A2 Physics 物理 出国英语2.4.1 Resistor Networks MS.pdfVIP

ResistorNetworkAnswers

1.(a)pd=3.6V(1)1

Exampleofanswer;

p.d.=0.24A×15Ω=3.6V

(b)Calculationofpdacrosstheresistor(1)

[6.0–3.6=2.4V]

RecallV=IR(1)

I1calculatedfromtheirpd/4Ω(1)

[correctansweris0.60A.Commonecfis6V/4Ωgives1.5A]3

Exampleofanswer:

I1=2.4V/4.0Ω=0.6A

(c)CalculationofI2fromI1–0.24[0.36A](1)

[allowecfoftheirI1.commonvalue=1.26A]

SubstitutionV=3.6V(1)

R=10Ω(1)3

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2.(a)p.d.across4Ωresistor

1.5(A)×4(Ω)

=6V(1)1

(b)ResistanceR2

CurrentthroughR2=0.5A(1)

6(V)

R2=

0.5(A)

R2=12Ω(1)2

[allowecftheirpdacross4Ω]

(c)ResistanceR1

p.d.acrossR1=12−6−4

=2V(1)

CurrentthroughR1=2A(1)

2(V)

R1==1Ω(1)

2(A)

[allowecfofpdfrom(a)iflessthan12V]

Alternativemethod

Parallelcombination=3Ω(1)

Circuitresistance=12(V)/2(A)=6Ω(1)

R1=6–(3+2)=1Ω(1)