99 lines
2.2 KiB
Markdown
Executable File
99 lines
2.2 KiB
Markdown
Executable File
---
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author: Akbar Rahman
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date: \today
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title: MMME2051 // Electrical Engineering Fundamentals
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tags: [ mmme2051 ]
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uuid: 412c8cb8-ec0c-4d6f-b899-f1296f4fc639
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---
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# Across Variable vs Through Variable
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Across variables:
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- Appears across two terminal of an element
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- Measured relative to a reference point
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- e.g. voltage
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Through variables:
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- Value is same at both terminals of an element
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- e.g. current
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# Ohm's Law
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For all components that follow Ohm's law:
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$$V = IR$$
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where $V$ is voltage across a component, $I$ is current through it, and $R$ is resistance of the component.
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# Impedance vs Resistance
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- Impedance is used when there are energy storage elements to a component.
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- Resistance, a special case of impedance, can be used when there is no storage element
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## Admittance
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$$Y \frac1Z$$
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# Kirchhoff's Laws
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## Current
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The sum of current entering a node is 0
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$$\sum_n I_n = 0$$
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## Voltage
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The sum of voltage around a closed loop is 0
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$$\sum_n V_n = 0$$
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# Energy Storing Elements --- Reactive Elements
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When you apply a voltage to a reactive element, the reactive element will start storing energy.
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When the voltage is removed, it will push current until all energy is dissipated.
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There are two types of Reactive Elements
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## Inductors
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A coil of wire wound around a magnetic core, such as iron.
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They have a property, inductance, with SI unit henry and symbol H.
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For an inductor:
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$$V = L\frac{\mathrm{d}I}{\mathrm{d}t}$$
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where $L$ is the inductance of the coil.
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Energy is stored in the magnetic flux around the coil.
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This creates the behaviour of trying to minimize change in current.
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If you remove the voltage source and open the circuit, the inductor would have a voltage approaching
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infinity, causing problems if the energy stored in the inductor is high enough.
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## Capacitor
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For a capacitor:
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$$I = C\frac{\mathrm{d}V}{\mathrm{d}t}$$
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Energy is stored in the form of electrostatic attraction in the adjacent plates.
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Capacitors try to minimize changes in voltage.
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If a capacitor is shorted, the current through the connecting wires will be extremely high, causing
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the wires to heat up.
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# Root Mean Square (RMS)
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$$x_{\text{RMS}} = \sqrt{\frac{x_1^2 + \dots + x_n^2}{n}}$$
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For a sinusoidal wave:
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$$x_\text{RMS} = \frac{A}{\sqrt2}$$
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