urp:physelec

Power = watts, current (I) = amps, volts (E or V), resistance (R) = ohms

**Ohm's Law**e = ir- p = ie = i²r

Resistors in series add together

Resistors in parallel: 1/Rt = 1/R₁ + 1/R₂ + …

current in parallel: if have V, compute R for each path. For two paths, R₁ & R₂: I on R₁ = R₁/(R₁+R₂)

Voltage divider: Vout = R₂/(R₁+R₂) * Vtotal, where R₂ is resistor between Vout and ground

Joules = watts * seconds

Q = CV , Q = charge (coulombs, always a positive value), C = capacitance (farads), V = voltage

Parallel plate capacitor

C = epsilon (A/d), A = area, d = distance between plates epsilon = permittivity of the dielectric dielectric constant (over free space) = 8.84 * 10⁻¹² Farads/meter

Electric field E = V/d (volts/meter)

E = sigma/epsilon, sigma = charge density sigma = Q/A

**Coulomb's law**: Find force between two charged objects

F = k * q₁ * q₂ / r² k = 9 * 10⁹ N m²/C² r = distance in meters C = coulombs C = Q/V = Q/Ed = A*epsilon/d

urp/physelec.txt · Last modified: 2021-11-06 by nerf_herder