$\begin{array}{|c|c|c|}\hline \text{Lần đo}&\text{HĐT}\,\,\,U(V)&\text{CĐDĐ}\,\,\,I(A)&\dfrac{U}{I}\\\hline B&1,5&0,3&\dfrac{1,5}{0,3}=5\\\hline C&3,0&0,6&\dfrac{3,0}{0,6}=5\\\hline D&4,5&0,9&\dfrac{4,5}{0,9}=5\\\hline E&6,0&1,2&\dfrac{6,0}{1,2}=5\\\hline\end{array}$