p đồng = 1,7.10 mũ trừ 8 l = 4m d = 1mm ² π= 3,14 tính R = ? CHÚ Ý S=(d ² : 4 ). π

2 câu trả lời

Đáp án:

Công thức tính điện trở: \(R = \rho \dfrac{l}{S} = \rho \dfrac{l}{{\pi .\dfrac{{{d^2}}}{4}}} = 1,{7.10^{ - 8}}.\dfrac{4}{{3,14.\dfrac{{{{({{10}^{ - 3}})}^2}}}{4}}} = 0,087\Omega \)

Đáp án: đổi 1mm vuông = 10 mũ -6 m vuông

tiết diện của dây đồng là : s=10 mũ -6 bình / 4=2,5 . 10 mũ -3

ta có R=p. (l/s)=1,7 .10 mũ-8 . (4/2,5.10 mũ -3 ) =2.72 . 10 mũ 11

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