When electodes are used to record the electrocardigram, an electrolyte gel is usually put between them and the surface of the skin. this makes it possible for the metal of the electrode to form metallic ions that move into the electrolyte gel. often, after prolonged use, this electrolyte gel begins to dry out and change the characteristics of the electrodes. draw an equivalent circuit for the electrode while the electrolyte gel is fresh. then discuss and illusttrate the way you expect this equivalent circuit to change as the electrolyte gel dries out. in the extreme case where there is no electrolyte gel left, what does the equivalent circuit of the electrode look like? how can this affect the quality of the recorded electrcardiogram?

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?