According to Weiss's law of excitation of tissue, the strength S of an electric current is related to the time t the current takes to excite tissue by the formula S(t) = (t > 0) + b where a and b are positive constants. (a) Evaluate lim s(t) and interpret your result. lim S(t) t-0+ %3D As the time taken to excite the tissue is made shorter and shorter, the strength of the electric current gets stronger and stronger. As the time taken to excite the tissue is made longer and longer, the strength of the electric current gets weaker and weaker. (b) Evaluate lim s(t) and interpret your result. (Note: the limit in part (b) is called the threshold strength of the current.) t+ 00 lim s(t) =