📚 Calibration | 校准
Calibration is the process of comparing a measuring instrument's reading with a known standard or reference value. In A-Level physics, calibration is essential for ensuring that measurements are trustworthy and that experimental results can be compared with theoretical predictions.
校准是将测量仪器的读数与已知标准或参考值进行比较的过程。在 A-Level 物理中,校准对于确保测量可靠、使实验结果能够与理论预测相比较至关重要。
1. What is Calibration? | 什么是校准?
Calibration involves adjusting or checking an instrument against a standard. For example, a thermometer may be calibrated using the freezing and boiling points of water, which are fixed reference temperatures. The reading of the instrument is then adjusted so that it agrees with the known values.
校准涉及根据标准来调整或检查仪器。例如,可使用水的凝固点和沸点这些固定的参考温度来校准温度计,然后调整仪器的读数,使其与已知值一致。
A calibrated instrument produces readings that are directly traceable to a recognised standard, such as those maintained by national laboratories. This traceability is fundamental in all quantitative science.
经过校准的仪器产生的读数可直接溯源到公认的标准,例如由国家实验室维护的标准。这种可追溯性是一切定量科学的基础。
In practice, calibration often results in a correction that must be added to or subtracted from the raw reading. Alternatively, a calibration curve can be plotted to show the relationship between the instrument's output and the true value.
在实践中,校准通常会得到一个必须从原始读数中加上或减去的修正量。或者,可以绘制校准曲线,以显示仪器输出与真实值之间的关系。
2. Why is Calibration Important? | 为什么校准重要?
Calibration is important because all instruments are subject to manufacturing tolerances, drift over time, and environmental influences. Without calibration, measurements may be consistently wrong, leading to incorrect conclusions in experiments.
校准很重要,因为所有仪器都会受到制造公差、时间漂移和环境因素的影响。如果没有校准,测量可能会持续出错,导致实验得出错误结论。
For example, a voltmeter that reads 1.5 V when the true value is 1.45 V will give systematically high readings. This error will affect every voltage measurement in an experiment, potentially invalidating results.
例如,一个电压表在真实值为 1.45 V 时读数为 1.5 V,那么它的读数会系统性地偏高。这种误差会影响实验中的每次电压测量,可能使结果失效。
Calibration also allows different instruments to be compared. If two thermometers are calibrated against the same standard, their readings can be considered equivalent within the stated uncertainty.
校准还允许对不同仪器进行比较。如果两支温度计针对同一标准进行校准,那么在规定的不确定度范围内,它们的读数可被视为等效。
3. Accuracy, Precision and Calibration | 准确度、精密度与校准
Accuracy describes how close a measured value is to the true value. Precision describes how close repeated measurements are to each other. An instrument can be precise but inaccurate if it has a systematic error; calibration corrects such errors and improves accuracy.
准确度描述测量值接近真实值的程度。精密度描述重复测量值彼此接近的程度。如果仪器存在系统误差,则可能精密度高但准确度低;校准可纠正这类误差并提高准确度。
- Accuracy | 准确度:nearness to the true value | 与真实值的接近程度。
- Precision | 精密度:repeatability of readings | 读数的可重复性。
- Calibration | 校准:reduces systematic error, improving accuracy | 减少系统误差,提高准确度。
Even after calibration, random errors remain. These are caused by unpredictable fluctuations and can be reduced by taking multiple readings and averaging, but not wholly eliminated by calibration.
即使校准后,随机误差仍然存在。这些误差由不可预测的波动引起,可通过多次读数并取平均值来减少,但不能完全靠校准消除。
4. Systematic Errors and Zero Errors | 系统误差与零误差
A systematic error affects all measurements in the same direction by a similar amount. One common type is a zero error, where the instrument does not read zero when it should. For example, a balance may show 0.05 g when empty, and a micrometer may read 0.01 mm with closed jaws.
系统误差以相同方向、相似大小影响所有测量。常见的一种是零误差,即仪器在应该读数为零时不为零。例如,天平空载时可能显示 0.05 g,千分尺在闭合时可能读数为 0.01 mm。
Zero errors are corrected by subtracting the zero reading from all subsequent readings, or by physically adjusting the instrument. Other systematic errors include thermal expansion, electrical resistance in leads, and parallax when reading a scale.
零误差的修正方法是从所有后续读数中减去零读数,或对仪器进行物理调整。其他系统误差包括热膨胀、导线中的电阻以及读取刻度时的视差。
Calibration can identify the magnitude of a systematic error at each point on the scale. A calibration curve then provides the correction needed at any intermediate reading.
校准可以确定标尺上每个点的系统误差大小。校准曲线随后为任何中间读数提供所需的修正。
5. Calibration Curves | 校准曲线
A calibration curve is a graph showing the relationship between the measured reading from an instrument and the known true value. The vertical axis often represents the true value, while the horizontal axis represents the instrument's raw reading. Alternatively, the correction can be plotted against the reading.
校准曲线是显示仪器测量读数与已知真实值之间关系的曲线图。纵轴通常表示真实值,横轴表示仪器的原始读数。或者,可以将修正量相对于读数作图。
For an ideal instrument, the calibration curve is a straight line through the origin with a gradient of 1. Real instruments deviate from this; the curve may have an intercept or a different gradient, or it may be curved.
对于理想仪器,校准曲线是穿过原点的直线,梯度为 1。实际仪器会偏离这一理想情况;曲线可能有截距或不同的梯度,或可能是弯曲的。
Once a calibration curve is drawn, it can be used to convert any future raw reading into a corrected value. This is especially useful when the response of the instrument is not linear.
一旦绘制了校准曲线,就可以将其用于将任何未来的原始读数转换为修正值。这在仪器响应非线性时尤其有用。
6. How to Construct a Calibration Curve | 如何绘制校准曲线
To construct a calibration curve, you need a set of known reference values and the corresponding instrument readings. The reference values are provided by standards, such as calibrated weights, standard resistors, or fixed-point temperature cells.
要绘制校准曲线,需要一组已知参考值和对应的仪器读数。参考值由标准提供,例如校准砝码、标准电阻或固定点温度单元。
For example, in an experiment to calibrate a spring balance, known masses are hung from the spring, and the extension is measured. The true force is calculated as F = mg, where g = 9.81 m s-2.
例如,在标定弹簧测力计的实验中,将已知质量的砝码挂在弹簧上,并测量伸长量。真实力用 F = mg 计算,其中 g = 9.81 m s-2。
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Accuracy | 准确度:nearness to the true value | 与真实值的接近程度。
Precision | 精密度:repeatability of readings | 读数的可重复性。
Calibration | 校准:reduces systematic error, improving accuracy | 减少系统误差,提高准确度。
📚 Calibration | 校准
Calibration is the process of comparing a measuring instrument's reading with a known standard or reference value. In A-Level physics, calibration is essential for ensuring that measurements are trustworthy and that experimental results can be compared with theoretical predictions.
校准是将测量仪器的读数与已知标准或参考值进行比较的过程。在 A-Level 物理中,校准对于确保测量可靠、使实验结果能够与理论预测相比较至关重要。
1. What is Calibration? | 什么是校准?
Calibration involves adjusting or checking an instrument against a standard. For example, a thermometer may be calibrated using the freezing and boiling points of water, which are fixed reference temperatures. The reading of the instrument is then adjusted so that it agrees with the known values.
校准涉及根据标准来调整或检查仪器。例如,可使用水的凝固点和沸点这些固定的参考温度来校准温度计,然后调整仪器的读数,使其与已知值一致。
A calibrated instrument produces readings that are directly traceable to a recognised standard, such as those maintained by national laboratories. This traceability is fundamental in all quantitative science.
经过校准的仪器产生的读数可直接溯源到公认的标准,例如由国家实验室维护的标准。这种可追溯性是一切定量科学的基础。
In practice, calibration often results in a correction that must be added to or subtracted from the raw reading. Alternatively, a calibration curve can be plotted to show the relationship between the instrument's output and the true value.
在实践中,校准通常会得到一个必须从原始读数中加上或减去的修正量。或者,可以绘制校准曲线,以显示仪器输出与真实值之间的关系。
2. Why is Calibration Important? | 为什么校准重要?
Calibration is important because all instruments are subject to manufacturing tolerances, drift over time, and environmental influences. Without calibration, measurements may be consistently wrong, leading to incorrect conclusions in experiments.
校准很重要,因为所有仪器都会受到制造公差、时间漂移和环境因素的影响。如果没有校准,测量可能会持续出错,导致实验得出错误结论。
For example, a voltmeter that reads 1.5 V when the true value is 1.45 V will give systematically high readings. This error will affect every voltage measurement in an experiment, potentially invalidating results.
例如,一个电压表在真实值为 1.45 V 时读数为 1.5 V,那么它的读数会系统性地偏高。这种误差会影响实验中的每次电压测量,可能使结果失效。
Calibration also allows different instruments to be compared. If two thermometers are calibrated against the same standard, their readings can be considered equivalent within the stated uncertainty.
校准还允许对不同仪器进行比较。如果两支温度计针对同一标准进行校准,那么在规定的不确定度范围内,它们的读数可被视为等效。
3. Accuracy, Precision and Calibration | 准确度、精密度与校准
Accuracy describes how close a measured value is to the true value. Precision describes how close repeated measurements are to each other. An instrument can be precise but inaccurate if it has a systematic error; calibration corrects such errors and improves accuracy.
准确度描述测量值接近真实值的程度。精密度描述重复测量值彼此接近的程度。如果仪器存在系统误差,则可能精密度高但准确度低;校准可纠正这类误差并提高准确度。
Even after calibration, random errors remain. These are caused by unpredictable fluctuations and can be reduced by taking multiple readings and averaging, but not wholly eliminated by calibration.
即使校准后,随机误差仍然存在。这些误差由不可预测的波动引起,可通过多次读数并取平均值来减少,但不能完全靠校准消除。
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A systematic error affects all measurements in the same direction by a similar amount. One common type is a zero error, where the instrument does not read zero when it should. For example, a balance may show 0.05 g when empty, and a micrometer may read 0.01 mm with closed jaws.
系统误差以相同方向、相似大小影响所有测量。常见的一种是零误差,即仪器在应该读数为零时不为零。例如,天平空载时可能显示 0.05 g,千分尺在闭合时可能读数为 0.01 mm。
Zero errors are corrected by subtracting the zero reading from all subsequent readings, or by physically adjusting the instrument. Other systematic errors include thermal expansion, electrical resistance in leads, and parallax when reading a scale.
零误差的修正方法是从所有后续读数中减去零读数,或对仪器进行物理调整。其他系统误差包括热膨胀、导线中的电阻以及读取刻度时的视差。
Calibration can identify the magnitude of a systematic error at each point on the scale. A calibration curve then provides the correction needed at any intermediate reading.
校准可以确定标尺上每个点的系统误差大小。校准曲线随后为任何中间读数提供所需的修正。
5. Calibration Curves | 校准曲线
A calibration curve is a graph showing the relationship between the measured reading from an instrument and the known true value. The vertical axis often represents the true value, while the horizontal axis represents the instrument's raw reading. Alternatively, the correction can be plotted against the reading.
校准曲线是显示仪器测量读数与已知真实值之间关系的曲线图。纵轴通常表示真实值,横轴表示仪器的原始读数。或者,可以将修正量相对于读数作图。
For an ideal instrument, the calibration curve is a straight line through the origin with a gradient of 1. Real instruments deviate from this; the curve may have an intercept or a different gradient, or it may be curved.
对于理想仪器,校准曲线是穿过原点的直线,梯度为 1。实际仪器会偏离这一理想情况;曲线可能有截距或不同的梯度,或可能是弯曲的。
Once a calibration curve is drawn, it can be used to convert any future raw reading into a corrected value. This is especially useful when the response of the instrument is not linear.
一旦绘制了校准曲线,就可以将其用于将任何未来的原始读数转换为修正值。这在仪器响应非线性时尤其有用。
6. How to Construct a Calibration Curve | 如何绘制校准曲线
To construct a calibration curve, you need a set of known reference values and the corresponding instrument readings. The reference values are provided by standards, such as calibrated weights, standard resistors, or fixed-point temperature cells.
要绘制校准曲线,需要一组已知参考值和对应的仪器读数。参考值由标准提供,例如校准砝码、标准电阻或固定点温度单元。
For example, in an experiment to calibrate a spring balance, known masses are hung from the spring, and the extension is measured. The true force is calculated using the equation:
例如,在标定弹簧测力计的实验中,将已知质量的砝码挂在弹簧上,并测量伸长量。真实力用以下公式计算:
F = m g
where F is the force in newtons, m is the mass in kilograms, and g is the gravitational field strength (9.81 N kg⁻¹ on Earth).
其中 F 为力(单位牛顿),m 为质量(单位千克),g 为重力场强度(地球上取 9.81 N kg⁻¹)。
For a thermocouple, the known reference values may be the temperatures of melting ice, boiling water, and other fixed points. The emf produced at each temperature is measured, and a graph of emf against temperature is plotted.
对于热电偶,已知参考值可以是冰点、沸水及其他固定点的温度。测量每个温度下产生的电动势,并绘制电动势随温度变化的曲线。
7. Linear Calibration and Best-Fit Lines | 线性校准与最佳拟合线
Many instruments have a linear response: the reading is directly proportional to the true value over a certain range. In this case, the calibration curve is a straight line, and the relationship can be written as:
许多仪器具有线性响应:在一定范围内,读数与真实值成正比。在这种情况下,校准曲线是一条直线,其关系可写为:
R = k T + c
where R is the raw reading, T is the true value, k is the sensitivity constant, and c is the zero offset.
其中 R 是原始读数,T 是真实值,k 是灵敏度常数,c 是零位偏移。
The best-fit line through the data points is drawn using graph plotting techniques. The gradient and intercept provide the calibration equation, allowing corrections to be applied algebraically without reading the graph each time.
用绘图技术绘制穿过数据点的最佳拟合线。梯度和截距提供校准方程,从而无需每次读图即可通过代数方式应用修正。
When drawing a best-fit line, data points should be spread across the full measurement range. Outliers should be investigated rather than automatically ignored.
绘制最佳拟合线时,数据点应分布在完整测量范围内。应调查异常值,而不是自动忽略。
8. Nonlinear Calibration | 非线性校准
Some instruments, such as certain thermistors and strain gauges, have a nonlinear response. Their resistance or output changes by different amounts for each unit of the measured quantity. A linear line cannot adequately represent such data.
某些仪器(如某些热敏电阻和应变片)具有非线性响应。其电阻或输出对每个单位的被测物理量的变化量并不相同。直线无法充分表示此类数据。
For nonlinear calibration, the calibration curve is a smooth curve passing through the plotted points. Interpolation is then used to estimate the true value corresponding to any raw reading between two known points.
对于非线性校准,校准曲线是通过所绘各点的平滑曲线。然后使用插值法来估计与两个已知点之间任意原始读数对应的真实值。
Care must be taken not to extrapolate beyond the range of the calibration data, as the instrument's behaviour may change outside the measured range.
必须注意不要外推到校准数据范围之外,因为仪器在测量范围之外的行为可能发生变化。
9. Calibration of Measuring Instruments | 测量仪器的校准
Different instruments require different calibration techniques. For example, a micrometer screw gauge is checked against slip gauges of known thickness; a voltmeter is compared with a standard cell; a stopwatch is compared with a precision time base.
不同的仪器需要不同的校准技术。例如,千分尺用已知厚度的量块进行校验;电压表与标准电池比较;秒表与精密时基比较。
Instrument Standard / Method Typical Error Thermometer Freezing / boiling points of water ±0.1 °C Voltmeter Standard reference cell ±0.01 V Top-pan balance Standard masses ±0.001 g In school laboratories, calibration is often done using simple known quantities. For instance, a spring can be calibrated using standard masses and the equation F = m g. A light gate can be calibrated using a known frequency signal or a rotating disc with slots.
在学校实验室中,通常使用简单的已知量进行校准。例如,弹簧可以用标准砝码和公式 F = m g 来标定。光门可以用已知频率信号或带槽的旋转圆盘来标定。
10. Calibration in Practical Work | 实验中的校准
In A-Level practical assessments, you are expected to calibrate instruments correctly and record calibration data. This may involve creating a table of raw readings and known true values, plotting a calibration curve, and using it to correct subsequent measurements.
在 A-Level 实验评估中,你应正确校准仪器并记录校准数据。这可能涉及制作原始读数和已知真实值的表格、绘制校准曲线,并用它来修正后续测量。
For example, when measuring the specific heat capacity of a metal, a thermometer should be calibrated against a standard thermometer. Any offset is then applied to all temperature readings before calculating the heat capacity.
例如,在测量金属的比热容时,应将温度计与标准温度计进行校准。然后在计算热容之前,将所有温度读数应用该偏移量。
Always record the uncertainty in calibration. If the standard itself has an uncertainty, this must be propagated into the final measurement uncertainty.
始终记录校准中的不确定度。如果标准本身具有不确定度,则必须将其传递到最终的测量不确定度中。
11. Sources of Uncertainty in Calibration | 校准中的不确定度来源
Calibration does not eliminate uncertainty; it quantifies and reduces it. Sources of uncertainty include the accuracy of the standard, the resolution of the instrument, environmental variations, and human reading errors.
校准并不能消除不确定度;它量化并减少了不确定度。不确定度来源包括标准的准确度、仪器的分辨率、环境变化和人工读数误差。
This contributes directly to the uncertainty of any measurement made using that standard.
标准本身并非完美。例如,一个标准砝码可能经校准后不确定度为 ±0.01 mg。这直接贡献于使用该标准进行的任何测量的不确定度。
When creating a calibration curve, the uncertainties in both the true value and the raw reading should be shown as error bars. The line or curve should fit within these error bars wherever possible.
绘制校准曲线时,真实值和原始读数的不确定度都应显示为误差棒。曲线或直线应尽可能在这些误差棒内拟合。
12. Summary | 总结
Calibration is a fundamental procedure in experimental physics. It ensures that measurements are accurate by comparing instrument readings with known standards. Calibration curves allow systematic errors to be corrected, especially when the instrument response is nonlinear.
校准是实验物理中的基本程序。它通过将仪器读数与已知标准进行比较,确保测量准确。校准曲线允许修正系统误差,特别是在仪器响应非线性时。
Understanding the distinction between accuracy and precision, recognising zero errors, constructing calibration curves, and propagating calibration uncertainties are essential skills for A-Level physics examinations and scientific work.
理解准确度与精密度之间的区别、识别零误差、绘制校准曲线以及传递校准不确定度,是 A-Level 物理考试和科学工作中必不可少的技能。
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或截图后用「扫一扫 → 相册」选择本图公众号:tutorhao - having English text, then a line break, then Chinese text. This is not two
- containing both English and Chinese separated by
,紧跟写中文
配对" — this suggests within a section, each point has an English paragraph followed by Chinese paragraph. For lists, we can use
,紧跟写中文
" strictly means paragraphs. To be safe, we can avoid lists for paired content and use paragraphs. But we can still use lists for simple juxtaposition. However the spec explicitly says lists use