Physics 102 Midterm 06W

Physics 102 Midterm 06W - L_J First Letter Last Name:...

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Unformatted text preview: L_J First Letter Last Name: Student’s Name: Student Number: Physics 102 06W — Mid-terml 1. Clearly show all of your work. 2. Use pen. 3. Simple scientific calculator only - no graphin Question 1 (7 marks) A radioactive sample has an initial activity of 1,000 Bq, 20 minutes later its activity is 5.1 Bq. a) Determine the half-life of the radioactive material. calculators (abm‘m or \‘58 8 Analysis of the material shows that it contains both Gallium-64 (atomic mass 326a: 63.936838u) and Zinc-64 (atomic mass :32]: =63.929147u). a ‘ V Useful masses: me =0.000549u; mp =1.007276u; memm = 1.007825; m" =1.008665u b) Which nuclide (Ga-64 or Zn—64) is the parent nuclide and which is the daughter nuclide? got—w c) Write the decay reaction and determine the reaction energy, report your answer in MeV Question 2a (4 marks) Point charges are arranged at three of the four comers of a square with side length L, as shown below: " a) determine the electric field at the origin, report your answer in unit vector form and in terms of k, Q and L. \40 A ’.\ T,” ~3T—H t ——\:H a} Limos k. ( '2. e = 945% b) In addition, report your answer as a magnitude and direction with respect to the positive x—axis. Question 2b ( 3 marks) Three particles are fixed in place at the comers 2‘13 2‘1 ,q of an equilateral triangle. The particles are charged as shown. I A \x‘ I I B ~ \ J. ............. -33 ____________ _.‘.‘ 2q q r“; b2Q 2" -. 2“ ,e x c ‘x D ‘ ‘ 4' .............. -f‘o J: ............. -3. a“ '2‘] 5‘ 2" Rank the magnitude of the electric force on the lower left particle. Greatest Q [A Q) Q Least MT] 06W P107. Question 3a (2 marks) Current flows through a copper wire with three segments A, B and C. The ratio of the diameters is A:B:C = 321:5. How much larger magnitude isthe drift velocity vd in region B compared to region C? Circle the correct answer 'A: same magnitude B: 25 times greater C: 5 times greater D: It's slower in region B E: None/don‘t know Question 3b (2 marks) 3 A fuse in an electrical circuit is a wire that is designed to melt and thereby open the circuit, if the current exceeds a predetermined value. Suppose the material to be used in the fuse melts when the current density is 400 A/cm’. What diameter of wire should be used to make a fuse that limits the current to 1.0 A? or ose, QM MT] 06W P107. Question 4a (3 marks) Four identical positive charges are each launched with a speed v0 from a point between the plates of a parallel-plate capacitor (creates a uniform electric field). The plates are very large and only a small portion near the centre is shown below. Charge A is lauched towards the negative plate I A 9—» Charge B is launched parallel to the plates Charge C is launched at an angle of 45 ° towards the positive plate Charge D is launched directly towards the positive plate, but does not hit the plate ----x--.__>—__-_--_ O «AD ._—-- Rank the speeds of charges A—D just before they hit the negative plate. Greatest _________. ._______ ___._._ ._————-—- Lea“ SCAN 3M3\ Carefully explain your reasoning Question 4b (4 marks) Charge D is a proton (mass=1.67x10‘27 kg) that is launched with a speed of 5.0x104 m/s and the electric field has magnitude of 1000N/C. How far does the proton travel before it stops and reverses direction? \ \ 3 CM MTl 06W P107. Question 5a (3 marks) Two very large insulating parallel charged sheets are separated by a distance 4d. The distance between the sheets is very small compared to the dimensions of the sheets. The left sheet has a charge density of +9.0 uC/mz, and the sheet on the right has a charge density of -6.0 uC/mz. Clearly indicate the direction of the electric fields due to each plate +9 ’uC/‘ml " —6 yClml ‘ A B D E F -+—-+ - — — — —+—-+ ———————— ~—1 ——————— —+—- 14 d d d—>l< d—>l< 2d d—>l<—2d——>I Portions of l ' very large sheets Rank th the electric field at points A-F. Greatest - Least C7 a: B 5E 53F Question 5b (2 marks) Shown below is a graph of the electric field versus position for a situation involving spherical shaped charged insulators/ and /or conductors. A B 0 Position Draw the physical sittiation that this graph represents and label each object clearly. \M‘.“:G m\ A O...A (3%,?3 hOY‘l" ch‘sowd‘vf (3 -—C. CMA’" MT] 06W P107. ...
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Physics 102 Midterm 06W - L_J First Letter Last Name:...

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