Measurement-Physics

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Measurement Noun

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[mezh-er-muhnt]

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Measurement

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The process of comparing an unknown quantity to a known standard in order to quantify an observation.

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Example: This speedometer is an instrument that measures speed, a physical quantity. It shows the measurement with a number and a unit (km/h).

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Uncertainty Noun

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[uhn-sur-tn-tee]

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Uncertainty

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A quantitative indication of the possible error in a measurement, representing the range within which the true value lies.

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Example: This diagram shows how to read a graduated cylinder, where the curved liquid surface (meniscus) means the exact volume must be estimated, introducing measurement uncertainty.

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Precision Noun

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[pri-sizh-uhn]

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Precision

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The degree of exactness of a measurement, which is determined by the instrument and technique used to make it.

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Example: This image uses targets to show that precision in measurement means getting consistent results, like shots clustered together, even if they miss the bullseye.

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Accuracy Noun

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[ak-yuh-ruh-see]

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Accuracy

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A description of how closely the results of a measurement agree with the accepted or 'real' value.

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Example: Accuracy describes how close a measurement is to the true value. The dots on the target show that being accurate means hitting near the bullseye.

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Significant Figures Noun

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[sig-nif-i-kuhnt fig-yerz]

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Significant Figures

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The digits in a measured value that carry meaning contributing to its precision, including all certain digits plus one estimated digit.

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Example: This diagram breaks down a number to show different types of digits (leading, non-zero, trailing), which helps determine which ones are significant in a measurement.

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Two-point calibration Noun

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[too-point kal-i-brey-shuhn]

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Two-point calibration

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A method for checking an instrument's accuracy by verifying its readings at zero and at a known standard value.

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Example: A thermometer is calibrated by checking its readings at two known fixed points: the freezing point (ice, 0°C) and boiling point (boiling water, 100°C).

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Parallax Noun

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[par-uh-laks]

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Parallax

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The apparent shift in an object's position when viewed from different angles, which can cause errors in measurement.

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Example: As the Earth orbits the Sun, a nearby star appears to shift its position against the background of distant stars. This apparent shift is called parallax.

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Radiocarbon Dating Noun

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[rey-dee-oh-kahr-buhn dey-ting]

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Radiocarbon Dating

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A technique used to determine the age of organic materials by measuring the decay of the carbon-14 isotope.

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Example: This graph shows how a radioactive substance decays over time. After one half-life, 50% remains; after two, 25% remains, a predictable rate.

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Atomic Clock Noun

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[uh-tom-ik klok]

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Atomic Clock

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An extremely precise timekeeping device that uses the resonant frequency of atoms as its standard for measurement.

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Example: This diagram shows a Cesium-133 atom. Atomic clocks work by measuring the consistent, natural vibration of the atom's outer electron to keep extremely accurate time.

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Micrometer Noun

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[mahy-krom-i-ter]

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Micrometer

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A precision instrument used for making very small and exact measurements of distance, thickness, or diameter.

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Example: This diagram shows the main parts of a micrometer, a tool used to make very precise measurements of small objects in physics and engineering.