Question

R₁ mắc song song với R_2, R₃ mắc nối tiếp với R_1,2.

R₁=24Ω

R₂=18Ω

R₃=30Ω

U_AB=36V

a) R_tđ=?

b) I=?

I₁=?

I₂=?

c) Q=?(J), t=30'

Answer 1

a. \(R=R3+\left(\dfrac{R1.R2}{R1+R2}\right)=30+\left(\dfrac{24.18}{24+18}\right)=\dfrac{282}{7}\Omega\)

b. \(I=I12=I3=U:R=36:\dfrac{282}{7}=\dfrac{42}{47}A\left(R3ntR12\right)\)

\(U1=U2=U12=U-U3=36-\left(\dfrac{42}{47}.30\right)=\dfrac{432}{47}\left(R1\backslash\backslash R2\right)\)

\(\Rightarrow\left\{{}\begin{matrix}I1=U1:R1=\dfrac{432}{47}:24=\dfrac{18}{47}A\\I2=U2:R2=\dfrac{432}{47}:18=\dfrac{24}{47}A\end{matrix}\right.\)

c. \(Q=A=UIt=36\cdot\dfrac{42}{47}\cdot30\cdot60\approx57906,4\left(J\right)\)