5. (10 points) The resistance of the wire loop shown in the figure between points $A$ and $B$ is $R=15$ Mm. It is known that the distance between these points is $2 M$. Find the resistance $R_{0}$ of one meter of the wire used to make the loop.

![](https://cdn.mathpix.com/cropped/2024_05_06_32f4aa6e8cb387df1c88g-08.jpg?height=457&width=574&top_left_y=497&top_left_x=821)
Answer: $R_{0}=15$ Ohms

Solution. The voltage on the middle vertical crossbars is always zero.

Therefore, the equivalent circuit:

![](https://cdn.mathpix.com/cropped/2024_05_06_32f4aa6e8cb387df1c88g-08.jpg?height=377&width=1082&top_left_y=1353&top_left_x=561)

(3 points)

Its resistance: $\frac{1}{R}=\frac{1}{4 R_{0}}+\frac{1}{2 R_{0}}+\frac{1}{4 R_{0}}=\frac{1}{R_{0}}$.

Final answer: $R_{0}=15$ Ohms.