Problem 72-4    Source:  Problem 2 - page 99 - HALIDAY & RESNICK -    Book: Fundamentos da Física - 8ª edition - Ed. LTC - 2009.

The difference in electrical potential between the Earth and a storm cloud is 1.2 x 10⁹ V. What is the magnitude of the change in electric potential energy of an electron moving from the cloud to Earth?

Solution of the Problem 72-4   

We can solve this problem using the eq. 72-07, reproduced below.

As we know the electron charge q = 1.6 x 10^-19C and the potential difference, then

Carrying out the calculation we find

We can find the answer in eV, as it is enough to divide the value by the electron charge. So