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Free online electricity lessons for elementary school,  middle school and high school.
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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 received by an electrical device
- Electric power consumption by an electrical device
- Relationship between - Electric power and energy


Electrical components

How to use a resistor ?

If a resistor is placed in an electric circuit, it may produce two kind of phenomena:

- The resistor has an influence on the electric current (the higher the resistance is, the lower the current is).
This influence on the current is used in many electrical appliances and electronics to modify the electric current. They serve to protect electric components that do not support too high currents.
In this case the resistor serves to regulate the electric current.

- A resistor traveled by an electric current gives rise to the Joule effect.
By definition the Joule effect is the transformation of electrical energy received by the resistor into thermal energy.
A resistor traversed by a current starts to heat up. This can be annoying and unwanted in some cases but it can be harnessed to produce heat. Thus we find resistors in electric ovens, electric heaters, hair dryers, irons etc.