Simple module to calculate electrical resistance in series and parallel circuits.
## Table of Contents
- [Installation](#installation)
- [Usage](#usage)
- [API](#api)
- [Understand the Topic](#understand-the-topic)
- [Development](#development)
- [Contributing](#contributing)
- [Motivation](#motivation)
- [License](#license)
- [Credits](#credits)
## Installation
```sh
$ npm install --save resistance.js
```
## Usage
```js
const resistance = require('resistance.js');
resistance([1, 2, 3], 'series');
//=> 6
resistance([1, 2, 3], 'parallel');
//=> 0.5454545454545455
console.log(resistance([1, 2, 3], 'series') + 'Ω')
// 6Ω
```
## API
### `resistance(circuit, type)`
#### `circuit`
*Type*: `array`
*Description*: Values of resistors associated in your circuit.
*Example*: `[1, 2, 3, 4]`
#### `type`
*Type*: `string`
*Description*: Type of resistors association in your circuit.
*Options*:
- `'series'` or `'s'`: Resistors in series.
- `'parallel'` or `'p'`: Resistors in parallel.
## Understand the Topic
Combinating resistors is very common in many circuits, when we want to reach a
resistance level which only one resistor is not enough.
### Resistors in Series
Let's take the following example:
In an association of series resistors, the equivalent resistor is equal to the
sum of all resistors that make up the association:
```
Req = R1 + R2 + R3 + R4 + ...
```
Also, the voltage in the electric generator is equal to the sum of all the
voltages of resistors:
```
V = V1 + V2 + V3 + V4 + ...
```
The electric current flowing in each resistor is always the same:
```
i = i1 = i2 = i3 = i4 ...
```
And the initial example becomes:
### Resistors in Parallel
Let's take the following example:
In an association of parallel resistors, the equivalent resistor is equal to
the inverse of the sum of all the inverted resistors which make up the
association:
```
1 / Req = (1 / R1) + (1 / R2) + (1 / R3) + (1 / R4) + ...
```
Also, the current in the equivalent resistor is equal to the sum of currents
from the resistors:
```
i = i1 + i2 + i3 + i4 + ...
```
The voltage in the electric generator is always the same:
```
V = V1 = V2 = V3 = V4 = ...
```
And the initial example becomes:
## Development
All the tasks needed for development automation are defined in the
[`package.json`](package.json) *scripts* property and can be run via:
`npm run `
Here is a summary of all the commands:
| **Command** | **Description** |
|---------------|------------------------------------------------------------------------------------------|
| `compile` | Runs the Livescript compiler on the source. |
| `test` | Runs [Mocha](https://mochajs.org/) in BDD mode. |
| `build` | Runs both `compile` and `test` commands. |
## Contributing
Contributions are very welcome! If you'd like to contribute, these
[guidelines](CONTRIBUTING.md) may help you.
## Motivation
I was studying resistors association because of my *Constant Current* discipline
and then decided to put the basics into practice.
## License
[resistance.js](https://github.com/mabrasil/resistance.js) is distributed under
the MIT License, available in this repository. All contributions are assumed to
be also licensed under the MIT License.
## Credits
Some contents used in the [explanation section](#understand-the-topic) were
taken from [here](http://www.infoescola.com/fisica/associacao-de-resistores/).