diff --git a/uni/mmme/2xxx/2051_electromechanical_devices/fundamentals.md b/uni/mmme/2xxx/2051_electromechanical_devices/fundamentals.md new file mode 100755 index 0000000..846983b --- /dev/null +++ b/uni/mmme/2xxx/2051_electromechanical_devices/fundamentals.md @@ -0,0 +1,86 @@ +--- +author: Akbar Rahman +date: \today +title: MMME2051 // Electrical Engineering Fundamentals +tags: [ mmme2051 ] +uuid: 412c8cb8-ec0c-4d6f-b899-f1296f4fc639 +--- + +# Across Variable vs Through Variable + +Across variables: + +- Appears across two terminal of an element +- Measured relative to a reference point +- e.g. voltage + +Through variables: + +- Value is same at both terminals of an element +- e.g. current + +# Ohm's Law + +For all components that follow Ohm's law: + +$$V = IR$$ + +where $V$ is voltage across a component, $I$ is current through it, and $R$ is resistance of the component. + +# Impedance vs Resistance + +- Impedance is used when there are energy storage elements to a component. +- Resistance, a special case of impedance, can be used when there is no storage element + +# Kirchhoff's Laws + +## Current + +The sum of current entering a node is 0 + +$$\sum_n I_n = 0$$ + +## Voltage + +The sum of voltage around a closed loop is 0 + +$$\sum_n V_n = 0$$ + +# Energy Storing Elements --- Reactive Elements + +When you apply a voltage to a reactive element, the reactive element will start storing energy. +When the voltage is removed, it will push current until all energy is dissipated. + +There are two types of Reactive Elements + +## Inductors + +A coil of wire wound around a magnetic core, such as iron. + +They have a property, inductance, with SI unit henry and symbol H. + +For an inductor: + +$$V = L\frac{\mathrm{d}I}{\mathrm{d}t}$$ + +where $L$ is the inductance of the coil. + +Energy is stored in the magnetic flux around the coil. + +This creates the behaviour of trying to minimize change in current. + +If you remove the voltage source and open the circuit, the inductor would have a voltage approaching +infinity, causing problems if the energy stored in the inductor is high enough. + +## Capacitor + +For a capacitor: + +$$I = C\frac{\mathrm{d}V}{\mathrm{d}t}$$ + +Energy is stored in the form of electrostatic attraction in the adjacent plates. + +Capacitors try to minimize changes in voltage. + +If a capacitor is shorted, the current through the connecting wires will be extremely high, causing +the wires to heat up.