What resistance must be included in parallel with the conductor whose resistance is 200 ohms

What resistance must be included in parallel with the conductor whose resistance is 200 ohms so that the total resistance is 40 ohms.

Task data: R1 (resistance of the used conductor) = 200 Ohm; R (required connection resistance) = 40 ohms; parallel connection.

The value of the additional resistance is expressed from the formula: 1 / R = 1 / R1 + 1 / R2, whence 1 / R2 = 1 / R – 1 / R1 = R1 / (R * R1) – R / (R * R1) and R2 = (R1 * R) / (R1 – R).

Let’s calculate: R2 = (200 * 40) / (200 – 40) = 50 Ohm.

Answer: An additional 50 Ohm resistance must be connected to the conductor used.