East Los Angeles College Mr. Kiledjian Sample Physics 3 Test for the Multiple Choice section ____ 1. If Q = 16 nC, a = 3.0 m, and b = 4.0 m, what is the magnitude of the electric field at point P? a. b. c. d. e. ____ 33 N/C 31 N/C 24 N/C 19 N/C 13 N/C 2. A uniform linear charge of 2.0 nC/m is distributed along the x axis from x = 0 to x = 3 m. Which of the following integrals is correct for the x component of the electric field at y = 2 m on the y axis? a. b. c. d. e. none of these ____ 3. Two charges of 15 pC and пЂ40 pC are inside a cube with sides that are of 0.40-m length. Determine the net electric flux through the surface of the cube. a. +2.8 N пѓ— m2/C b. пЂ1.1 N пѓ— m2/C c. +1.1 N пѓ— m2/C d. пЂ2.8 N пѓ— m2/C e. пЂ0.47 N пѓ— m2/C ____ 4. Charge of uniform density (80 nC/m3) is distributed throughout a hollow cylindrical region formed by two coaxial cylindrical surfaces of radii 1.0 mm and 3.0 mm. Determine the magnitude of the electric field at a point which is 4.0 mm from the symmetry axis. a. 7.9 N/C b. 10 N/C c. 9.0 N/C d. 8.9 N/C e. 17 N/C ____ 5. A student has made the statement that the electric flux through one half of a Gaussian surface is always equal and opposite to the flux through the other half of the Gaussian surface. This is a. never true. b. never false. c. true whenever enclosed charge is symmetrically located at a center point, or on a center line or centrally placed plane. d. true whenever no charge is enclosed within the Gaussian surface. e. true only when no charge is enclosed within the Gaussian surface. ____ 6. Two identical particles, each with a mass of 2.0 пЃg and a charge of 25 nC, are released simultaneously from rest when the two are 4.0 cm apart. What is the speed of either particle at the instant when the two are separated by 10 cm? a. 7.3 m/s b. 9.8 m/s c. 9.2 m/s d. 6.5 m/s e. 4.6 m/s ____ 7. A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them. When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates. It is then disconnected from the battery and the plates are pulled apart to a separation 2d without discharging them. After the plates are 2d apart, the magnitude of the charge on the plates and the potential difference between them are a. Q0, V0 b. Q0, V0 c. Q0, V0 d. Q0, 2V0 e. 2Q0, 2V0 ____ 8. The plates of a parallel plate capacitor of capacitance are horizontal. Into the gap a slab of dielectric material with is placed, filling the bottom half of the gap between the plates. What is the resulting new capacitance? a. b. c. d. e. ____ 9. By using a compass to measure the magnetic field direction at various points adjacent to a long straight wire, you can show that the wire's magnetic field lines are a. straight lines in space that go from one magnetic charge to another. b. straight lines in space that are parallel to the wire. c. straight lines in space that are perpendicular to the wire. d. circles that have their centers on the wire and lie in planes perpendicular to the wire. e. circles that have the wire lying along a diameter of the circle. ____ 10. At what rate is thermal energy being generated in the 2R-resistor when пЃҐ = 12 V and R = 3.0 пЃ—? a. b. c. d. e. 12 W 24 W 6.0 W 3.0 W 1.5 W ____ 11. The circuit below contains 4 100-W light bulbs. The emf is 110 V. Which light bulb(s) is(are) brightest? a. b. c. d. e. A B C D C and D ____ 12. A long, straight wire (radius = 2.0 mm) carries a current of 2.0 A distributed uniformly over a cross section perpendicular to the axis of the wire. What is the magnitude of the magnetic field at a distance of 1.0 mm from the axis of the wire? a. 0.40 mT b. 0.80 mT c. 0.10 mT d. 0.20 mT e. 0.75 mT ____ 13. A circuit contains two inductors of 6.0 mH inductance in parallel placed in series with an inductor of 8.0 mH inductance. After one of the 6.0 mH inductors burns out, the repairman wants to replace all three inductors with one inductor of equivalent inductance. Assuming inductors combine in series and parallel the same way resistors do, what inductance should he use? a. 3.0 mH b. 3.4 mH c. 4.8 mH d. 11 mH e. 20 mH ____ 14. A loop of wire (resistance = 2.0 mпЃ—) is positioned as shown with respect to a long wire which carries a current. If d = 1.0 cm, D = 6.0 cm, and L = 1.5 m, what current is induced in the loop at an instant when the current in the wire is increasing at a rate of 100 A/s? a. b. c. d. e. 34 mA 30 mA 27 mA 38 mA 0.50 mA ____ 15. As shown below, a square loop of wire of side a moves through a uniform magnetic field of magnitude B perpendicular to the page at constant velocity directed to the right. Judd says that the emf induced in the loop is zero. Roger claims that it has magnitude B . Which one, if either, is correct, and why? a. b. c. d. e. Judd, because the magnetic flux through the loop is constant. Roger, because the magnetic flux through the loop is constant. Judd, because the magnetic flux through the loop is not constant if Roger, because the magnetic flux through the loop is not constant if Roger, because the magnetic flux through the loop is пЃ†B = 0. ____ 16. Determine the rms voltage drop across the resistor in the circuit. a. b. c. d. e. 55 V 77 V 9.9 V 5.5 V 61 V . .

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