并联电阻的阻值:R= IgRg I?Ig = 0.003×25 0.6?0.003 ≈0.13Ω,改装后电流表的内阻:RA= IgRg I = 0.003×25 0.6 =0.125Ω;答:把G改装成电流表,要并联一个0.13欧姆的电阻R,改装后电流表的内阻RA为0.125欧姆.