[填空题]
A galvanometer has an inrq 9qadxvxav lhio6 *340ch/ .ternal resista crdm;9-n;p4trvjy. hxmf:o2 nce of $30\Omega$ and deflects full scale for a $50-\mu A$ current. Describe how to use this galvanometer to make
(a) an ammeter to read currents up to 30 A, $ \times10^{-5 }\;\Omega$
(b) a voltmeter to give a full-scale deflection of 250 V. $ \times10^{6 }\;\Omega$
