📚 Experimental Tools for Physics | 物理实验工具
In experimental physics, the quality of data depends heavily on the correct selection and use of measurement instruments. From mechanical tools like vernier calipers to digital sensors and data-logging software, each device has a specific precision, potential sources of uncertainty, and best practices that an IB student must master. This article provides a comprehensive overview of the key experimental tools used in IB Physics, covering their principles, reading techniques, uncertainty considerations, and their role in producing reliable scientific results.
在实验物理中，数据的质量在很大程度上取决于测量仪器的正确选择与使用。从游标卡尺这样的机械工具到数字传感器和数据记录软件，每种设备都有特定的精度、潜在的不确定度来源和最佳操作规范，这些都是IB学生必须掌握的。本文全面概述了IB物理中使用的关键实验工具，涵盖其原理、读数方法、不确定度考量及其在获得可靠科学结果中的作用。
1. Vernier Calipers | 游标卡尺
A vernier caliper is designed to measure internal and external dimensions as well as depths, typically with a precision of 0.1 mm or 0.05 mm. The main scale is graduated in millimetres, while the sliding vernier scale provides a fraction of the smallest main-scale division.
游标卡尺用于测量内外径及深度，典型精度为0.1毫米或0.05毫米。主尺以毫米为单位，而滑动的游标尺能提供比主尺最小刻度更精细的读数。
The least count (resolution) is found by dividing the smallest main-scale division by the number of divisions on the vernier scale. For example, a caliper with 20 vernier divisions covering 19 mm has a least count of 0.05 mm.
分度值（分辨率）由主尺最小刻度除以游标尺上的分度数得出。例如，20个游标分度对应主尺19毫米的卡尺，其分度值为0.05毫米。
To take a reading, note the main-scale graduation just before the vernier zero mark, then identify the vernier division that aligns perfectly with any main-scale division. Before use, close the jaws completely and check for zero error; if the vernier zero does not coincide with the main-scale zero, the reading must be corrected.
读数时，先读取游标零线之前的主尺刻度，然后找到与主尺某刻度线完全对齐的游标刻度线，此即小数部分。使用前需完全闭合卡爪检查零误差；若游标零线与主尺零线不重合，则必须修正读数。
2. Micrometer Screw Gauge | 螺旋测微器（千分尺）
A micrometer screw gauge measures small lengths, thicknesses, or wire diameters with a typical precision of 0.01 mm. Its spindle has a pitch of 0.5 mm, and the circular thimble is divided into 50 equal parts, meaning each division corresponds to an axial movement of 0.01 mm.
螺旋测微器用于测量微小长度、厚度或线径，典型精度为0.01毫米。其螺杆螺距为0.5毫米，微分筒圆周分为50个等分，因此每一格代表螺杆轴向移动0.01毫米。
The object is gently clamped between the anvil and the spindle by turning the ratchet until it slips. This ensures a consistent measuring pressure. The reading is the sum of the main scale (barrel) reading and the thimble reading, where the datum line on the barrel is the reference.
通过旋转棘轮使测砧与测微螺杆轻轻夹住物体，直到棘轮打滑，以保持一致的测量压力。读数为套筒主尺读数与微分筒读数之和，以套筒上的水平基准线为参考。
s positive; if above, it is negative. The corrected reading = measured value − zero error.
务必记录零误差：当测砧与螺杆完全闭合时，若微分筒零线位于套筒基准线以下，为正零误差；反之则为负零误差。修正后的读数 = 测量值 − 零误差。
3. Metre Rule and Measuring Tape | 米尺和卷尺
observer must view the scale perpendicularly, and sometimes a set square is used to align the object's end with the graduation.
米尺用于测量长达1米的长度，典型精度为±0.5毫米。为避免视差，观察者必须垂直注视着刻度，有时还可借助三角尺使物体边缘与刻度线对齐。
Measuring tapes are suitable for longer distances, but they can stretch, sag, or suffer from a worn zero point, introducing systematic errors. The end correction should be applied by measuring from a non-zero mark.
卷尺适用于更长的距离，但可能拉伸、下垂或零刻度磨损，引入系统误差。可通过从非零刻度开始测量并施加端点修正来减小这种误差。
sure this length as accurately as possible, and the uncertainty is often taken as ±0.1 cm.
在单摆实验中，摆长是指悬挂点到摆球质心的距离。使用米尺和三角尺有助于尽可能精确地测量此长度，其不确定度通常取±0.1厘米。
4. Electronic Balance | 电子天平
An electronic balance measures mass with a readability of 0.01 g or 0.001 g (milligram balance). The instrument must be placed on a stable, level surface and zeroed (tared) before placing the object on the pan.
电子天平可测量质量，读数能力为0.01克或0.001克（毫克级天平）。仪器必须放在稳固、水平的台面上，在放置物体前需调零（去皮）。
Air currents and mechanical vibrations can affect the reading, so a draft shield is often used for high-resolution balances. Calibration should be checked periodically with reference masses of known value.
气流和机械振动会影响读数，因此高分辨率天平常配防风罩。应定期用已知值的标准砝码检查天平校准状态。
The uncertainty in mass is not merely the display resolution; it is determined by the repeatability of readings when the same mass is measured multiple times. For IB experiments, students should record the resolution and, if possible, the standard deviation from repeated trials.
质量的不确定度并不仅仅是显示分辨率；它由同一质量被多次测量时的重复性决定。在IB实验中，学生应记录分辨率，并尽可能记录重复试验的标准偏差。
5. Stopwatch and Timer | 秒表和计时器
A digital stopwatch typically displays time to 0.01 s, but the dominant source of uncertainty is human reaction time, usually about 0.1–0.2 s. Therefore, the absolute uncertainty for a manually started and stopped interval is taken as 0.2 s (or the measured reaction time).
数字秒表通常显示至0.01秒，但主要的不确定度来源是人的反应时间，通常约为0.1–0.2秒。因此，手动启停所测时间间隔的绝对不确定度取0.2秒（或实际测得的反应时间）。
To reduce the relative uncertainty, one should measure the time for several periods (e.g., 20 oscillations of a pendulum) and then divide by the number of periods. Using a fiducial mark, such as the centre of the swing, helps to synchronise the start and stop actions.
为减小相对不确定度，应测量多个周期（例如单摆摆动20次）的时间，再除以周期数。使用参考标记，如摆动的中心位置，有助于同步开始和停止的时间点。
Photogate timers and motion sensors can eliminate reaction-time errors entirely, providing timing precision of microseconds to milliseconds. They are linked to data-logging interfaces, which are covered later.
光电门计时器和运动传感器能完全消除反应时间误差，提供微秒至毫秒级的时间精度。它们与数据记录接口连接，将在后文讨论。
6. Ammeter and Voltmeter | 电流表和电压表
An ammeter measures electric current and is connected in series; it must have a very low internal resistance so that it does not significantly alter the current. A voltmeter measures potential difference and is placed in parallel; it requires a very high internal resistance to minimise the current drawn from the circuit.
电流表用于测量电流，必须串联在电路中；它的内阻必须非常低，以免显著改变电路中的电流。电压表用于测量电位差，应并联在待测元件两端；它需要非常高的内阻，以尽量减小从电路中吸取的电流。
ng uncertainty is usually taken as half the smallest scale division, e.g., ±0.5 mA for a 0–1 mA meter with 100 divisions.
指针式仪表通常在刻度盘后面装有镜子以避免视差：当指针与其镜像重合时，说明视线正对刻度。此类仪表读数的不确定度通常取最小刻度的一半，例如量程0–1 mA、分为100格的电流表，不确定度取±0.5 mA。
input impedance is finite. The uncertainty for a digital instrument is often specified as '±(x% of reading + y digits)'. Always consult the manufacturer' t, and check if the internal resistance of the meter influences the circuit significantly.
数字式仪表直接显示读数，但其输入阻抗有限。数字仪表的准确度通常表示为"±(读数的x% + y个字)"。务必查阅厂商数据手册，并检查仪表内阻是否对被测电路有明显影响。
7. Multimeter | 万用表
A digital multimeter (DMM) integrates the functions of an ammeter, voltmeter, and ohmmeter, and often includes continuity, capacitance, and frequency measurements. Selecting the correct range is essential to obtain a reading with the maximum number of significant figures without overloading the meter.
数字万用表集电流表、电压表和欧姆表于一体，通常还包含通断测试、电容和频率测量功能。选择正确的量程至关重要，这样才能在不导致过载的情况下获得最多有效数字的读数。
When measuring resistance, the component must be disconnected from any power source. The meter passes a small known current through the resistor and measures the resulting voltage drop. The test leads may contribute a fraction of an ohm, so zeroing the lead resistance (relative mode) is advisable for low-value resistors.
测量电阻时，必须将待测元件与所有电源断开。万用表施加一个已知的小电流流经电阻，并测量其两端压降。表笔引线自身可能包含零点几欧姆的电阻，因此测量低值电阻时，建议先归零引线电阻（相对模式）。
Uncertainty in resistance mode is typically a percentage of reading plus a number of least-significant digits. For highly precise work, a four-wire (Kelvin) connection eliminates lead resistance errors. Regularly test the multimeter against known standards to maintain confidence in measurements.
电阻测量模式下的不确定度通常是读数的百分比加上末位数字的变化。对于高精度工作，四线（开尔文）接法能消除引线电阻误差。定期用已知标准核验万用表，以保持对测量结果的信心。
8. Cathode-Ray Oscilloscope (CRO) | 阴极射线示波器
An oscilloscope displays voltage as a function of time on a fluorescent screen, enabling the measurement of amplitude, period, frequency, and phase relationships of alternating signals. The vertical attenuator sets the voltage per division (V/div), and the timebase controls the sweep speed (s/div, ms/div, or μs/div).
示波器在荧光屏上显示电压随时间的变化，能测量交流信号的幅度、周期、频率以及相位关系。垂直衰减器设定每格代表的电压值（伏/格），时基控制扫描速度（秒/格、毫秒/格或微秒/格）。
ts on successive cycles and multiplying by the time/div setting. The frequency is f = 1/T.
要确定峰峰值电压，可计算波形最高点与最低点之间的垂直格数，并乘以伏/格设定值。周期T通过计算相邻波形相同点之间的水平格数并乘以时基设定值得到。频率 f = 1/T。
Modern digital storage oscilloscopes (DSOs) can capture single-shot events and perform Fast Fourier Transforms (FFT) to display frequency spectra. In IB Physics labs, CROs are commonly used to study waveforms from signal generators, measure the speed of sound via a microphone, and observe charging/discharging curves in RC circuits.
现代数字存储示波器能捕捉单次瞬态事件，并进行快速傅里叶变换（FFT）显示频谱。在IB物理实验室中，示波器常用于研究信号发生器的波形、通过麦克风测量声速，以及观察RC电路的充放电曲线。
9. Temperature Measurement: Thermometers and Thermocouples | 温度测量：温度计和热电偶
Liquid-in-glass thermometers (alcohol or mercury) provide a simple, inexpensive way to measure temperature. Typical graduations are 0.5 °C or 1 °C. To avoid parallax, read at eye level, and ensure the thermometer is immersed to the depth appropriate for full thermal contact.
液体玻璃温度计（酒精或水银）提供了一种简单、廉价的测温方法。典型刻度为0.5°C或1°C。为避免视差，需平视读数，并确保温度计浸入足够的
Published by TutorHao | IB Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图