You've decided to protect your house by placing a 5.7-m-tall iron lightning rod next to the house. The top is sharpened to a point and the bottom is in good contact with the ground. From your research, you've learned that lightning bolts can carry up to 45 kA of current and last up to 50 μs. How much charge is delivered by a lightning bolt with these parameters?

A lightning rod or a lightening conductor is a metallic rod installed from the top of the building to a depth in the ground where a wide metallic plate of copper is connected to it.

When the lightening tends to strike near by the rod the rod will attract it and transmit the whole current to the ground which is the sink to the charges. Since the current has a tendency to flow through the path of least resistance it will take the route of the conducting rod (and not the structure) and will go easily to the sink earth.

We know that current is the rate of flow of charge.

Mathematically,

[tex]i=\frac{q}{t}[/tex]...........................(1)

where:

i= current

q= total charge conducted

t= time

Given:

[tex]i=45000A[/tex]

[tex]t=50\times 10^{-6}\,s[/tex]

To determine the charge that is delivered with the above parameters:

Using the eq.(1)

[tex]45000=\frac{q}{50\times 10^{-6}}[/tex]

[tex]q=2.25C[/tex]