A block in the shape of a rectangular solid has a cross-sectional area of 2.96 cm2 across its width, a front-to-rear length of 12.5 cm, and a resistance of 712 O. The block's material contains 7.57 x 1022 conduction electrons/m3. A potential difference of 44.3 V is maintained between its front and rear faces. (a) If the current density is uniform, what is its magnitude? (b) What is the drift velocity (in meter per second) of the conduction electrons?