Question

How much electrical potential energy does a proton lose as it falls through a
potential drop of 5kV?

Answer 1

Explanations & Calculations

• Energy variation/work done of a charge ($q$ ) moves through a voltage difference ($\small \Delta V$ ) is given by

$\qquad\qquad \begin{aligned} \small W = q\Delta V \end{aligned}$

• This energy is either stored or released according to the moving direction.
• Charge of a proton is the same to that of an electron but opposite in polarity.
• q _proton = $\small +1.6 \times 10^{-19} C$

• Therefore, potential energy drop of the proton is,

$\qquad\qquad \begin{aligned} \small W&= \small 1.6 \times 10^{-19} C \times(5\times 10^3 V)\\ &= \small \bold{8\times10^{-16} J} \end{aligned}$