# Physics

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Three conducting straight wires (though insulated from each other) are each 2 m long. They are electrically connected to each other only at their ends points A and B. AB = 2 meter.

The wires are cylindrical. One is made of copper, one of aluminum and one of iron. Their radii are 2, 3 and 4 mm, respectively.

a) What is the ohmic resistance between point A and B? Express your answer in Ohms. (you might need to look up the resistivity of these elements).

We now attach at B a straight copper wire which is in electrical contact with the 3 wires at B. This 2nd copper wire is identical to the one between A and B. It runs from B to C. The distance AC is 4 m.

(b) What is the ohmic resistance between A and C? Express your answer in Ohms.

We now turn AC into a near perfect circle. A is very close to C but it is not touching C.

(c)

What is the ohmic resistance between A and C now? Express your answer in Ohms.

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