notes/Resources/electricity/formulas.md
2023-04-20 12:25:26 +00:00

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## Ohms Law
*Solve for voltage:*
```latex
\displaystyle V = I*R
```
*Solve for resistance:*
```latex
\displaystyle R = \frac{V}{I}
```
*Solve for current*
```latex
\displaystyle I = \frac{V}{R}
```
## Resistors in Series
```latex
R = R1 + R2 + R3 ...
```
## Resistors in Parallel
```latex
\frac{1}{R} = \frac{1}{R1} + \frac{1}{R2} + \frac{1}{R3} ... \\
\textit{}\\
\textit{For two resistors in parallel:}\\
\textit{}\\
R = \frac{R1 * R2}{R1 + R2}
```
***Tip:***
If resistors of the same value are in parallel the total resistance is a single resistor divided by the amount if resistors.
## Voltage Divider
```latex
V_{out} = V_{in}(\frac{R_{1}}{R_1+R_2})
```
## Thevenins Theorem
States that it is possible to simplify any linear circuit, no matter how complex, to an equivalent circuit with just a single voltage source and series resistance connected to a load.
## Conservation of Charge (First Law)
All current entering a node must also leave that node
```latex
\sum{I_{IN}} = \sum{I_{OUT}}
```
**Example:**
![](Resources/electricity/assets/kirchhoffs-law-1.svg)
For this circuit kirchhoffs law states that:
```latex
\displaystyle i1 = i2 + i3 + i4
```
## Conservation of Energy (Second Law)
All the potential differences around the loop must sum to zero.
```latex
\displaystyle \sum{V} = 0
```
## Capacitors in Series
```latex
\displaystyle \frac{1}{C_{t}} = \frac{1}{C_{1}}+\frac{1}{C_{2}}+\frac{1}{C_{3}} ...
```
## Impedance in a Circuit
```latex
Z = \sqrt{R^2 + X^2} \\
\textit{}\\
X = X_{L} - X_{C} \\
```
## Capacitive Reactance
```latex
\displaystyle X_{c} = \frac{1}{2 \pi fC}
```
## Inductive Reactance
```latex
\displaystyle X_{l} = 2\pi fL
```
## Analog Filters
## Cutoff Frequency for RC Filters
```latex
\displaystyle f_{c} = \frac{1}{2\pi RC}
```
## Cutoff Frequency for RL Filters
```latex
\displaystyle f_{c} = \frac{R}{2\pi L}
```
## Cutoff Frequency for multiple Low Pass Filters
```latex
\displaystyle f_{(-3db)} = f_{c}\sqrt{2^{(\frac{1}{n})}-1}
```
Where $n$ = Number if **identical** filters
## Resonance Frequency for RLC Low Pass Filter
```latex
\displaystyle f_{o} = \frac{1}{2\pi \sqrt{LC}}
```
## Center Frequency with Fc and Fh
```latex
f_{c} = \sqrt{f_{h}*f_{l}}
```
## Filter Response for RC Filters
```latex
V_{out} = V_{in}(\frac{X_c}{\sqrt{R_{1}^2+X_{c}^2}})
```
## Cutoff Frequency $\pi$ Topology Filter
When the two capacitors have the same capacitance, it can be calculated like this:
```latex
\displaystyle f_c = \frac{1}{4\pi\sqrt{LC}}
```
## Angular Frequency ($\omega$)
```latex
\omega = 2\pi f = \frac{2\pi}{T}
```
## RLC Series Response
This is basically Ohms Law:
```latex
\displaystyle V = IZ
```
Where $Z$ is the impedance:
```latex
Z = \sqrt{R^2 + (X_L - X_C)^2}
```
$X_L$ = Reactive Inductance
$X_C$ = Reactive Capacativw
## Current through a transistor
```latex
\displaystyle I_{EQ} = \frac{V_{BB}-{V_{BE}}}{\frac{R_B}{(\beta+1)}+R_E}
```
## Gain Bandwidth Product
```latex
GBP = A_V * f_c
```
```latex
\displaystyle f_c = \frac{GBP}{A_V}
```
## Bandwidth of Multiple OpAmps
Where $n$ = number of stages
and $BW$ = Bandwidth of single op-amp
```latex
BW_E = BW\sqrt{2^\frac{1}{n}-1}
```
## Power lost in a Resistor
```latex
P = IV = I^2R = \frac{V^2}{R}
```