Réponse :

Bonsoir

Explications :

Loi d'ohm

U (V) = r(ohm) * I (A)

1) U= R *I

U = 20 * 3

U = 60V

2) I = U/R

I = 220/110

I = 2A

3) R = U/I

60mA=0.06A

R = 300/ 0.06

R = 5000 ohm

4) I = U/R

100mV = 0.1 V

I = 0.1/2

I = 0.05A soit 5mA