a,Ta có: \(\dfrac{n_1}{n_2}=\dfrac{U_1}{U_2}\Leftrightarrow U_2=\dfrac{U_1.n_2}{n_1}=\dfrac{220.3000}{2000}=330\left(V\right)\)
b,Ta có: \(\dfrac{n_1}{n_2}=\dfrac{U_1}{U_2}\Leftrightarrow U_1=\dfrac{U_2.n_1}{n_2}=\dfrac{380.2000}{3000}=\dfrac{76}{3}\approx25,33\left(V\right)\)