Cho mạch điện R1 nt R2 có U=9V, R1=30 (ôm), R2=60 (ôm), Rtđ=90 (ôm), I=0,1A. Biết R1 gồm 2 điện trở R11 và R12 ghép song song. Biết R11= 4R12. Tính R11 và R12.

1 câu trả lời

Đáp án:

R12=37,5 ohm

R11=4.37,5=150 ohm

Giải thích các bước giải:

2 điện trở mắc song song có điện trở tương đương là:

R1=(R11.R12)/(R11+R12)

Thay R11=4.R12, ta có:

30=4.R12ˆ2/(5.R12)=0,8.R12 => R12=37,5 ohm

=> R11=4.37,5=150 ohm

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