Question

Answer 1

\(R_{23}=\dfrac{R_2.R_3}{R_2+R_3}=\dfrac{10.5}{10+5}=\dfrac{10}{3}\left(\Omega\right)\)

\(R_{tđ}=R_1+R_{23}=15+\dfrac{10}{3}=\dfrac{55}{3}\left(\Omega\right)\)

Do mắc nối tiếp nên \(I=I_1=I_{23}=\dfrac{U}{R_{tđ}}=\dfrac{12}{\dfrac{55}{3}}=\dfrac{36}{55}\left(A\right)\)

\(U_1=I_1.R_1=\dfrac{36}{55}.15=\dfrac{108}{11}\left(V\right)\)

Do mắc song song nên \(U_{23}=U_2=U_3=I_{23}.R_{23}=\dfrac{10}{3}.\dfrac{36}{55}=\dfrac{24}{11}\left(V\right)\)

\(Q_{tỏa_2}=A_2=\dfrac{U_2^2}{R_2}.t=\dfrac{\left(\dfrac{24}{11}\right)^2}{10}.30.60\approx857\left(J\right)\)

\(P_1=U_1.I_1=\dfrac{108}{11}.\dfrac{36}{55}=\dfrac{3888}{605}\left(W\right)\)

\(A_1=P_1.t=\dfrac{3888}{605}.30.60\approx11568\left(J\right)\)