Calculate the amount of charge transferred in the lightning strike.
The potential difference between the ground and the atmosphere is $3.0 \times 10^{7}\,\text{V}$. Calculate the average power transferred during the lightning strike, in $\text{GW}$.
A lightning rod is fitted to a tall building so that charge can be carried safely to the ground. The lightning rod is modelled as a uniform cylindrical copper cable with a total length of $95\,\text{m}$ running from the ground to the top of the building, as shown in Fig. 3.1. The resistance of the lightning rod is $9.6\,\Omega$. The resistivity of copper is $1.7 \times 10^{-8}\,\Omega\,\text{m}$. Determine the radius of the lightning rod.
The radius of the copper lightning rod is doubled with no change to its length. State the effect of this change on the resistance of the lightning rod.
A length of $0.12\,\text{m}$ of the lightning rod is removed for testing. A tensile stress of $1.9 \times 10^{6}\,\text{Pa}$ is applied, as shown in Fig. 3.2. The section of the rod follows Hooke’s law. The Young modulus of copper is $1.3 \times 10^{11}\,\text{Pa}$. Calculate the extension of the section.