Transcript
Study Guide re: Exam #1 - PHYS 2064
Two isolated copper plates, each of area 0.4 m2, carry opposite charges of magnitude
7.08 × 10-10 coulombs. They are placed opposite each other in parallel alignment, with a spacing of 2 mm. What will be the potential difference between the plates when their spacing is increased to 4 cm?
1032548233636A) 7.6 V B) 3.2 V C) 8 V D) 0.4 V E) 3.04 V
Two equally charged spheres of mass 1.0 g are placed 2.0 cm apart. When released, they begin to accelerate at 414 m/s2. What is the magnitude of the charge on each sphere?
103254823938895 nC B) 140 nC C) 75 nC D) 120 nC
A proton with a speed of 2.0 x 105 m/s falls through a potential difference V and thereby increases its speed to 4.0 x 105 m/s. Through what potential difference did the proton fall?
1032548240776A) 840 V B) 210 V C) 100 V D) 1,000 V E) 630 V
The capacitance of a capacitor depends on
the charge on it.
the energy stored in it.
the potential difference across it.
More than one of these.
1032548262869None of these.
The resistivity of gold is 2.44 × 10-8 fi · m at a temperature of 20°C. A gold wire, 0.5 mm in diameter and 44 cm long, carries a current of 380 mA. The number of electrons per second passing a given cross section of the wire, is closest to:
A) 2.8 × 1014
B) 6.3 × 1015
C) 2.4 × 1018
D) 2.4 × 1017
1032548322663E) 1.2 × 1022
Two electrons are passing 20.0 mm apart. What is the electric repulsive force that they exert on each other? (The value of k is 9.0 × 109 N·m2/C2.)
A) 5.8 × 10-27 N B) 2.3 N
1032548310519C) 2.3 × 1010 N D) 5.8 × 10-25 N
When electric current is flowing in a metal, the electrons are moving
at the speed of light.
at nearly the speed of light.
at the speed of sound in air.
at none of the above speeds.
1032548224408at the speed of sound in the metal.
Three capacitors of equal capacitance are arranged as shown in Figure 18.9. The voltage drop across C1 is 10.0 V. What is the voltage drop across C3?
Figure 18.9
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1032548249572A) 40 V B) 10.0 V C) 20 V D) 30 V
Two identical small charged spheres are a certain distance apart, and each initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually diminishes on both spheres. When each of the spheres has lost half its initial charge, the magnitude of the electrostatic force will be
1032548240009A) 1/16 F B) 1/4 F C) 1/8 F D) 1/2 F
One charged plastic object is vertically above another in a test tube as shown in Figure
17.5. The objects are in equilibrium a distance d apart.
Figure 17.5
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If the charge on each object is doubled, the distance between them in the test tube would become
1032548269892 A) 2d
B) 4d C) 8d D) 2d
An electric device delivers a current of 5.0 A to a device. How many electrons flow through this device in 10 s? ( e = 1.60 × 10- 19 C)
1032548244728A) 2.0 B) 0.20 C) 31 x 1020 D) 20 E) 3.1 x 1020
Suppose a van de Graaff generator builds a negative static charge, and a grounded conductor is placed near enough to it so that a 7.0 µC of negative charge arcs to the conductor. Calculate the number of electrons that are transferred.
A) 4.38 × 1013 B) 1.12 ×
10-18
C) 43.8 D) 7.0
An electron was accelerated from rest through a potential difference of 1,500 V. What
is its speed?
A) 1.1 × 107 m/s B) 1.9 × 107 m/s
C) 1.5 × 107 m/s D) 2.3 × 107 m/s
Two identically charged balls are a certain distance apart. The vectors in Figure 17.8 show the magnitude and direction of the electrostatic force on each ball.
Figure 17.8
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Suppose the charge on the left ball is now doubled (represented by two plus signs). Which diagram below best represents the forces that now act on the two balls?
1350717212261A)
B)
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D)
An electron is initially moving to the right when it enters a uniform electric field directed upwards. Which trajectory shown in Figure 17.10 will the electron follow?
Figure 17.10
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Trajectory W
Trajectory X C) Trajectory Y D) Trajectory Z
Two conductors are joined by a long copper wire. Thus
no free charge can be present on either conductor.
each conductor must be at the same potential.
the electric field at the surface of each conductor is the same.
the potential on the wire is the average of the potential of each conductor.
1032548262869each conductor carries the same free charge.
Each plate of a parallel-plate air capacitor has an area of 0.0040 m2, and the separation of the plates is 0.070 mm. An electric field of 5.0 × 106 V/m is present between the plates. The potential difference across the capacitor is closest to:
1032548235199A) 583 V B) 700 V C) 350 V D) 467 V E) 233 V
Two capacitors, one a 4.0 µF capacitor, C1, and the other a 7.0 µF capacitor, C2, are connected in series. If a 90.0 V voltage source is applied to the capacitors, as shown in Figure 18.7, find the voltage drop across the 4.0 µF capacitor.
Figure 18.7
1032548240631A) 54 V B) 9.0 V C) 36 V D) 60 V
The figure shows a steady electric current passing through a wire with a narrow region. What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?
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The drift velocity decreases from A to B and increases from B to C.
The drift velocity decreases all the time.
The drift velocity remains constant.
The drift velocity increases from A to B and decreases from B to C.
The drift velocity increases all the time.
A plastic rod is charged up by rubbing a wool cloth, and brought to an initially neutral metallic sphere. It is allowed to touch the sphere for a few seconds, and then is separated from the sphere by a small distance. After the rod is separated, the rod
feels no force due to the sphere.
is attracted to the sphere.
1032548262234is repelled by the sphere.
1032548184644
Figure 17.11 shows electric field lines arising from two small charged particles P and Q.
Figure 17.11
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Consider the following two statements:
The charge on P is smaller than the charge on Q.
The electrostatic force on P is smaller than that on Q.
Which of the above statements are true?
A) Only i. B) Only ii.
1032548262234C) Both i and ii. D) Neither i nor ii.
A small glass bead has been charged to 1.9 nC. What is the strength of the electric field
2.0 cm from the center of the bead?
A) 8.1 × 10-5 N/C B) 4.3 × 104 N/C
C) 8.5 × 102 N/C D) 8.5 × 10-7 N/C
A hydrogen atom consists of a proton and an electron. If the orbital radius of the electron increases, the potential energy of the electron
decreases.
increases.
remains the same.
1032548262869depends on the zero point of the potential.
An object with a 5.0 µC charge is accelerating at 0.0050 m/s2 due to an electric field. If the object has a mass of 2.0 mg, what is the magnitude of the electric field?
1032548252735A) -0.0020 N/C B) -2.0 N/C C) 2.0 N/C D) 0.0020 N/C
A positive test charge q is released near a positive fixed charge Q. As q moves away from Q, it will move with
A) constant velocity. B) increasing acceleration.
1032548262221C) decreasing acceleration. D) constant acceleration.
A hydrogen nucleus, which has a charge e, is situated to the left of a carbon nucleus, which has a charge 6e. Which statement is true?
The electrical force experienced by the hydrogen nucleus is to the right, and the magnitude is equal to the
force exerted on the carbon nucleus.
The electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is less than the force exerted on the carbon nucleus.
The electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is equal to the force exerted on the carbon nucleus.
1032548436300The electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is greater than the force exerted on the carbon nucleus.
Answer Key
Testname: EXAM1-STUDY_GUIDE
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