\(MCD:R_1ntR_2ntR_3\)

Điện trở tương đương:

\(R_{td}=\dfrac{U_{AB}}{I_{AB}}=\dfrac{24}{0,4}=60\Omega\)

Theo đề bài, ta có: \(R_1=R_2=R_3\)

\(\Rightarrow R_{td}=R_1+R_2+R_3=3R_1\)

\(\Rightarrow R_1=\dfrac{R_{td}}{3}=\dfrac{60}{3}=20\Omega\)

\(MCD:R_1//R_2\)

\(\Rightarrow U=U_1=U_2=I_1\cdot R_1=10\cdot1,2=12V\)

Ta có: \(I=I_1+I_2\)

\(\Rightarrow I_2=I-I_1=1,8-1,2=0,6A\)

\(MCD:R_1ntR_2\)

\(\Rightarrow R_{td}=\dfrac{U}{I}=\dfrac{6}{0,5}=12\Omega\)

Ta có: \(R_{td}=R_1+R_2\)

\(\Rightarrow R_2=R_{td}-R_1=12-5=7\Omega\)

à =))

\(MCD:\left(R_1ntR_2\right)//\left(R_3ntR_4\right)\)

\(\Rightarrow R_{td}=\dfrac{R_{12}\cdot R_{34}}{R_{12}+R_{34}}=\dfrac{\left(9+15\right)\cdot\left(10+18\right)}{9+15+10+18}=\dfrac{168}{13}\Omega\)

Ta có: \(U_{AB}=U_{12}=U_{23}=60V\)

\(\Rightarrow\left\{{}\begin{matrix}I_{12}=I_1=I_2=\dfrac{U_{12}}{R_{12}}=\dfrac{60}{9+15}=2,5A\\I_{34}=I_3=I_4=\dfrac{U_{34}}{R_{34}}=\dfrac{60}{10+18}=\dfrac{15}{7}A\end{matrix}\right.\)

Ta có: \(U_{MN}=U_{AN}+U_{AM}\)

\(\Leftrightarrow U_{MN}=-U_3+U_1=-\left(10\cdot\dfrac{15}{7}\right)+\left(9\cdot2,5\right)=\dfrac{15}{14}V\)

\(C:\)

\(2m^2=20000cm^2\)

\(8dm^2=8000cm^2\)

\(5dm^2=50000mm^2\)

\(2,5cm^2=2500mm^2\)

\(150cm^2=150000mm^2\)

\(4cm^2=4\cdot10^{-4}m^2\)

\(30dm^2=0,03m^2\)

\(D:\)

\(5kV=5000V\)

\(360V=0,36kV\)

\(200mV=0,2V\)

\(12,8V=12800mV\)

\(2,5A=2500mA\)

\(500mA=0,5A\)

\(90mA=0,09A\)

\(A:\)

\(12km=12000m\)

\(3,5km=3500m\)

\(500m=0,5km\)

\(2,5m=2,5\cdot10^{-3}km\)

\(400cm=4m\)

\(90cm=0,9m\)

\(750mm=0,75m\)

\(6dm=0,6m\)

\(8cm=8\cdot10^{-5}km\)

\(1,5km=1500m\)

\(B:\)

\(1,5h=90p\)

\(2h20p=140p\)

\(1h30p=5400s\)

\(15p=900s\)

\(30p=1800s\)

\(600s=\dfrac{1}{6}h\)

\(10p20s=620s\)

\(30s=\dfrac{1}{120}h\)

\(25p=1500s\)

\(1h10p=4200s\)

Exercise 5: Complete using in, on, or at
1. There are lots of people ...........in............... the restaurant.
2. The people who live ...........at............... number 44 are away on holiday.
3. You should go to the Louvre when you're ...............in........... Paris.
4. Gorillas live ........on.................. forests in Africa and eat fruit.
5. What does that sign ............in.............. the wall say?
6. What did Ethan say ...............in........... his letter?
7. Have you heard of the strange statues .........on................. Easter Island?
8. Do you really want to spend the whole day ...........on............... the beach?
9. We spent the whole day ..........at................ the seaside.
10. Patty is .........on................. holiday until next week.
11. Meet me ..............at............ the café .........in................. Fleet Street.
12. Tom is holding a shiny gold coin ..............on............ his hand.
13. Today Helen had to go to school ..........on................ foot.
14. Fred lives ..........at................ 38 Franklin Road.
15. My brother is still ............at.............. school and my sister is ...................on....... the bus coming home.
16. Will you pay by credit card or ...............in........... cash?
17. Is your favorite Mexican dish ..............on............ the menu?
18. This is my class photo. I’m the one ...........in............... the middle of the second row.