Question

Answer 1

(R1 nt R2)//R3

a,\(=>Rtd=\dfrac{R3\left(R1+R2\right)}{R3+R1+R2}=\dfrac{10\left(15+25\right)}{10+15+25}=8\left(om\right)\)

b,\(=>Uab=U12=U3=12V=>I3=\dfrac{U3}{R3}=\dfrac{12}{10}=1,2A\)

\(=>I12=I1=I2=\dfrac{U12}{R1+R2}=\dfrac{12}{15+25}=0,3A\)

c,=>(Rx nt R2)//R3

\(=>\dfrac{12}{\dfrac{\left(Rx+R2\right)R3}{Rx+R2+R3}}=\dfrac{12}{7,5}=>Rx=5\left(om\right)\)

Answer 2

a)R12=15+25=40Ω

=> R123=40.10/40+10=8Ω

 Vậy R123=8Ω hay Rab=8Ω

b)I₃=U3/R3=Uab/R3=12/10=1,2A

   I₁=I₂=I₁₂=U12/R12=Uab/R12=12/40=0,3A