Figure 3.5 shows a single-phase transmission line. Herein, conductor " 1 " is for sending power, and conductors " 2 " and " 3 " are for receiving power. The Geometrical Mean Radius (GMR) of each conductor is \(r^{\prime}\). Calculate the inductance of the line in \(\mathrm{H} / \mathrm{m}\).

1) \(6 \times 10^{-7} \ln \left(\frac{D}{r^{\prime}}ight)\)

2) \(2 \times 10^{-7} \ln \left(\frac{D}{r^{\prime}}ight)\)

3) \(3 \times 10^{-7} \ln \left(\frac{D}{r^{\prime}}ight)\)

4) \(4 \times 10^{-7} \ln \left(\frac{D}{r^{2}}ight)\)

D D 20- D