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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 received by an electrical device
- Electric power consumption by an electrical device
- Relationship between - Electric power and energy


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The Voltage

How to measure a voltage

   
1) Multimeter and voltmeter

The voltage is measured using a voltmeter whose symbol is:

Standard symbol for voltmeter

The multimeter can measure a current but it can also measure a voltage.
In this case we use the voltmeter mode.
   
2) How to connect a multimeter in voltmeter mode ?

- Terminals: We use the COM terminal and a voltage terminal (V)
- The sense of connection: The COM terminal is closest to the negative terminal and the voltage terminal closest to the positive terminal of the electric generator.
- The insertion in the circuit: The multimeter is connected in parallel (The multimeter is connected to the component's terminals for which we want to know the voltage).
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3) How to choose the range for multimeter in voltmeter mode ?

Definition: The chosen range corresponds to the highest voltage that the voltmeter can measure.

The range used should not be smaller than the measured voltage: the measure couldn't be made and the voltmeter may be damaged.
The range should not be too great otherwise the measurement looses its accuracy.

Method: We must first use the highest range for an approximation of the voltage and then choose the closest (but higher) to obtain a more accurate measurement.
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