors. We take as an example a long conducting rod suspended by insulating strings. Assume that the rod is initially electrically neutral. For convenience we will refer to the left end of the rod as end A, and the right end of the rod as end B. In the answer options for this problem, "strongly attracted/repelled" means "attracted/repelled with a force of magnitude similar to that which would exist between two charged balls. sphere negative bar is neutral on both A and B is how does end B of the rod react when the charged ball approaches it after a great many previous contacts with end A
it is strongly repelled
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A plastic rod that has been charged to -15.0nC touches a metal sphere. Afterward, the rod's charge is -10.0nC. what kind of charged particle was transferred between the rod and the sphere
electrons
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A plastic rod that has been charged to -15.0nC touches a metal sphere. Afterward, the rod's charge is -10.0nC. in which direction was the charged particle transferred between rod and sphere ? that is did it move from the rod to the sphere or from the sphere to the rod
from the rod to the sphere
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A plastic rod that has been charged to -15.0nC touches a metal sphere. Afterward, the rod's charge is -10.0nC. how many charged particles were transferred
N= 3.13 E10
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Part complete A glass marble is rubbed against a piece of silk. As a result the piece of fabric acquires extra electrons. What happens to the glass marble?
the marble has lost the same number of electrons acquired by the piece of silk the marble acquires a positive charge and attracts the piece of silk
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Two glass marbles (1 and 2), each supported by a nylon thread, are rubbed against a piece of silk and then are placed near a third glass marble (3), also supported by a similar thread. Assuming that marble 3 has not been in contact with the piece of fabric, which of the following statements best describes the situation when the three marbles are brought together? To keep things simple in this Tutorial, we will ignore the effects of polarization and just focus on the overall charge of each object.
marbles 1 and 2 repel each other but no interactions occurs with marble 3
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A+ B- C+ A:1nC B:-1nC C:4nC distance between all 1cm and 1cm what is the magnitude of the electric force on charge A in figure 1
F=0N
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A:1nC B:-1nC C:4nC distance between all 1cm and 1cm WHAT IS THE DIRECTION OF THE ELECTRIC FORCE ON CHARGE A IN THE FIGURE
THE FORCE IS ZERO
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A small object A, electrically charged, creates an electric field. At a point P located 0.250 m directly north of A, the field has a value of 40.0 N/C directed to the south.
-2.8E-10C
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you are given two metal spheres on portable insulating stands, a glass rod and a piece of silk
put the two metal spheres in contact with each other. then rub the glass rod on the silk to charge the rod positively hence to charge piece of silk negatively . bring the rod near but not touching one of the spheres operate the spheres and remove to the rod
question
metal rod positive another rod with ball touching neutral They are originally neutral. A positively charged rod is brought near (but not touching) the far end of A. While the charged rod is still close, A and B are separated. The charged rod is then withdrawn. Is the sphere then positively charged, negatively charged, or neutral?
positively charged
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is there a point between a 10nC charge and a 20nC charge at which the electric field is zero if so which charge is this point closer to
10nC yes
question
is there a point between a 10nC charge and a -20nC charge at which the electric field is zero
no
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At one point in space, the electric potential energy of a 20 nC charge is 68 μJ . what is the electric potential at this point if a 25nC charge were placed at this point what would its electric potential energy be
3400V U=85microJ
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What potential difference is needed to accelerate a He+ ion (charge +e, mass 4u) from rest to a speed of 2.0×106 m/s ?
ΔV = −8.4×104 V
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Review | Constants An electron with an initial speed of 380,000 m/s is brought to rest by an electric field. did the electron move into a region of higher potential or lower potential