exam 3 old

1. 1An ion with a charge of +3.2 ´ 10−19 C is in region where a uniform electric field of 5 ´ 104. V/m is perpendicular to a uniform magnetic field of 0.8 T. If its acceleration is zero then its speed must be:

   1. A0 m/s
   2. B1.6 x 10-4 m/s
   3. C4.0 x 104 m/s
   4. D6.3 x 104 m/s
   5. Eany value but 0 m/s
2. 2Two long straight current-carrying parallel wires cross the x axis and carry currents I and 3I in the same direction, as shown. At what value of x is the net magnetic field zero?

   

   1. A0
   2. B1
   3. C3
   4. D5
   5. E7
3. 3A circular loop of wire with a radius of 30 cm lies in the xy plane and carries a current of 3A, clockwise when viewed from a point on the positive z axis. Its magnetic dipole moment is:

   1. A0.85 A*m2, in the positive z direction
   2. B0.85 A*m2, in the negative z direction
   3. C0.25 A*m2, in the positive z direction
   4. D0.25 A*m2, in the negative z direction
   5. E0.25 A*m2, in the xy plane
4. 4The figure belowshows a proton moving at velocity v = (-200 m/s)j toward a longstraight wire with current i = 350 mA. At theinstant shown, the proton's distance from the wire is d = 2.89 cm. What is the magnitude of the magnetic force on theproton due to the current?

   

   1. A2.25e-25N
   2. B1.81e-21N
   3. C4.0e-19N
   4. D2.5e-22N
   5. E7.75e-23N
5. 5Figure (a) shows a length of wire carrying a current i and bent into a circular coil of one turn. In figure (b) the same length of wire has been bent more sharply, to give a coil of two turns, each of half the original radius. If Ba and Bb are the magnitudes of the magnetic fields at the centers of the two coils, what is the ratio Bb/Ba?

   

   1. A4
   2. B2
   3. C1
   4. D1/2
   5. E1/4
6. 6Two long straight wires each carry a current of 12A. One wire lies on the x-axis with its current in the negative x-direction.The other wire lies on the y-axis with its current in the positive y-direction.In the x-y plane, which quadrant (quadrants) has (have) points where themagnetic field is zero?

   

   1. AI
   2. BII
   3. CII and IV
   4. DI and III
   5. EII and III
7. 7Complete the following sentence: When a positively-chargedparticle is released from rest in a region that has a magnetic field directeddue east, the particle will

   1. Aremain at rest
   2. Bbe accelerated due east
   3. Cbe accelerated due north
   4. Dbe accelerated upward
   5. Ebe accelerated downward
8. 8An uncharged capacitor with C = 31.4 μF, a resistor with R = 24.3 kΩ, and a battery with V = 25.7 V are connected in series. What is the charge q (in C) on the capacitor at a time t = 3 time constants, after the switch is closed?

   1. A1.50e-6
   2. B3.31e-4
   3. C2.73e-6
   4. D7.67e-4
   5. E8.97e-4
9. 9In the circuit shown, with theswitch is open the capacitor is completely uncharged. The switch is then closedfor a long time. Then the current through the circuit is 0.2 A. Determine theresistance of the unknown resistor. Hint: Think of the ‘physics’ of thesituation.

   

   1. A10 ohm
   2. B27 ohm
   3. C56 ohm
   4. D61 ohm
   5. E70 ohm
10. 10What is the battery current Ibatwhen the switch in the figure is closed? Hint: After the switch is closed, isthere any potential difference along the wire directly connecting points a and b?

    

    1. A8.0 A
    2. B9.14 A
    3. C1.09 A
    4. D12.5 A
    5. E15. 7 A

Descripción

Test sobre exam 3 old, creado por hank fournier el 17/07/2018.

Autor

hank fournier

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English

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Creado el 17 jul 2018 · actualizado el 17 jul 2018

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