Circle the closest answer and Bubble in questions 1-15 ON YOUR BUBBLE SHEET!0. Bubble in your name, your correct Student ID number onto your bubble sheet. If you leave your ID number blank, do not bubble it in, or bubble it in incorrectly we will deduct a point from your exam score. If you are not certain about your number, please see an instructor. To ensure accurate grading, bubble your Exam version number (0001) in the “1234” column on the bubble sheet.1. A circuit with a battery, two identical lightbulbs and a switch is shown to the right. Initially the switch is open as shown to the right. If the switch is closed, what happens to the current that passes through the circuits at points P and Q?A) Both stay the sameB) Both increaseC) IP stays the same, IQ increasesD) IP increases, IQ stays the sameE) IP decreases, IQ stays the same 2. Two capacitors (2 µF and 4 µF) are shown on the right connected to a 6 V battery. What is the potential difference across the 2 µF capacitor? (Assume it is a long time after they were connected to the battery.)A) 6 VB) 4 VC) 3 VD) 2 VE) 1 VSpring 2012 E2.4 V1 First MidtermSwitchQ6 V2 µF4 µFP3. A negative charge, -q, is placed between charged plates as shown in the figure to the right. The charge starts at an initial position near the negative plate and is moved to a final position close to the positive plate. Did the electric potential energy, U, increase/decrease? Did the potential at the location of the negative charge,V, increase/decrease?A) U and V increasedB) U and V decreasedC) U increased and V decreasedD) U decreased and V increased4. Suppose a region of space has a uniform electric field directed downwards as shown. Three points are labeled A, B, and C. Points B and C are on the same horizontal line. Which statement is correct?A) The voltage at all three locations is the sameB) The voltage at points B and C are equal, and the voltage at point B is higher than the voltage at point AC) The voltage at points B and C are equal and the voltage at point B is lower than the voltage at point AD) The voltage at point A is the highest, the voltage at point C is the second highest, and the voltage at point B is the lowestE) None of the above 5. Two metal conducting spheres are connected by an ideal wire. The combined system has a total positive charge of +15 C, and sphere 1 has a radius of 10 cm while sphere 2 has a radius of 20 cm. Assume that the spheres are far apart, and that they have been connected for a long time. What can you say about the charge on each sphere, Q1 and Q2?A) Q1=+7.5 C, Q2=+7.5 CB) Q1=+10 C, Q2=+5 CC) Q1=+5 C, Q2=+10 CD) Q1=+3 C, Q2=+12 CE) Q1=+12 C, Q2=+3 C+++++-----E-qinitialfinal!"!#!$!Spring 2012 E2.5 V1 First Midterm10cmSphere 220cmSphere 1wireday=?6. An electron (mass =9x10-31 kg), charge =1.6x10-19 C) is initially moving along the x-axis with speed v. It travels between two parallel plates that have a potential difference of 5x10-6 V and are separated by a distance d=0.2 m. The electron is deflected in the y direction. What is the y-component of its acceleration while it is in the region between the plates? (Do not include gravity.)A) 4.44x106 m/s2B) 2.25x10-7 m/sC) 8.89x105 m/s2 D) 1.78x105 m/s2E) 5.0x10-6 m/s27. In class you saw a pickle light up like a light bulb. It was plugged into the 120 V outlet and was as bright as 30 W lightbulb, so let’s assume that the pickle dissipated 30 W of power. What is the approximate resistance of the pickle?A) 960 Ω B) 480 Ω C) 4 Ω D) 0.250 Ω E) 2.083x10-3 Ω8. Each resistor in the circuit shown below has a resistance of R. What is the equivalent resistance of the circuit (that is, the total resistance between points A and B)?A) 4R/3B) 3RC) 3R/2D) 2RE) 2R/3!!"!"!""!#!Spring 2012 E2.6 V1 First Midtermxyay=??9. The circuit on the right contains a 12 V battery and three 1 Ω resistors. What is the total power dissipated in this circuit? Assume an ideal battery and perfect wires.A) 432 WB) 144 WC) 48 WD) 96 WE) None of the above10. A parallel plate capacitor with adjustable plate separation d and adjustable area A is connected to a battery. The capacitor is fully charged to Q Coulombs and a potential difference of V Volts. Which of the following statements are true?I. With the capacitor connected to the battery, increasing the separation d will have no effect on Q.II. With the capacitor connected to the battery, increasing the area A will increase U.III. After being disconnected from the battery, increasing d increases VA) I, II and IIIB) II onlyC) II and IIID) I and IIE) none of the above11. A parallel-plate capacitor consists of two charged metal plates and a neutral plastic block with dielectric constant κ (κ>1), as shown below. How does the magnitude of the E-field inside the plastic, EBlock, compare with the magnitude of the E-field in the air between the plates, EAir?A) EBlock=0, EAir > 0 B) 0 < EBlock < EAirC) 0< EBlock = EAirD) 0< EAir < EBlockE) 0 = EAir = EBlock!Spring 2012 E2.7 V1 First Midterm12 V1 Ω1 Ω1 Ωmetal plate with charge= -Qplastic block, κ>1ΕΑir=?ΕBlock=?metal plate with charge= +QThe next two questions refer to the diagram shown below. Four identical light bulbs are connected to a battery as shown below. Assume an ideal battery and perfect wires.12. How does the brightness of Bulb A compare to Bulb C?A) Bulb A is brighterB) Bulb C is brighterC) They are equally brightD) Impossible to tell13. Which is the brightest bulb?A) Bulb AB) Bulb BC) Bulb CD) Bulb DE) There is a tie for the brightestSpring 2012 E2.8 V1 First MidtermVABCD14. A wire with resistance R1 is cut into four equal length pieces and a new resistor R2 is made by pressing the four pieces side by side as shown!What is the ratio R2 / R1 ?A) 4 B) 1/4 C) 1/16 D) 1/64 E) 1615. See the circuit diagram shown below. Which one of the following equations is correct, given the choice of current directions? (Only one is correct.)A) V1 – I2R2 + I1R1 = 0 B) V2 – I2R2 – I3R3 = 0 C) V1 + V2+ I1R1 + I3R3 = 0 D) V1 – V2 – I1R1 – I3R3 = 0 E) V1 + V2 - I1R1 – I3R3 = 0!!"#!!$%!!$#!!&%!!&#!!!!"%!!"'!Spring 2012 E2.9 V1 First MidtermR3I1FIRST Long Answer Problem (13 points):Consider the equipotential contours shown below. Four points A, B, C, and D are indicated.1. (4 points) On the diagram above, draw arrows at Point A and Point D indicating the direction of the Electric Field at A and D.
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