16. The figure here shows four arrangements of circular loops of radius r or 2r, centered on vertical axes (perpendicular to the loops) and carrying identical currents in the directions indicated. Rank the arrangements according to the magnitude of the net magnetic field at the dot, midway between the loops on the central axis, greatest first. [ ] 3 (al (d) (3.0) A. d, c,tie of b and a; B. d, a, tie of b and c C. d and b tie, then a and ctie; D. d and a tie, then b and c tie; 17. The graph gives the magnitude B(t) of a uniform magnetic field that exists throughout a conducting loop, with the direction of the field perpendicular to the plane of the loop. For the five regions emf induced in the loop? [ ] (3.0) A bandc; B. a and c and d; C. cand e; D a and c. c 18. The figure shows three situations in which identical circular conducting loops are in uniform magnetic fields that are either increasing (Inc) or decreasing (Dec) in magnitude at identical rates. In each, the dashed line coincides with a diameter. In which case the magnitude of the current induced in the loops is not zero? [ ] Inc Inc Inc De () ( (3.0) A. B. (b); C. (b) and (c); (a) and (b). D 19. The figure shows an emf induced in a coil. Which of the following can describe the current through the coil: (a) constant and rightward, (b) constant and leftward, (c) increasing and rightward, (d) decreasing and rightward, (e) increasing and leftward, (f) decreasing and leftward? [ ] -- lillle (3.0) B. band e; C. d and e; D. a and e. 20. The table lists the number of turns per unit length, current, and cross-sectional area for three solenoids. Rank the solenoids according to the magnetic energy density within them, greatest first. [] Solenoid Turns per Unit Length 2x Current 1 21 Area 2Α, A 64 (3.0) A. , a and b tie, then c; B a and c tie, then b; C b and ctie, then a; D. a, b, then c.