[tex]E_s=\sum\limits^6_{k=1} {E_k} \\ E-identice=>E_s=6E\\r_s=\sum\limits^6_{k=1} {r_k} \\ r-identice=>r_s=6r\\S=1 mm^2=10^{-6}m^2\\R=\rho*\frac{l}{S}=>l=\frac{RS}{\rho}=\frac{6,4*10^{-6}}{4*10^{-7}}= 16 m\\[/tex]
[tex]I_{sc}=\frac{E_s}{r_s}=\frac{6E}{6r}=\frac{E}{r}=>E=I_{sc}r=21r\\ I=\frac{E_s}{R+r_s}<=> 1,8=\frac{6E}{6,4+6r}<=>1,8*6,4+1,8*6r=6*21r<=> 11,52+10,8r=126r<=>11,52=115,2r=>r=\frac{11,52}{115,2}= 0,1\Omega=>r=0,1\Omega[/tex]
[tex]E=21r=21*0,1=2,1V\\E_s=6R=6*2,1=12,6V=>E_s=12,6V\\R_V->+ \infty\\I*R_V=U\\E_s=Ir_s+U<=>12,6=1,8*6*0,1+U<=>12,6-1,08=U=>U=11,52V[/tex]
