## Newbie alert : Simple Electrical Theory

 Getting started : defining the Terms ElectroMotive Force (EMF) Current flows because of the force between positive and negative. This is measured in Volts and is what is created to make current flow.  Current The amount of electricity that flows and is measured in Amps. Resistance Resistance is the force within a circuit the opposes current flow and is measured in Ohms. Before a current can flow, it must make a circuit. Conventional current In electrical theory, current flows from positive to negative. Positive is designated (+) and is usually red. Negative or ground is designated (-) and can be black or brown. Activity Use a breadboard to construct a circuit with a battery, led, switch and resistor. Exit ticket Write up the challenge in Google docs Include a digital image in your writeup Save into Google classroom .

## Sub system : the Arduino board

can you identify the following on your board
• the ATMega328 chip
• the 16Mhz clock
• reset switch
• the port you connect to your computer
• digital i/o ports
• analogue i/o ports
• ports where power is available
• external power port
Smarty pants speedy kids might wish to get straight to the "good stuff". If you have an Arduino kit, here is a set of exercises for you to try.

## Sparkfun inventors' guide(PDF)

About the board from the Arduino web site

• ### Topic 4

 Breadboards are one of the most fundamental pieces when learning how to build circuits. They allow you to connect components and test prototype projects before movind on to producing circuit boards. Sparkfun breadboard tutorial

## Ohms law

 This law finds the ratio between voltage and current. This is called the resistance. This animation models how the current (I) in a circuit, the voltage (V) and the resitance (R) in a circuit are related.
• ### Topic 6

 Resistance Skill Be able to determine the value of a resistor from it's colour code.

## Resistor theory

 Resistors in a simple circuit All about circuits Resistors in a series circuit Resistors in a parallel circuit

## Voltage dividers

 A voltage divide is a simple method of controlling current in a circuit.It is a circuit used to create a voltage less than or equal to the input voltage. If there is a constant input voltage, then provided the total resistance remains the same, the same current flows through both resistors. It follows that for Ohms law to be obeyed, the voltage must be split in the ratio of the resistors. eg input voltage = 6 volts     R1 = 1 Ohm     R2 = 2 Ohms Volts in R1 = 2 volts Volts in R2 = 4 volts Changing the resistors in a circuit is a common way to control current for a LED. The point of making a thermometer from a diode is to demonstrate that a materials physical properties can change in response to environmental factors. The diode is set between analog two ports on Arduino and the resistance, hence voltage, changes with the temperature. By comparing the voltages against known standards, we can infer the temperature from the readings. If it bleeds we can kill it,If it produces a voltage, we can measure itif we can measure it, we can infer a value