Non sembrano difficili.
La prossima volta ricordati di metterli in post differenti.
1)
DPhi = D( N B S cos 0° ) = N S * 1 * DB
E = |- DPhi/Dt| = N S DB/Dt = 10*0.01 *(1 - 0)/10 = 0.01 V = 10^(-2) V;
I = E/R = 0.01/0.5 A = 0.02 A = 2*10^(-2) A
L = R I^2 Dt = 0.5 * 2*10^(-2)^2 * 10 J = 2*10^(-3) J
2)
2) E = - N Dphi/Dt = - 500 *(3*10^(-5) - 1.2*10^(-4))/0.015 V =
= 500 * 0.9 * 10^(-4)/(1.5 * 10^(-2)) V = 500*0.6 * 10^(-2) V = 3 V
3)
DB/Dt = (1.3 - 0)/0.005 T/s = 260 T/s
|E| = DPhi/Dt = S DB/Dt cos 0° = pi r^2 DB/Dt = pi * 0.2^2 * 260 V
Ii = E/R = 0.04 * 260 * pi/3 A = 10.4 pi/3 A = 10.9 A