помогите пож!!!!!!!!!!!!!!!!!!!!!!

4) Q=I*U*t    t=Q/(I*U)=800/(3*220)=1.2 c
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5) Io=U/R3=6/2=3 A
R12=R1*R2/(R1+R2)=6*12/(6+12)=4 Ом
U12=Io*R12=3*4=12 B
P2=U12/R2=12/12=12 Вт
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6) t=5*60=300 c    T=80-20=60   m=1 кг    c=4200 Дж/кг*С
P=Q/t=c*m*T/t=4200*1*60/300=840 Вт
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