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The electric current

How to measure current

1) The multimeter and ammeter

The intensity is measured with an ammeter whose symbol is:

Standard symbol for ammeter

The multimeter is a device that can make several kinds of measures including current measurements. We must then use the ammeter mode.

2) How to connect a multimeter in ammeter mode?

- Terminals: We use the COM terminal and a terminal current (mA or A)
- The sense of connection: The electric current must  always go through the terminal intensity and exit through the COM terminal. It is equivalent to say that the COM terminal is closest to the negative terminal and the terminal current closest to the positive terminal of the electric generator.
- The insertion in the circuit: the multimeter is connected in series (The multimeter is inserted between two electric components).

3) How to choose the range of the multimeter in ammeter mode?

Definition: the chosen range on the ammeter corresponds to the greatest current that it can measure.

The selected range should not be smaller than the current because: the measure couldn't be done and the ammeter may be damaged.
The range should not be too high otherwise the measurement may lack of accuracy.

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

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- Basic electrical components
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- 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
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The electric current
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- Direction of electric current in a circuit
- The dangers of electricity
- Current intensity - units
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The Voltage
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- How to measure a voltage ?
- Voltage in open and closed circuits
- Rated current and voltage for a lamp
Alternating voltage and current
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- What are alternating current and voltage ?
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- Oscilloscope
- Oscillogram
- Frequency
- Measuring RMS voltage with a voltmeter
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- Series circuit properties
- Short circuit in  series circuit
- Current law in series - circuits
- Voltage law in series circuits
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- Short circuits in parallel circuits
- Nodes and branches in parallel circuits
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Laws of electricity
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Generating electricity
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- Generating electricity in power plants

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


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