Name: measurement precision and significant figures
Uploaded: 2023-04-30T10:48:20.000Z
Duration: 1 min 44 s
Channel: JoVE

La certeza de la medición depende de dos factores: el número de dígitos de la medición y la precisión del instrumento utilizado.
En una cantidad medida, todos los dígitos, incluido el último dígito incierto, se denominan cifras significativas y se pueden determinar mediante reglas específicas.
Cualquier dígito distinto de cero y todos los ceros cautivos, que se encuentran entre dos dígitos distintos de cero, son significativos. Por ejemplo, 28 tiene dos cifras significativas, mientras que 26,25 tiene cuatro y 208 tiene tres.
Los ceros a la izquierda nunca son significativos, ya que solo ubican el punto decimal. Por ejemplo, 0,00208 tiene tres cifras significativas. Tales cantidades se pueden expresar usando notaciones exponenciales. Por lo tanto, 0,00208 se puede escribir como 2,08 × 10−3.
Los ceros finales solo son significativos en los números con formato decimal: 2200 tiene dos ceros finales y dos cifras significativas, mientras que 2200.0 y 2200.1 tienen 5 cifras significativas.
En el caso de las cantidades sin decimales, el significado de los ceros finales se vuelve ambiguo. Por lo tanto, 2200 se puede escribir como 2,2 × 103 con dos cifras significativas o 2,20 x 103 con tres cifras significativas.

reglas para las cifras significativas

En cualquier medición, la precisión de la herramienta de medición es un factor esencial. Por ejemplo, una regla ordinaria puede medir la longitud hasta el milímetro más cercano; por otro lado, un calibrador puede medir la longitud hasta el centésimo de milímetro más cercano. Como resultado, el calibrador es una herramienta de medición más precisa porque puede medir cambios extremadamente pequeños en la longitud. Las mediciones serán más exactas si la herramienta de medición es más precisa. Se debe enfatizar que cuando representamos valores medidos, la última cifra ha sido calculada de alguna manera por la persona que realiza la medición. Por ejemplo, una persona que mide la longitud de un palo con una regla nota que parece estar entre 13,2 cm y 13,3 cm, por lo que debe estimar el valor de la última cifra. La regla de las cifras significativas establece que la última cifra registrada en una medición es la primera cifra con cierta incertidumbre. Comienza con el primer valor medido a la izquierda y cuenta el número de cifras hasta la última cifra escrita a la derecha para determinar el número de cifras significativas en un valor. Las cifras significativas representan la precisión de la herramienta de medición utilizada para medir un valor. El texto es adoptado 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>

Reglas para las cifras significativas

En cualquier medición, la precisión de la herramienta de medición es un factor esencial. Una regla ordinaria, por ejemplo, puede medir la longitud ...

Education

Educación

JoVE Core

Physics

Física

Unit 1

Unidad 1

Units, Dimensions, and Measurements

Unidades, dimensiones y mediciones

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

Rules for Significant Figures

measurement precision and significant figures

Measurement precision depends on the tool used, and significant figures show that precision. A ruler can measure length to the closest millimeter. A caliper can measure length to the nearest 0.01 mm, so it gives a more precise measurement because it can detect very small changes in length.

When a value is written from a measurement, the last digit is not exact. The person making the measurement must estimate that digit. For example, a stick that seems to fall between 13.2 cm and 13.3 cm must be recorded with a guessed last digit.

The last digit in a measurement is the first digit with some uncertainty. To find the number of significant figures, start with the first measured value on the left and count through the last digit written on the right. Significant figures show how precise the measuring tool was when the value was recorded.

Measurement Precision and Significant Figures

measurement-precision-and-significant-figures

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Measurement precision depends on the tool used, and significant figures show that precision. A ruler can measure length to the closest millimeter. A caliper can measure length to the nearest 0.01 mm, so it gives a more precise measurement because it can detect very small changes in length. When a value is written from a measurement, the last digit is not exact. The person making the measurement must estimate that digit. For example, a stick that seems to fall between 13.2 cm and 13.3 cm must...

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key terms and concepts

Learn how ruler and caliper precision affects measurements and how to count significant figures from the first measured digit to the uncertain last digit.

Measurement Precision and Significant Figures | JoVE K12

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Measurement Precision and Significant Figures

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