Physic Labs

Problem 2

A capacitor C charged to V₀ discharges through resistor R, with q(0)=CV₀. Find q(t) and discharge current i(t). 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=CV0e−t/(RC),iout=(V0/R)e−t/(RC),τ=RCq=CV_0e^{-t/(RC)},\quad i_{\rm out}=(V_0/R)e^{-t/(RC)},\quad\tau=RC
problems.proof.analysis

The boxed expressions answer the parts in order. Signs, conditions of validity, and constants follow the conventions in the statement.