Equations: 1 1 Constants: q q v v F = k F = qe e = 1.6 x 1-19 C q 1 q 1 9 E = k = k = = 9 1 Nm / C 4πε 4 πε Φ = E da Φ V Total v v q = E da = = V f V i = W q enclosed ε = E ds U e V = q q V V V V = k E = V = iˆ + ˆj + kˆ x y z Q C = V ε = 8.85 x 1-1 C / Nm ε A 1 C = κ U e = QV = ( C1 + C +...) d C 1 1 1 eq = + +... C eq C 1 C V 1 1 1 R = P = i V i = J A i = + +... R 1 R Σ i = Σ V = in i out closed loop R (...) R + eq = R + R 1 eq dq t t RC i = q = q e q = C V 1 e RC dt Fom 5: 1 at x = v t + v v + at v v = F a = m E = U + K = W nc KE = W net Powe = v P = v F avg t E t f Fiction µn
Pat I. Multiple Choice/Shot Answe (4 points each / points total) no explanation equied, but no patial cedit eithe 1. Two isolated neutal conductos A and B ae connected to the teminals of a V battey that poduces chages on A and B of Q A = -Q B = + mc. What is thei capacitance in mf? (A) 5 (B) 1 (C) (D) (E) 4. Fou ai filled paallel plate capacitos ae constucted as follows: #1 has capacitance C 1, aea A, and gap d; # has capacitance C, aea A and gap d; #3 has capacitance C 3, aea A and gap d; #4 has capacitance C 4, aea A and gap d. Rank thei capacitances, in ode of inceasing C (i.e. smallest fist). (A) C 3, C 1 = C 4, C (B) C 1, C, C 3, C 4 (C) C 4, C 3, C, C 1 (D) C, C 1, C 4, C 3 (E) C, C 1 = C 4, C 3 3. What is the oveall capacitance of this combination of fou 1 µf capacitos? In µf, the oveall capacitance is? (A).4 (B).5 (C) 4. (D).5 (E) 1.5 4. A capacito is chaged by a 5 volt battey stoing enegy U 1. If a 1 volt battey wee used instead, the stoed enegy would by (A) U 1 (B) 4 U 1 (C) U 1 / (D) U 1 / 4 (E) U 1
5. An unchaged 5 µf capacito is in the cicuit shown. Initially the capacito is unchaged and both switches ae open. Switch S 1 is then closed at t=. The capacito's chage Q as a function of time t is (A) Q = 1 mc [1 - e (- t / ms) ] (- t / ms) (B) Q = 1 mc e (C) Q = 1 mc [1 - t/ ms ] (- t /1 ms) (D) Q = 1 mc e (E) Q = 1 mc [1 - e (- t /1 ms) ] 6. (1 points) An isolated ai filled paallel plate capacito has capacitance C, voltage V, and chage Q. If an insulato of dielectic constant 3. is inseted filling the gap between plates, explain in wods what happens to each of the capacito's paametes and why?
7. GOAL Poblem (15 points): Do the "G" and "O" steps of GOAL. You "O" step should include a list of basic physics pinciples you will use to solve the poblem, the equations you will use, and the pocedue you will use to solve the poblem. DO NOT SOLVE the poblem. You and a fiend ae studying fo an exam and the session goes until the ealy moning. About 4 AM you decide to cook some beakfast. Despite being sleepy, things ae going well. The waffles ae cooking and the coffee is peking. The 1-watt waffle ion and the 6- watt coffee make ae plugged into kitchen wall electical outlets. You will also use a kitchen wall outlet fo the 7-watt toaste. You know that if you plug in too many appliances you will oveload the cicuit beake. Should you make some toast now? The kitchen wall outlets ae all pat of the same 11-V cicuit which has a -A cicuit beake (with negligible esistance) to potect the wie caying the lagest cuent fom getting too hot. (The cicuit beake potects those kitchen cicuit wies that have the most cuent fom caying too much cuent. It opens a switch if the cuent though the cicuit beake exceeds its ating. Some homes have fuses to do the same job). You ae tying to figue out how the electical outlets ae connected togethe in a cicuit when you fiend eminds you that when you disconnect the coffeepot, the waffle ion stays on. Now eveything is clea.
8. (15 points) The cicuit chosen has 4 identical light bulbs and an ideal battey with voltage ε. a. Rank the bightness of the bulbs fom bightest to dimmest. Explain you easoning (Be sue to mention any given infomation that you use in you easoning.) b. A wie is now added to the cicuit as shown in figue (b) below i. Does the bightness of bulb C incease, decease, o stay the same? Explain. ii. Does the bightness of bulb A incease decease o stay the same? Explain iii. Does the bightness of bulb D incease, decease, o emain the same? Explain c. The bulbs in the oiginal cicuit ae eplaced by identical esistos with esistance R. Find the cuent though esisto D in tems of the cuent though the battey i battey The cuent dawn fom the battey
9. If R = Ω and ε = 6V, find the cuent supplied by the battey and the powe dissapated by esisto D.