12. Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of inside diameter 1 mm and outside diameter 2 mm. The ratio of their resistance, RA/RB, is:________.

詳解 (共 1 筆)

助人為本

詳解 #7415324

2026/06/21

所以同材質，同長度的時候

圓的面積為pi*r^2

所以因為電阻和面積成反比

11. To alleviate the traffic congestion between two cities such as Paris and Seattle, engineers have proposed building a rail tunnel along a chord line connecting the cities. A train, unpropelled by any engine and starting from rest, would fall through the first half of the tunnel and then move up the second half. Assuming Earth is a uniform sphere and ignoring air drag and friction, find the city-to-city travel time. (Use 6.37 ×10⁶ m for earth radius and 5.98 × 10²⁴ kg for earth mass) (10分)

12. Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1 mm. Conductor B is a hollow tube of inside diameter 1 mm and outside diameter 2 mm. The ratio of their resistance, RA/RB, is:________.

詳解 (共 1 筆)

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