# Electricity

Learning physics and chemistry easily and freely - Science for elementary school, middle school and high school

Free online electricity lessons for elementary school,  middle school and high school.

## How to determine a resistance ?

1) Measuring resistance with an ohmmeter

A multimeter can be used to measure a resistance. It must then be used by selecting the ohmmeter mode.

Using the multimeter as ohmmeter:
- Choice of terminals: the COM terminal and the terminal with symbol Ω must be selected.
- Connection: the multimeter is connected directly to the resistor's terminals (when this one is not included in an electrical circuit )
- The range: It is selected using the same method as for measurements of voltage and current. The highest range must be selected first and then it is decreased until to reach the smallest among the ranges superiors to the measured resistance.

2) Determining a resistance using the color code

A resistance can be determined using colored rings which have assigned values ​​according to a color code.

 Science class Chemistry Electricity Optics Mechanics Electricity lessons Electrical components -Two-terminal electronic components - Basic electrical components - Diodes - What's a resistor ? - How to determine a resistor value ? - Resistors effects in circuits - How to use a resistor ? - Characteristic curve of a resistor How to build simple circuits and draw diagrams - How to build a basic electrical circuit - How to draw diagrams of electric circuits The electric current - Conductors and insulators - Direction of electric current in a circuit - The dangers of electricity - Current intensity - units how to measure current ? The Voltage - The voltage and its units - How to measure a voltage ? - Voltage in open and closed circuits - Rated current and voltage for a lamp Alternating voltage and current - Alternating currents effects on led - What are alternating current and voltage ? - Periodic alternating voltage and its properties - Oscilloscope - Oscillogram - Frequency - Measuring RMS voltage with a voltmeter Serie circuits - What's a serie circuit ? - Series circuit properties - Short circuit in  series circuit - Current law in series - circuits - Voltage law in series circuits Parallel circuits - What's a parallel circuit ? - Some parallel circuits properties - Short circuits in parallel circuits - Nodes and branches in parallel circuits - Current laws in parallel circuits - Voltage laws in parallel circuits Laws of electricity - Ohm's law - Current laws in series circuits - Voltage laws in series circuits - Current laws in parallel circuits - Voltage laws in parallel circuits Generating electricity - Voltage for coil wires What is an alternator ? - Alternating currents and voltages - Generating electricity in power plants Electric power and energy - Electric power and power rating - Electric power consumption by an electrical device - Relationship between - Electric power and energy