[填空题]
Suppose a current is 61hwbm*ov ib: k77axt x)y o+jm6 -qsr; cvth(given by the equation $I\,=\,1.80sin210t$, where I is in amperes and t in seconds.
(a) What is the frequency? Hz
(b) What is the rms value of the current? A
(c) If this is the current through a $42-\Omega$ resistor, write the equation that describes the voltage as a function of time. ( sin 210 t)V
