Physic Labs

Problem 2

An ideal capacitor of capacitance C is charged to voltage V₀ and connected at t=0 to a resistor R initially carrying no current. Define discharge current as positive in the discharge direction and v(t) with the initial capacitor polarity; neglect inductance and wire resistance. (a) Establish the discharge differential equation and time constant τ. (b) Find v(t) and current i(t) for t≥0. (c) Calculate heat dissipated from 0 to t and check its limit as t approaches infinity. Use SI units throughout and treat components as ideal exactly as specified. State sign conventions when writing equations and retain units in final results.
Q(∞)=12CV02,the initial stored energy;[RC]=sQ(\infty)=\tfrac12CV_0^2, \text{the initial stored energy}; [RC]=s
problems.proof.analysis

Collect results in the order asked. Dimensions and physical signs provide independent checks; they do not replace the derivation but can expose algebraic errors.