Consider a slab of material containing a volume charge distribution throughout. The slab is of length d in the z direction, and its dimensions in x and y represent a cross-sectional area of A. Free space permittivity exists throughout. The electric field in the slab is given by E = 6.aexp(-az) a, V/m where po is a positive constant. (a) Find the volume charge density p, in the slab. (b) Find the total charge in the slab. (c) Verify your result for part b by evaluating the net outward flux of D through the slab surfaces.

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?