Answers by visitors named: abdrrahim

problem2 2 (R_2*epsilon)/(R_1+R_2)

problem1 1 (mu_0*I_0*r)/(2*pi*R_1^2) 2 (mu_0*I_0)/(2*pi*r) 3 (mu_0*I_0)/(2*pi*r)*(1-(r^2-R_2^2)/(R_3^2-R_2^2)) 4 0

THANKS ANNE