Fall2023_Exam1

pdf

School

University of Florida *

*We aren’t endorsed by this school

Course

2049

Subject

Physics

Date

Jan 9, 2024

Type

pdf

Pages

Uploaded by PresidentAtomFinch39

Exam #77777 Exam #77777 Department of Physics University of Florida Instructor: J. Yelton and A. Korytov PHY 2049 Exam 1 October 2023 On my honor, I have neither given nor received unauthorized aid on this examination Name Last: First: Signature: This exam is protected by United States copyright law [Title 17, U.S. Code]. Neither this exam nor any portion thereof may be shared, distributed, or sold in print or digital formats without written permission of the course instructors, who reserve all rights. Directions 1. Print your name on this question sheet and sign it. 2. Code your 5-digit exam code (at the top of this question sheet) on your Scantron in columns 76–80. 3. Code your name and 8-digit UFID on the Scantron. Darken all circles completely on the Scantron using a #2 pencil or dark blue or black ink. Do not make any stray marks or the Scantron may not read properly. 4. Do all scratch work anywhere on this question sheet that you like. At the end of the exam, the question sheet and Scantron are both to be turned in. No credit will be given without both Scantron sheet and question sheet. 5. The answers are rounded, so choose the closest to exact. There is no penalty for guessing.

Exam #77777 Exam #77777 Correct answer marked with ♣ 1. Three point charges of 10 µ C each are placed in the corners of an equilateral triangle with sides of 10 cm. Find the magnitude of the force experienced by each charge. (1) ♣ 156 N (2) 90 N (3) 180 N (4) 270 N (5) 135 N 2. Two identical small spheres, each with mass 100 g and charge q , hang from very light strings, both of length 50 cm (see figure). If the angle θ between the strings is 30 ◦ at equilibrium, what is the magnitude of charge q on each sphere? (1) ♣ 1.4 µ C (2) 2.1 µ C (3) 2.8 µ C (4) 3.5 µ C (5) 4.2 µ C 3. Two point charges q 1 = 1 µ C and q 2 = − 2 µ C are placed and fixed along the x -axis at x 1 = 1 m and x 2 = − 2 m, respectively. If one wants to put a third charge Q somewhere along the x -axis so it is in equilibrium (i.e. the net force acting on it is zero), at what x -coordinate should it be placed? (1) ♣ 8.2 m (2) -0.24 m (3) 0.0 m (4) 2.4 m (5) one needs to know Q 4. Which of the configurations with four charges placed at the corners of squares, as shown below, has the strongest electric field at the square’s center? The plus symbol indicates a positive charge + q , and the minus symbol indicates a negative charge − q . (1) ♣ C (2) A (3) B (4) D (5) insufficient information 5. Two identical positive charges q are placed in the ( x, y )-plane and have coordinates (0 , − 2 d ), and ( − 3 d, 0), where d is some positive number. Find the direction of the electric field at the origin of the coordinate system (0 , 0) with respect to the x -axis. (1) ♣ 66 ◦ (2) 73 ◦ (3) 54 ◦ (4) 47 ◦ (5) 39 ◦ 6. A ring of radius R carrying negative charge Q uniformly distributed along its circumference is placed in the ( x, y ) plane with the ring’s center at the origin of the coordinate system (0 , 0 , 0). A point-like particle with positive charge q is then placed at the origin of the coordinate system. If the particle is displaced along the z -axis, what is the magnitude and direction of the force it experiences as a function of its displacement z , assuming that z ≪ R ? In the following equations, ˆ z stands for a unit vector pointing in the positive direction of the z axis. (1) ♣ − | Qq | k R 3 · z · ˆ z (2) + | Qq | k R 3 · z · ˆ z (3) + | Qq | k R 5 · z 3 · ˆ z (4) − | Qq | k R 5 · z 3 · ˆ z (5) + | Qq | k R · 1 z · ˆ z

Exam #77777 Exam #77777 7. A solid conducting shell with inner radius R and outer radius 2 R has a net charge of +4 mC placed on it. If a +1 mC point charge is at the center of sphere as shown, how much charge is located on the outer surface of the conducting shell? (1) ♣ 5 mC (2) 4 mC (3) 6 mC (4) 0 mC (5) 1 mC 8. The figure shows a line of negative charge with linear charge density λ = − 2 µ C/m. Calculate the electric flux through a cylinder of height h = 0 . 75m and radius R = 2m. (1) ♣ − 1 . 7 × 10 5 N · m 2 / C (2) − 3 . 4 × 10 5 N · m 2 / C (3) − 6 . 8 × 10 5 N · m 2 / C (4) − 2 . 3 × 10 4 N · m 2 / C (5) − 4 . 6 × 10 5 N · m 2 / C 9. An infinite slab of thickness 0.20 meters has a uniform charge density of ρ = 4.5 nC/ m 3 . What is the magnitude of the electric field at a point inside the slab, 0.05 meters from one surface? (1) ♣ 25 N/C (2) 13 N/C (3) 51 N/C (4) 38 N/C (5) 76 N/C 10. An particle of mass m and charge q is shot directly toward a flat metal surface that has surface charge density of σ . The initial kinetic energy of the particle is K and it started at a distance D from the plate. The particles comes to a momentary stop at a distance d from the plate. What is d ? (1) ♣ D − Kϵ 0 / ( qσ ) (2) D − 2 Kϵ 0 / ( qσ ) (3) Kϵ 0 / ( qσ ) (4) D − qσ/ ( Kϵ 0 ) (5) D − qσ/ (2 Kϵ 0 ) 11. A uniform electric field ⃗ E is of strength E x , E y , E z = (1,5,4) N/C. A square patch of is placed in the ( x, y )-plane, with boundaries at x =0, x =2, y =0, and y =2. What is the magnitude of the flux of electric field going though the patch? (1) ♣ 16 N · m 2 /C (2) 4 N · m 2 /C (3) 8 N · m 2 /C (4) 20 N · m 2 /C (5) 2 N · m 2 /C 12. Four point charges of +1.0 nC, +1.0 nC, -2.0 nC and +2.0 nC are arranged at the corners of a square of side length 0.60 m as shown What is the electric potential at a location at the center of the square (take V( ∞ )=0). (1) ♣ 42 V (2) 106 V (3) 60 V (4) 21 V (5) 3 . 3 V 13. The electric potential (voltage) in a particular region of space is given by the function V ( x, y, z ) = 5 xy 2 /z 2 ). What is the value of the z-component of the electric field ( E z ) at a location x =2, y =2, z =2? (Consistent units are assumed.) (1) ♣ +10 (2) -5 (3) -10 (4) +5 (5) +20

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Exam #77777 Exam #77777 14. A parallel-plate capacitor with no media between its plates has capacitance C . If the gap between the capacitor’s plates is doubled and then filled with dielectric matter of dielectric constant κ = 4, what is the capacitance of such a new capacitor? (1) ♣ 2 C (2) 8 C (3) C (4) C /8 (5) C /2 15. A 1 µ F capacitor is charged to a difference of potentials V = 18 kV. It is then connected in parallel to another (initially uncharged) capacitor of capacitance 2 µ F. How much energy would be released as a result of such a connection? (1) ♣ 108 J (2) 18 J (3) 81 J (4) 36 J (5) 54 J 16. In the figure at right, all the capacitors have the value of 2 µ F, and the voltage of the battery is 9 V. What is the charge on the capacitor marked A? (1) ♣ 12 µ C (2) 18 µ C (3) 9 µ C (4) 36 µ C (5) 24 µ C 17. A copper wire has a radius of 0.5 mm and carries current 2 A. What is the drift velocity of electrons? Copper has one free electron per atom. The atomic mass of copper is 63.5 times the mass of a proton. The copper density is 8.94 g/cm 3 . (1) ♣ 0.2 mm/s (2) 0.1 mm/s (3) 0.3 mm/s (4) 0.4 mm/s (5) 0.5 mm/s 18. A wire has resistance R . The wire is uniformly stretched to become twice longer, while maintaining its volume. What is its new resistance? (1) ♣ 4 R (2) 2 R (3) 8 R (4) R /2 (5) R /8 19. A certain resistor dissipates 1 W when connected to a 1.5 V potential difference (one AA battery). When connected to a 3 V potential difference (2 AA batteries in series), this resistor will dissipate: (1) ♣ 4 W (2) 3 W (3) 2 W (4) 6 W (5) 9 W 20. In a very simplified view, a hydrogen atom comprises a proton and an electron separated by a typical distance of 10 − 10 m. Estimate how much energy is needed to ionize a single hydrogen atom (separate the electron from the proton by an infinitely large distance). (1) ♣ 14 e V (2) 7 e V (3) 22 e V (4) 29 e V (5) 36 e V

Exam #77777 Exam #77777 Scratch paper

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Exam #77777 Exam #77777 Scratch paper

Exam #77777 Exam #77777

Exam #77777 Exam #77777 Details of Master Exam Questions Total of 20 QQ, 0 CQ, 0 RQ questions (0 distinct RQ questions) * Total of 20 questions defined (20 for each student exam) * Total weight is 20.00 for each student exam * Total of 8 figures defined Shuffle Q Type aType Wght #fig #ans ans? Correct Short text 1 QQ Single 1.00 0 5 Yes 1 Three point charges of 10 µ C each are placed in the 2 QQ Single 1.00 1 5 Yes 1 Two identical small spheres, each with mass 100 g and c 3 QQ Single 1.00 0 5 Yes 1 Two point charges q 1 = 1 µ C and q 2 = − 2 µ C are pl 4 QQ Single 1.00 1 5 Yes 1 Which of the configurations with four charges placed at 5 QQ Single 1.00 0 5 Yes 1 Two identical positive charges q are placed in the 6 QQ Single 1.00 0 5 Yes 1 A ring of radius R carrying negative charge Q unifo 7 QQ Single 1.00 1 5 Yes 1 A solid conducting shell with inner radius R and oute 8 QQ Single 1.00 1 5 Yes 1 The figure shows a line of negative charge with linear 9 QQ Single 1.00 0 5 Yes 1 An infinite slab of thickness 0.20 meters has a uniform 10 QQ Single 1.00 0 5 Yes 1 An particle of mass m and charge q is shot directly 11 QQ Single 1.00 0 5 Yes 1 A uniform electric field ⃗ E is of strength 12 QQ Single 1.00 1 5 Yes 1 Four point charges of +1.0 nC, +1.0 nC, -2.0 nC and +2. 13 QQ Single 1.00 0 5 Yes 1 The electric potential (voltage) in a particular region 14 QQ Single 1.00 0 5 Yes 1 A parallel-plate capacitor with no media between its pl 15 QQ Single 1.00 0 5 Yes 1 A 1 µ F capacitor is charged to a difference of pote 16 QQ Single 1.00 1 5 Yes 1 In the figure at right, all the capacitors have the val 17 QQ Single 1.00 0 5 Yes 1 A copper wire has a radius of 0.5 mm and carries curren 18 QQ Single 1.00 0 5 Yes 1 A wire has resistance R . The wire is uniformly stretc 19 QQ Single 1.00 0 5 Yes 1 A certain resistor dissipates 1 W when connected to a 1 20 QQ Single 1.00 0 5 Yes 1 In a very simplified view, a hydrogen atom comprises a

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Fall2023_Exam1

Related Documents