Electricity
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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:
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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