Question

Answer 1

1: \(\Rightarrow\dfrac{U1}{U2}=\dfrac{I1}{I2}\Leftrightarrow\dfrac{12}{48}=\dfrac{0,5}{I2}\Rightarrow I2=2A\)

2.\(\Rightarrow\dfrac{U1}{U2}=\dfrac{I1}{I2}\Leftrightarrow\dfrac{24}{U2}=\dfrac{5}{10}\Rightarrow U2=48V\)

3.a,\(\Rightarrow I1=Im=\dfrac{U}{R1}=\dfrac{12}{10}=1,2A\)

b,\(\Rightarrow R2=\dfrac{U}{I2}=\dfrac{12}{0,5I1}=\dfrac{12}{0,5.1,2}=20\Omega\)

c4.R1 nt R2

a,\(\Rightarrow Rtd=R1+R2=30\Omega\)

b, \(Rtd'>Rtd\left(45>30\right)\Rightarrow R1ntR2ntR3\)

\(\Rightarrow R3=Rtd'-Rtd=45-30=15\Omega\)

5. R1 nt R2

a,\(\Rightarrow Ia=I1=I2=Im=\dfrac{Uv2}{R2}=\dfrac{3}{15}=0,2A\)

b,\(\Rightarrow Uab=Im.\left(R1+R2\right)=0,2\left(5+15\right)=4V\)

c6: R1//R2

a,\(\Rightarrow Rtd=\dfrac{R1R2}{R1+R2}=6\Omega\)

b,\(\Rightarrow Ia=\dfrac{Uv}{Rtd}=\dfrac{12}{6}=2A\)

\(\Rightarrow Ia1=\dfrac{Uv}{R1}=\dfrac{12}{15}=0,8A\Rightarrow Ia2=\dfrac{Uv}{R2}=1,2A\)

 

Answer 2

c7: 18V-0,8A : 18V: hdt dinh muc cua den khi hoat dong bth

-0,8A: cuong do dong dien dinh muc cua den khi hoat dong bth

b, R1//R2 vi 2 den giong nhau \(\Rightarrow R1=R2=\dfrac{Ud^2}{Pd}=\dfrac{18^2}{Id.Ud}=\dfrac{18^2}{18.0,8}=22,5\Omega\)

\(\Rightarrow I1=I2=\dfrac{9}{\dfrac{R1.R2}{R1+R2}}=\dfrac{9}{\dfrac{R1^2}{2R1}}=0,8A=Idm\)

=>2 bong den sang bth

b8. R1//R2

\(I1+I2=6A\Leftrightarrow2I2=I2=6\Rightarrow I2=2A\Rightarrow I1=4A\)

\(\Rightarrow R1=\dfrac{U}{I1}=\dfrac{42}{4}=10,5\Omega\Rightarrow R2=\dfrac{U}{I2}=21\Omega\)

b9 \(K1\) dong \(\Rightarrow Ia=I1=2,4A\Rightarrow R1=\dfrac{48}{2,4}=20\Omega\)

K2 dong \(\Rightarrow Ia=I2=5A\Rightarrow R2=\dfrac{48}{5}=9,6\Omega\)

k1,k2 dong =>R1//R2 

\(\Rightarrow Ia=\dfrac{48}{\dfrac{R1R2}{R1+R2}}=7,4A\)

 

Answer 3

c10: \(\Rightarrow U1=I1R1=24.2,2=52,8V\)

\(\Rightarrow U2=I2R2=30.1,8=54V>U1\)

=> R1//R2 thi phai chon Umax=U1=52,8V

c11 R1 nt( R2//R3)

b,\(\Rightarrow Rtd=R1+\dfrac{R2R3}{R2+R3}=18+\dfrac{20.30}{20+30}=30\Omega\)

c,\(\Rightarrow I1=I23=\dfrac{U}{Rtd}=\dfrac{60}{30}=2A\Rightarrow U23=U2=U3=I23.\left(\dfrac{R2R3}{R2+R3}\right)=24V\Rightarrow I2=\dfrac{U2}{R2}=\dfrac{24}{30}=0,8A=>I3=I1-I2=1,2A\)

C12;

a,\(\Rightarrow V=Sl\Rightarrow l=\dfrac{V}{S}=\dfrac{\dfrac{m}{D}}{S}=\dfrac{\dfrac{0,5}{8900}}{10^{-6}}=56m\)

b,\(\Rightarrow R=\dfrac{pl}{S}=\dfrac{1,7.10^{-8}.56}{10^{-6}}=0,952\Omega\)