import numpy as np
import matplotlib.pyplot as plt
U = np.array ([1.6,  4.9, 4. , 6. , 8.7, 8.5, 11.9, 11.6, 13.8, 15.6, 18.7, 20.1, 19. , 23.2])
I = np.array ([0.4,  0.9, 1.1, 1.5, 2. , 2.4, 2.8,  3.1,  3.7,  4.1,  4.5,  4.7,  5.1,  5.6])
plt.plot (I,U,"+")
plt.xlabel ("I (A)")
plt.ylabel ("U (V)")
plt.show()