Name: counting significant figures in measurements
Uploaded: 2023-09-22T11:49:39.000Z
Duration: 1 min 44 s
Channel: JoVE

La certitude de la mesure dépend de deux facteurs : le nombre de chiffres dans la mesure et la précision de l’instrument utilisé.
Dans une grandeur mesurée, tous les chiffres, y compris le dernier chiffre incertain, sont appelés chiffres significatifs - et peuvent être déterminés à l’aide de règles spécifiques.
Tous les chiffres non nuls et tous les zéros captifs - qui se trouvent entre deux chiffres non nuls - sont significatifs. Par exemple, 28 a deux chiffres significatifs, tandis que 26,25 en a quatre et 208 en a trois.
Les zéros non significatifs ne sont jamais significatifs, car ils ne font que localiser la virgule. Par exemple, 0,00208 a trois chiffres significatifs. De telles quantités peuvent être exprimées à l’aide de notations exponentielles. Ainsi, 0,00208 peut s’écrire 2,08 × 10−3.
Les zéros à droite ne sont significatifs que dans les nombres au format décimal. 2200 a deux zéros à droite et deux chiffres significatifs, tandis que 2200.0 et 2200.1 ont tous deux 5 chiffres significatifs.
Pour les quantités sans virgules, la signification des zéros à droite devient ambiguë. Ainsi, 2200 peut être écrit 2,2 × 103 avec deux chiffres significatifs ou 2,20 x 103 avec trois chiffres significatifs.

règles des chiffres significatifs

Rules of Significant Figures

Dans toute mesure, la précision de l'outil de mesure est un facteur essentiel. Par exemple, une règle ordinaire peut mesurer une longueur au millimètre le plus proche ; en revanche, un pied à coulisse peut mesurer une longueur au centième de millimètre le plus proche. Par conséquent, le pied à coulisse est un outil de mesure plus précis car il peut mesurer des changements de longueur extrêmement minimes. Les mesures seront plus précises si l'outil de mesure est plus précis.

Il convient de souligner que lorsque nous représentons des valeurs mesurées, le dernier chiffre a été calculé d'une certaine manière par la personne effectuant la mesure. Par exemple, une personne mesurant la longueur d'un bâton avec une règle remarque qu'il semble être entre 13,2 cm et 13,3 cm, et donc elle doit estimer la valeur du dernier chiffre. La règle des chiffres significatifs stipule que le dernier chiffre inscrit dans une mesure est le premier chiffre avec une certaine incertitude. Commencez par la première valeur mesurée à gauche et comptez le nombre de chiffres jusqu'au dernier chiffre inscrit à droite pour déterminer le nombre de chiffres significatifs dans une valeur. Les chiffres significatifs représentent la précision de l'outil de mesure utilisé pour mesurer une valeur.

Le texte est adapté de <a href="https://openstax.org/books/university-physics-volume-1/pages/1-6-significant-figures">Openstax, University Physics Volume 1, Section: 1.6 Significant Figures. </a>

Règles des chiffres significatifs

Dans toute mesure, la précision de l’outil de mesure est un facteur essentiel. Une règle ordinaire, par exemple, peut mesurer la longueur au plus près ...

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counting significant figures in measurements

Significant figures help students record measurements with the correct level of precision. They show which digits in a number are meaningful and which only help place the decimal point. In science class, this idea matters when writing and comparing measured values.

The rules for significant figures explain how to count these digits in different numbers. Some digits are always counted, while others depend on where they appear in the number. Learning the rules makes it easier to report answers clearly and consistently.

This topic is especially useful in physics and other measurement-based science work. It helps students decide how many digits to keep when writing results from lab work or calculations. That makes numerical answers easier to interpret and compare.

Counting Significant Figures in Measurements

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Significant figures help students record measurements with the correct level of precision. They show which digits in a number are meaningful and which only help place the decimal point. In science class, this idea matters when writing and comparing measured values. The rules for significant figures explain how to count these digits in different numbers. Some digits are always counted, while others depend on where they appear in the number. Learning the rules makes it easier to report answers...

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Learn how to count significant figures in measurements and report scientific values with the right precision for high school science and lab work.

Counting Significant Figures in Measurements | JoVE K12

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Counting Significant Figures in Measurements

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