27.43 - CP A uniform rect- Figure 27.43 angular coil of total mass 270 g and dimensions 0.500 m X 1.00 m is oriented with its plane parallel to a uniform 4.00-T magnetic field (Fig. E27.43). T A current of 2.70 A is suddenly 0- 500 m started in the coil. (a) About L which axis (A, or A2) will the coil begin to rotate? Why? (b) Find the initial angular acceleration of the coil just after the current is started. ) 1.00m| -||l|| 27.49 ~ Figure E27.49 shows Figure 52749 a portion of a silver ribbon with z; 2 14.0 mm and y] = 0.24 mm, carrying a current of 140 A in the +xdirecti0n. The ribbon lies in a uniform mag netic field, in the y-direction, with magnitude 0.94 T. Apply the simplified model of the Hall effect presented in Section 27.9. If there are 5.90 X 1028 free elec- trons per cubic meter, find (a) the magnitude of the drift velocity of the electrons in the xdirection; (b) the magnitude and direction of the electric field in the zdirection due to the Hall effect; (c) the Hall emf