9.
如图所示,电源的电动势\(E\)\(=110 V\),电阻\(R\)\({\,\!}_{1}=21 Ω\),电动机绕线的电阻\(R\)\({\,\!}_{0}=0.5 Ω\),开关\(S_{1}\)始终闭合\(.\)当开关\(S_{2}\)断开时,电阻\(R\)\({\,\!}_{1}\)的电功率是\(525 W\);当开关\(S_{2}\)闭合时,电阻\(R\)\({\,\!}_{1}\)的电功率是\(336 W.\)求:
\((1)\)电源的内电阻;
\((2)\)当开关\(S_{2}\)闭合时流过电源的电流和电动机输出的功率.