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Science class online
Chemistry and physics lessons

# Electricity

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

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## The electric current

### Current and units

 1) Effect of current In a series circuit consisting of a variable voltage generator and a bulb, the brightness of the bulb is stronger when the voltage supplied by the generator is higher: the current is therefore also higher The higher current received by an electric component is, the more efficient this component is. 2) Units Current is always denoted with symbol I It is measured in ampere (symbol A) with a device called ammeter Comment: you can also use units derived from ampere as kiloampere, hectoampere the decaampere the deciampere etc. The most widely used of these derived units is milliampere symbol mA (1 A = 1000 mA) Example: If a current of 0.5 amperes flows through a bulb then we can write: I = 0.5 A or I = 500 mA ______________________________________ ______________________________________
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