Name Section General Physics 204 Summer Morning Section 01:750:204 Mayes Exam 1 August 29 th 2016 10:15AM-11:45AM FORM A This exam is 20 multiple choice questions. You may use No. 2 pencils, a calculator, and the equation sheet provided. Answers are represented in scientific notation use calculator format. As an example, 2 x 10 3 is represented as 2E3. Units for answer choices are given in brackets after each question. As an example, [T] after a question indicates the answer should be given in Teslas. DO NOT WRITE IN THE BUBBLE AREA OF THE ANSWER SHEET. Please show your work on the lines of the answer sheet as much as possible.
The following scenario pertains to questions 1-5 You are exploring deep space and find three strange orbs; one black, one white, and one silver. The white orb has a mass of 0.17kg and a -3C charge and you focus on this one. The other orbs have 0.16kg of mass each. The black orb is 1.38m from the white orb and has -2C of charge. The silver is 0.87m from the white orb and has 3C of charge. You remove the white orb from its location and shield the orb in a container on your ship. This, surprisingly, does not change the position of the black or silver orbs which appear to be anchored in place somehow. The location the white orb used to occupy will henceforth be referred to as 'the spot'. Units are in brackets after each question. 1. What will the E-field strength be at the spot? [N/C] A) 2.62E+10 B) -4.51E+10 C) 3.98E+09 D) 2.24E+09 E) 4.51E+10 2. What would the potential (V) be at the spot? [V] A) 1.80E+10 B) -3.78E+09 C) -4.50E+10 D) 2.00E+00 E) 9.00E+09 3. What will the acceleration of the white orb be if it is placed at the spot and released at the moment after its release? [m/s 2 ] A) 4.63E+11 B) 1.54E+11 C) -7.87E+10 D) 3.17E+11 E) -1.76E+01 4. What charge do we have to put directly in the middle of the black and silver orbs to make the field strength at the spot zero? [C] A) -3.69 B) 5.27 C) -2.53 D) -3.37 E) -2.91 5. A rod is rubbed and given a charge. The silver and the black orbs are connected by a copper wire. The charged rod is brought near the black orb from a large distance while remaining in line with both the black and silver orbs. The rod is held there until the charge of the silver orb is zero. The wire is removed then the rod is withdrawn. The white and black orbs are then brought into contact by a copper wire and left for a long period of time. If they are separated, what will the new charge on the white orb be? [C] A) -0.50 B) -1.00 C) 0.50 D) 1.00 E)-2.00
The following scenario pertains to questions 6-13 A simple mass spectrometer consists of charged parallel plates to accelerate charged particles followed by a uniform magnetic field which adjusts their trajectories so that only certain particles curve into a detector. The particles which curve into the detector are analyzed to determine their charge, mass, or prevalence. Throughout this process, it is assumed that the only thing affecting the particles is the mass spectrometer. The particles involved in this case are either individual electrons or nuclei consisting of 3 protons and 3 neutrons. You are in a universe where a proton has a mass of 1.673 x 10-27 kg and a charge of 1.6022 x 10-19 C, a neutron has a mass of 1.675 x 10-27 kg and no charge, and an electron has a mass of 9.11 x 10-31 kg and a charge of -1.6022 x 10-19 C. The plates of the accelerator are squares with sides that are 0.3m long, the charge on one plate is 6 x 10-12 C, and the plates are 0.4m apart. The permittivity of free space is 8.85418782x10-12 F/m and the permeability of free space is 1.25663706 x 10-6 Tm/A. 6. A gaussian surface is the shape of a square box with sides that are half the length of the side of a plate of the accelerator. The gaussian surface is imagined so it is cut exactly in half by the positive plate of the accelerator in the mass spectrometer. Two sides of the gaussian surface are parallel to the surface of the plate and four are perpendicular. What is the flux through this gaussian surface? [Nm 2 /C] A) 0.68 B) 0.02 C) 0.17 D) 0.34 E) 0.09 7. What is the E-field inside the accelerator? [N/C] A) 5.90E-22 B) 2.26 C) 4.78E-24 D) 7.53 E) 6.67E-11 8. What is the potential difference (voltage) between the plates of the accelerator? [V] A) 3.01 B) 1.88E+01 C) 7.53 D) 5.67E+01 E) 1.60E-01 9. If the nucleus made of protons and neutrons is placed in the center of the accelerator, what will its acceleration be? [m/s 2 ] A) 3.64E-44 B) 1.40E+46 C) 4.00E+07 D) 1.43E+35 E) 3.60E+08 10. If the nucleus is allowed to accelerate from rest through the entire accelerator, what will its final velocity be? [m/s] A) 2.88E+08 B) 1.70E+04 C) 1.70E-09 D) 1.71E-22 E) 1.20E+04
11. After accelerating from rest through the entire parallel plate capacitor the particle enters a chamber with a uniform magnetic field of 3.14159 T which curves the particles into a detector. The magnetic field, the path of the particle, and the distance from the particle's entry point to the detector are all perpendicular to each other. How long, in seconds, does it take the particle to hit the detector from the moment it enters the magnetic chamber? [s] A) 4.18E-08 B) 6.56E-08 C) 2.09E-08 D) 1.04E-08 E)1.31E-07 12. How far would an electron have to be accelerated by a field of the same strength to have the same amount of velocity as a nucleus accelerated through the entire accelerator? [m] A) 3.95E-21 B) 3.49E-23 C) 1.74E-23 D) 1.03E-27 E)1.91E+07 13. If an electron enters the 3.14159T uniform magnetic field in the mass spectrometer at a velocity of 314,159m/s perpendicular to the B-field then curves into the detector, how far away from the entry point is the detector? [m] A) 6.59E+23 B) 6.67E+15 C) 7.50E+04 D) 5.34E-14 E) 5.69E-07
The following scenario pertains to questions 14-20 A circuit for light bulbs in a car has a battery with a terminal voltage of 27 V. The internal resistance of this battery is 1.7 Ohms. All bulbs have the same efficiency. The first bulb of this circuit has 70 Ohms and is in series with the battery. After this there are two branches. One branch has the third bulb with 125 Ohms and the fourth bulb with 75 Ohms. The third and fourth bulbs are in series with each other. The other branch has the second and fifth through eighth bulbs. The resistances of all these bulbs in Ohms are R2=50, R5=60, R6=25, R7=94, and R8=112, respectively. The fifth and sixth bulbs are in parallel with each other but in series with all other bulbs in the second branch, which are all in series with each other. Assume all questions begin with this circuit. The permittivity of free space is 8.85418782 x 10-12 F/m and the permeability of free space is 1.25663706-6 T*m/A. The circuit diagram is below. 14. What is the EMF of the battery? [V] A) 27.00 B) 26.75 C) 27.09 D) 27.25 E) 6.68 15. What is the power output of the third brightest bulb in Watts? [W] A) 0.530 B) 0.189 C) 0.883 D) 0.355 E) 0.423 16. You are investigating the resistance of the metal from which the engine block is made. You have a 0.3m x 0.55m x 0.8m rectangular piece of the same metal as the engine block and find the greatest possible resistance is the same as the first bulb in your car. What is the greatest possible current that you could achieve through the block? [A] A) 0.05 B) 1.30 C) 1.02 D) 2.74 E) 3.42
17. How much force will the wire containing bulb 3 exert on a 9.99cm long section of the wire containing bulb 2 if they are 1.59cm apart? [N] A) 6.49E-09 B) 5.17E-03 C) 1.54E-08 D) 1.40E-09 E) 1.78E-08 18. You replace all the bulbs in the original circuit with capacitors of the same capacitance (in Farads) as the magnitude of the resistance in the bulbs. You then charge this circuit with the car battery. The battery is removed and the capacitors are used to run the car stereo which has a power consumption of 330 Watts. How long, in seconds, will the stereo run assuming a constant power consumption? [s] A) 24800 B) 0.032 C) 0.017 D) 37.6 E) 75.3 19. The parallel configuration with bulbs 5 and 6 is replaced with a battery providing half the terminal voltage of the original battery. The new battery is oriented so the same terminals of each battery lead to the same junction. Bulbs 1, 2, 3, 4, 7, and 8 are left in their current configurations. What is the current through the fourth bulb? [A] A) 0.021 B) 0.116 C) 0.095 D) 0.246 E) 0.123 20. You replace the battery in the original circuit with a simple hand generator which consists of a 0.3m long metal rod on an enclosed track. When you push on the rod the area enclosed by the rod and track shrinks. This whole apparatus is in a uniform 90T B- field oriented perpendicular to the surface of the enclosed area. How fast would you have to push the rod to create an EMF equal to the terminal voltage of the original battery? [m/s] A) 1.00 B) 8.10 C) 2430.00 D) 3.33 E) 0.33