Question 16.3: Find the potential energy change for a single electron movin...
Find the potential energy change for a single electron moving from cloud to ground in the thunderstorm of Example 16.2. Express your answer in electron-volts.
ORGANIZE AND PLAN Again Equation 16.4b applies, but now q_{0}is 1 elementary charge e.
\text { Known: } \Delta V=10 MV .
\Delta U=q_{0} \Delta V (Potential energy difference; SI unit: J) (16.4b).
One electron-volt is the energy change when 1 elementary charge moves through a potential difference of 1 volt. Here we have a difference of 10 MV. Therefore, the electron’s energy change is
(10 MV )(1 \text { elementary charge })=10 MeV.
REFLECT It’s easy to work with charge in elementary charges and energy in electron-volts! Had we wanted joules, we would have had to use the conversion 1 eV =1.60 \times 10^{-19} J.