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\(A=Pt=75.3.30=6750\)(Wh) = 6,75(kWh)

Error?

1, Góc giữa tia SI còn được gọi là i

\(\Rightarrow i=30^o\)

\(\Rightarrow\)Đáp án 3

2, \(\Rightarrow\)Đáp án 2(chắc zậy)

1. 30^o

^{2. câu thứ 2}

\(R_{tđ}=\dfrac{R_1.R_2}{R_1+R_2}=\dfrac{5.10}{5+10}=\dfrac{10}{3}\left(\Omega\right)\)

\(U=U_1=U_2=15V\)

\(\left\{{}\begin{matrix}I=\dfrac{U}{R_{tđ}}=\dfrac{15}{\dfrac{10}{3}}=4,5\left(A\right)\\I_1=\dfrac{U_1}{R_1}=\dfrac{15}{5}=3\left(A\right)\\I_2=\dfrac{U_2}{R_2}=\dfrac{15}{10}=1,5\left(A\right)\end{matrix}\right.\)

\(P=U.I=15.4,5=67,5\left(W\right)\)

a. \(R=\dfrac{R1.R2}{R1+R2}=\dfrac{5.10}{5+10}=\dfrac{10}{3}\left(\Omega\right)\)

b. \(U=U1=U2=15V\)(R1//R2)

\(\left\{{}\begin{matrix}I1=U1:R1=15:5=3A\\I2=U2:R2=15:10=1,5A\end{matrix}\right.\)

c. \(\left\{{}\begin{matrix}P_m=U_mI_m=15.\left(3+1,5\right)=67,5\\P1=U1.I1=15.3=45\\P2=U2.I2=15.1,5=22,5\end{matrix}\right.\)(W)

mik chon D đúng ko ạ

đúng rồi nhé!

\(\dfrac{1}{R}=\dfrac{1}{R1}+\dfrac{1}{R2}+\dfrac{1}{R3}=\dfrac{1}{4}+\dfrac{1}{10}+\dfrac{1}{15}=\dfrac{5}{12}\Rightarrow R=2,4\left(\Omega\right)\)

\(\Rightarrow I=\dfrac{U}{R}=\dfrac{24}{2,4}=10\left(A\right)\)

\(i=40^o\Leftrightarrow\left\{{}\begin{matrix}i'=40^o\\i+i'=80^o\end{matrix}\right.\)

\(\Rightarrow\) Đáp án 2

80^O

\(R=\rho\dfrac{l}{S}\Rightarrow S=\dfrac{\rho.l}{R}=\dfrac{1,1.10^{-6}.0,8}{4,5}\approx1,9\left(5\right).10^{-7}\left(m^2\right)\)

\(S=\pi\dfrac{d^2}{4}\Rightarrow d=\sqrt{\dfrac{4S}{\pi}}=\sqrt{\dfrac{4.1,9\left(5\right).10^{-7}}{\pi}}\approx5.10^{-4}\left(m\right)=0,5\left(mm\right)\)

\(R=p\dfrac{l}{S}\Rightarrow S=\dfrac{p.l}{R}=\dfrac{1,1.10^{-6}.0,8}{4,5}=1,9.10^{-7}\left(m^2\right)\)

\(S=\pi\dfrac{d^2}{4}\Rightarrow d^2=\dfrac{4S}{\pi}=\dfrac{4.1,9.10^{-7}}{\pi}\simeq2,42.10^{-7}\)

\(\Rightarrow d=\sqrt{2,42.10^{-7}}.10000\simeq0,5\left(mm\right)\)

Chọn D

50 độ

\(i+i'=100^o\Leftrightarrow i=50^o\)

\(\Rightarrow\)Đáp án 3 =))))