The resistivity of iron at 20°C is 9.71 × 108 The resistivity of silver at 20°C is 1.59 × 108 The resistivity of Glass at 20°C is 1.10 × 109 The resistivity of nichrome at 20°C is 100 × 108 Hence silver is the least resistive material in the given option.
While estimating the overhead lines, the first and last pole is always earth connected and after every 3rd electrical pole, the fourth pole is earthed. Therefore, the approximate number of required ground set = 4
EXAMIANS
