Physic Labs

Problem 2

An ideal capacitor of capacitance C=10 μFC=10\,\mu\mathrm F is connected to an ideal source holding voltage V=12 VV=12\,\mathrm V. After electrostatic equilibrium is reached, energy is stored in the electric field between the plates; neglect fringing. (a) Find the first requested quantity. (b) Find the second quantity. (c) Determine the final result and check its units (a) Find the charge on the capacitor. (b) Find its stored electric-field energy. (c) Evaluate both results in SI units.
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Q=(10×10−6)(12)=120 μCQ=(10\times10^{-6})(12)=120\,\mu\mathrm C
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This equation expresses the physical law governing the system. It incorporates the stated constraint rather than treating the relevant quantities as independent.

problems.proof.pitfall. Check the sign convention and physical case carefully; do not use a formula for a different motion or geometry.