Fundamentals of Electricity

#physics#electricity

• Particles with “charge”
  • Subatomic $e^{-},p^{+}$
• Coulomb - $6.24\times 10^{18}$ $e^{-}$ or $p^{+}$
  • $\therefore$ charge on $1e^{-}$ or $p^{+}$
  • $\frac{1}{6.24\times 10^{18}}=1.603\times 10^{-19}C$

$m=\text{mass in kg}$ $q=\text{charge in Coulomb}(C)$ $I=\text{current in Amps}\frac{C}{S}$ or Q/T coulombs per second

Voltage $=\frac{J}{C}$ (joules per coulomb) Voltage is Potential Difference, essentially the difference between two points $P=IV$, Power = Current $\times$ Voltage $V=IR$, Voltage = Current $\times$ Resistance $R=\frac{V}{I}$ Resistance is in the unit $\text{ohm}$ (ohm)

*$\text{ohm}=\frac{m^2\text{kg}}{s^3{A}^2}$ in S.I units, s = seconds, A = area

Resistance limits and controls $I$ in a circuit

• The electrical potential energy of the charge carriers is turned into thermal energy
• A resister is a load, so any load can be modelled by a resistor

By conventional direction: red wire is first, by electron direction, black is first