Question
If the potential due to a point charge is $5.00 \times 10^2 \textrm{ V}$ at a distance of 15.0 m, what are the sign and magnitude of the charge?

$+8.34 \times 10^{-7} \textrm{ C}$

Please note: the video incorrectly shows the wrong exponent for 10. It should be $-7$, not $-6$.

Solution Video

# OpenStax College Physics Solution, Chapter 19, Problem 29 (Problems & Exercises) (0:37) View sample solution

## Calculator Screenshots Video Transcript

This is College Physics Answers with Shaun Dychko. The potential from a point charge is Coulombs constant times the charge divided by the distance from it. And, we can solve this for <i>Q</i> by multiplying both sides by <i>R</i> over <i>K</i>. And then, we get the charge, it's <i>R</i> <i>V</i> over <i>K</i>. So, that's 15 meters times 500 volts divided by Coulomb's constant, 8.99 times ten to the nine Newton meters squared per Coulomb squared. And, that gives a charge of 8.34 times ten to the minus six Coulombs. This is a positive charge because the potential is positive 500 volts.