asdas asked in 科學工程學 · 8 years ago

電路學名詞小問題?

As a design engineer, you are asked to design a lighting system consisting of a 70-W power supply and two lightbulbs as shown in Fig. 2.124. You must select the two bulbs from the following three available bulbs.

R1 = 80Ω, cost = $0.60 (standard size)

R2 = 90Ω, cost = $0.90 (standard size)

R3 = 100 Ω, cost = $0.75 (nonstandard size)

The system should be designed for minimum cost such that I = 1.2 A ± 5 percent.

以上為原題目

我想問的問題是

R1 = 80Ω, cost = $0.60 (standard size)

R2 = 90Ω, cost = $0.90 (standard size)

R3 = 100 Ω, cost = $0.75 (nonstandard size)

的standard size和nonstandard size對做題目時有啥影響?

2 Answers

Rating
  • 麻辣
    Lv 7
    8 years ago
    Favorite Answer

    As a design engineer, you are asked to design a lighting system consisting of a 70-W power supply and two lightbulbs as shown in Fig. 2.124. You must select the two bulbs from the following three available bulbs.

    R1 = 80Ω, cost = $0.60 (standard size)

    R2 = 90Ω, cost = $0.90 (standard size)

    R3 = 100 Ω, cost = $0.75 (nonstandard size)

    The system should be designed for minimum cost such that I = 1.2 A ± 5 percent. 以上為原題目.我想問的問題是

    R1 = 80Ω, cost = $0.60 (standard size)

    R2 = 90Ω, cost = $0.90 (standard size)

    R3 = 100 Ω, cost = $0.75 (nonstandard size)

    的standard size和nonstandard size對做題目時有啥影響?

    ans: 沒有影響.目標=最便宜

    w=I^2*R=1.2^2*80=115.2Watts

    非常接近70watts

    所以選用80Ω最便宜

  • Anonymous
    7 years ago

    我每次都是去這里看的哦, http://lvmiss.com/

    产兲唅刲

Still have questions? Get your answers by asking now.