Physic Labs

Problem 2

A point charge q is in vacuum. Find field and potential at distance r, with potential zero at infinity; kₑ=1/(4πε₀). Use the stated ideal model: quantities are constant or vary only as specified, with no extra drag, losses, or external influences. State a sign convention, keep units consistent, and use a classical approximation only where appropriate. (a) Set up the governing equation from a fundamental law. (b) Solve for the requested quantity under the stated conditions. (c) Check the result using a suitable limit, sign, or unit test, and report both the expression and its physical meaning.
q>0:E outward;q<0:E inwardq>0:\mathbf E\text{ outward};\quad q<0:\mathbf E\text{ inward}
problems.proof.analysis

Check with an independent law, limiting case, or physical sign. This can expose a convention error and confirms that the linked parts use consistent data.