Câu 1: 

a) Ta có:

\(\begin{array}{l}
{Z_C} = \dfrac{1}{{\omega C}} = \dfrac{1}{{100\pi .\dfrac{{{{10}^{ - 3}}}}{{6\pi }}}} = 60\Omega \\
Z = \sqrt {{R^2} + Z_C^2}  = \sqrt {{{60}^2} + {{60}^2}}  = 60\sqrt 2 \Omega 
\end{array}\)

b) Ta có: 

\(\begin{array}{l}
{I_0} = \dfrac{{{U_0}}}{Z} = \dfrac{{120\sqrt 2 }}{{60\sqrt 2 }} = 2A\\
\cos \varphi  = \dfrac{R}{Z} = \dfrac{{60}}{{60\sqrt 2 }} = \dfrac{1}{{\sqrt 2 }} \Rightarrow \varphi  = \dfrac{\pi }{4}\\
 \Rightarrow {\varphi _i} = \dfrac{\pi }{4}\left( {rad} \right)\\
 \Rightarrow i = 2\cos \left( {100\pi t + \dfrac{\pi }{4}} \right)
\end{array}\)

Câu 2: 

Đề không rõ ràng