At which location will the electric field between the two parallel plates of a charged capacitor be the strongest in magnitude?
a. near the positive plate
b. near the negative plate
c. midway between the two plates nearest their center
d. midway between the two plates at their ends
[Ques. 2] A uniform meterstick balances on a fulcrum placed at the 40-cm mark when a weight W is placed at the 20-cm mark. What is the weight of the meterstick?
a. W
c. W/2
b. 2W
d. 0.4W
[Ques. 3] A capacitor is attached across a battery and charged. Then the battery is removed leaving the capacitor charged. The positive lead of the capacitor is then connected to one lead of a previously uncharged identical capacitor, and then the other lead of the charged capacitor is connected to the other lead of the second capacitor. How does the energy E0 stored in the originally charged capacitor compare to the energy Ef stored in the connected capacitors?
a. E0 = 2Ef
c. E0 = 4Ef
b. E0 < Ef
d. E0 = Ef
[Ques. 4] A rod of length L is pivoted about its left end and has a force F applied perpendicular to the other end. The force F is now removed and another force F is applied at the midpoint of the rod. If F is at an angle of 30o with respect to the rod, what is its magnitude if the resulting torque is the same as when F was applied?
a. F
c. 3F
b. 2F
d. 4F
[Ques. 5] Three capacitors have capacitances C1 < C2 < C3 . If these capacitors are connected in series, which of the following is true for the resulting equivalent capacitance?
a. Ceq < C1
c. Ceq = (C1 + C2 + C3)/3
b. Ceq > C3
d. None of the above is always correct.
[Ques. 6] A 3.0-m rod is pivoted about its left end. A force of 10 N is applied perpendicular to the rod at a distance of 1.2 m from the pivot causing a ccw torque, and a force of 5.2 N is applied at the end of the rod 3.0 m from the pivot. The 5.2-N force is at an angle of 30o to the rod and causes a cw torque. What is the net torque about the pivot? (Take ccw as positive.)
a. 18 Nm
c. 4.2 Nm
b. -18 Nm
d. -4.2 Nm
[Ques. 7] Suppose two charges, one positive and one negative, are separated by a distance d. Where can two equipotential surfaces at different potentials intersect in the region near the charges?
a. halfway between the charges if the charges have the same magnitude
b. closer to the smaller negative charge than the larger positive charge if the charges are not equal
c. Equipotential surfaces at different potentials cannot intersect.
d. closer to the smaller positive charge than the larger negative charge if the charges are not equal
[Ques. 8] Two equal magnitude forces are in opposite directions, and their lines of action are separated by distance d. These two forces are applied to a solid disk, which is mounted on a frictionless axle. If d is half the radius r of the disk, which of the following positions for the forces would give the most torque?
a. One force on a line touching the circumference of the disk and the other on a line halfway to the center.
b. One force on a line at a distance d from the center and the other on a line through the center of the disk.
c. One force on a line at a distance d/2 from the center of the disk and the other on a line at a distance d/2 on the opposite side of the center of the disk.
d. Since all the above orientations give the same torque, choose this answer.
[Ques. 9] Suppose two equipotential surfaces are the planes x = 3 m and x = 5 m. If the potential at the x = 3 m surface is 10 V and the potential at the x = 5 m surface is 50 V, what is the magnitude of the electric field between the two surfaces?
a. 40 N/C
c. 15 N/C
b. 20 N/C
d. 10 N/C
[Ques. 10] A bank vault is opened by applying a force of 300 N perpendicular to the plane of the door, 1.2 m from the hinges. Find the torque due to this force about an axis through the hinges.
a. 180 Nm
c. 300 Nm
b. 240 Nm
d. 360 Nm
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