Verified answer

Bonjour,

1) U(A) = E

U(D) = O

U(B) = (R₂ + R₃) x E/(R₁ + R₂ + R₃)

U(C) = R₃ x E/(R₁ + R₂ + R₃)

E = 5V   R₁  = 2kΩ    R₂ = 3kΩ   et   R₃ = 5kΩ

U(A) = 5 V

U(B) = 0,8 x E = 4 V

U(C) = 0,5 x E = 2,5 V

2) Re = R₃//R₄ = R₃R₄/(R₃ + R₄)

U(A) = E

U(D) = 0

U(B) = (R₂ + Re) x E/(R₁ + R₂ + Re)

U(C) = Re x E/(R₁ + R₂ + Re)

Re = (5k x20k)/(5k + 20k) = 100.10³/25 = 4 kΩ

U(B) = (3 + 4) x 5/(2 + 3 + 4) = 35/9 = 3,88 V

U(C) = 4 x 5/9 = 20/9 = 2,22 V