Conducting Rod Top View 12. A conducting rod of resistance Ris in electrical contact with a frictionless U-shaped rail of width L and negligible resistance. The rod is pulled to the right E a constant velocity v. A magnetic field B is directed into the page., as shown in the figure above. Under these conditions, the electric power dissipated in the rod is P. If the velocity of the rod is doubled, the power dissipated in the rod is (A) Pl4 By P2 cy P (D) 2P (E) 4P 13. Which of the following will increase the magnetic field on the axis of a long solenoid? L. Increasing the current in the solenoid II. Increasing the cross-sectional area of the solenoid III. Inserting an iron core into the solenoid (A) T only (B) 1T only (C) I and III only (D) IT and I only (E) LI, 11, and 111 Wire R 41 y =+4m Wire S 21 y =+2m y = Im Wire T 21 14. Three long wires, R. S, and T, are in the positions and carrying the currents indicated in the figure above. All currents are in the plane of the page and in the direction indicated. What are the magnitude and direction of the magnetic field at the origin? Magnitude Direction (A) Into the page (B) Out of the page 2upd (C) Into the page 2 uol (D) Out of the page (E) Out of the page