IGCSE Physics Practical Skills: Key Experiments and Exam Strategies | IGCSE物理实验重点：常见实验与备考策略

📚 IGCSE Physics Practical Skills: Key Experiments and Exam Strategies | IGCSE物理实验重点：常见实验与备考策略

The IGCSE Physics practical exam tests more than your memory of formulas. It checks your ability to measure accurately, control variables, analyse data, and evaluate experimental designs. Understanding the most common experiments and knowing how to approach them will give you a clear advantage.

IGCSE物理实验考试不仅仅考查你对公式的记忆。它检验你准确测量、控制变量、分析数据以及评估实验设计的能力。掌握最常见的实验并知道如何应对它们，会让你在考试中获得明显优势。

---

1. Measuring Length and Time | 测量长度与时间

You must be confident using a ruler, measuring tape, micrometer screw gauge, and stopwatch. For small lengths, use a micrometer or vernier caliper; for large lengths, a tape measure. To measure time for a pendulum, record the time for 20 oscillations and divide by 20 to reduce random error.

你必须熟练使用刻度尺、卷尺、螺旋测微器和秒表。测量小长度时用螺旋测微器或游标卡尺；测量大长度时用卷尺。测量摆的周期时，记录20次全振动的时间再除以20，以减少随机误差。

• Ruler resolution: 1 mm → uncertainty ±0.5 mm

  刻度尺分度值：1 mm → 不确定度 ±0.5 mm

• Stopwatch: human reaction time (~0.2 s) is the main error

  秒表：人的反应时间（约0.2 s）是主要误差来源

• Always measure multiple oscillations to improve precision

  总是测量多个周期以提高精确度

---

2. Measuring Density of Regular and Irregular Objects | 测量规则和不规则物体的密度

Density is defined as mass per unit volume. For a regular solid, measure its dimensions with a ruler and calculate volume. For an irregular object, use a displacement can or measuring cylinder to find the volume of water displaced.

密度的定义是单位体积的质量。对于规则固体，用刻度尺测量尺寸并计算体积。对于不规则物体，用溢水杯或量筒测量排开水的体积。

ρ = m ÷ V

Key steps: record the mass using a balance; record the initial and final water levels; ensure the object sinks completely. Repeat for accuracy and calculate the average density.

关键步骤：用天平记录质量；记录初始和最终水位；确保物体完全浸没。重复测量并计算平均密度。

---

3. Hooke’s Law and Spring Extension | 胡克定律与弹簧伸长

Hang weights on a spring and measure the extension using a ruler positioned behind the spring to avoid parallax error. Plot a graph of force against extension. If the line is straight through the origin, the spring obeys Hooke’s law.

在弹簧下挂砝码，用放在弹簧后面的刻度尺测量伸长量，以避免视差误差。画力-伸长量图像。如果是一条过原点的直线，则弹簧遵循胡克定律。

F = k × x

When the graph becomes curved, the spring has exceeded its elastic limit. Do not completely unload the spring during the experiment if you are still taking readings.

当图像变为曲线时，说明弹簧已超过弹性极限。在读数过程中不要完全卸载弹簧。

---

4. Motion: Measuring Speed and Acceleration | 运动：测量速度与加速度

Use a ticker tape timer or light gates. With a ticker timer, the tape is passed through a vibrating marker that makes dots at fixed time intervals (e.g., 50 dots per second). Measure the distance between dots to find speed.

使用打点计时器或光电门。打点计时器上的振针在纸带上以固定时间间隔（例如每秒50个点）打点。测量点间距可以求出速度。

• Speed = distance between dots ÷ time interval

  速度 = 相邻点距离 ÷ 时间间隔

• Acceleration from a velocity-time graph = gradient

  从速度-时间图像求加速度 = 斜率

For acceleration due to gravity, measure the time for a falling ball between two light gates and use v² = u² + 2as.

测量重力加速度时，让小球通过两个光电门，记录时间，利用 v² = u² + 2as 计算。

---

5. Newton’s Second Law: Force, Mass and Acceleration | 牛顿第二定律：力、质量与加速度

Use a trolley on a friction-compensated runway. Apply a constant force by hanging weights connected to the trolley. Measure acceleration using light gates or ticker timer. Repeat with different masses to investigate the relationship.

在补偿摩擦力的斜面上使用小车。通过悬挂重物向小车施加恒定拉力。用光电门或打点计时器测量加速度。改变质量重复实验，探究关系。

F = m × a

Keep the total mass constant when varying force, and keep force constant when varying mass. This is controlled variable technique.

改变力时保持总质量不变，改变质量时保持力不变。这就是控制变量法。

---

6. Conservation of Momentum in Collisions | 碰撞中的动量守恒

Use two trolleys on a linear air track. Measure their speeds before and after collision using light gates. The principle: total momentum before = total momentum after (when no external force acts).

在水平气垫导轨上使用两辆小车。用光电门测量碰撞前后的速度。原理：无外力作用时，碰撞前总动量等于碰撞后总动量。

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

Ensure the track is level to avoid gravity effects. Take readings quickly after collision, and check whether the collision is elastic or inelastic by comparing kinetic energies.

确保导轨水平以避免重力影响。碰撞后立即读数，并通过比较动能判断碰撞是弹性碰撞还是非弹性碰撞。

---

7. Specific Heat Capacity of a Metal Block | 金属块的比热容

Wrap a metal block (e.g., aluminium) with insulating material. Insert an electric heater into a hole, and a thermometer into another hole. Record the temperature rise over a measured time while supplying a known power.

用绝热材料包裹金属块（如铝块）。在一个孔中插入电加热器，在另一个孔中插入温度计。在已知功率的加热过程中记录温度升高。

E = m × c × ΔT

Energy supplied = power × time. Compare with energy absorbed by the metal to find c. Common errors include heat loss to surroundings and incomplete insulation.

提供的能量 = 功率 × 时间。与金属吸收的能量比较，求出比热容c。常见误差包括向周围散热和隔热不完善。

---

8. Electrical Circuits: Resistance and Ohm’s Law | 电路：电阻与欧姆定律

Set up a circuit with a power supply, resistor, ammeter in series, and voltmeter in parallel to the resistor. Vary the voltage using a variable resistor and record current and voltage readings. Plot current against voltage.

用电源、电阻、串联的电流表和与电阻并联的电压表组成电路。用滑动变阻器改变电压，记录电流和电压读数。画电流-电压图像。

V = I × R

For a metallic resistor at constant temperature, the line is straight through the origin. For a filament lamp, the line curves due to increasing resistance as temperature rises. For a diode, current flows mainly in one direction.

对于温度恒定的金属电阻，图像是过原点的直线。对于小灯泡，图像会弯曲，因为温度升高导致电阻增大。对于二极管，电流主要沿一个方向流动。

---

9. Light: Reflection and Refraction | 光：反射与折射

For reflection, use a plane mirror, ray box, and a protractor to measure the angle of incidence and angle of reflection. They should be equal. For refraction, pass a ray through a transparent block and measure angles in air and in the block.

反射实验使用平面镜、光线盒和量角器测量入射角和反射角。二者应相等。折射实验让光线穿过透明玻璃砖，测量空气中和玻璃中的角度。

n = sin i ÷ sin r

Always mark the ray positions with crosses or dots to improve accuracy. Draw the normal line at 90° to the surface. For total internal reflection, increase the angle of incidence beyond the critical angle.

总是用叉号或点号标记光线位置以提高准确性。法线应与界面成90°。对于全内反射，使入射角大于临界角。

---

10. Waves: Speed, Frequency and Wavelength | 波动：速度、频率与波长

Use a ripple tank with a stroboscope to measure wave frequency and wavelength. Place a barrier to create straight waves. Measure the distance between successive wavefronts to obtain wavelength, and count waves per second for frequency.

使用带有频闪观测器的水波槽测量波频和波长。放置障碍物产生直线波。测量相邻波前之间的距离得到波长，数每秒的波数得到频率。

v = f × λ

For a vibrating string, adjust the frequency until a standing wave forms. The wavelength is twice the distance between adjacent nodes. This experiment helps verify the wave equation.

对于振动弦线，调节频率直到形成驻波。波长等于相邻节点间距离的两倍。该实验有助于验证波速公式。

---

11. Electromagnetic Induction | 电磁感应

Move a magnet into and out of a coil connected to a sensitive ammeter. The deflection indicates the induced current. The direction of deflection reverses when the magnet’s motion or polarity is reversed. Faster motion and stronger magnets produce greater deflection.

将磁铁插入和拔出连接灵敏电流计的线圈。偏转显示感应电流的方向。当磁铁运动方向或磁极反向时，偏转方向也会反向。更快地运动和更强的磁铁会使偏转更大。

Factors that affect the induced EMF: number of turns, magnet speed, magnet strength, and whether the coil has a soft iron core. Use a bar magnet for a clean demonstration of the effect.

影响感应电动势的因素：线圈匝数、磁铁速度、磁铁强度以及线圈中是否插入软铁芯。使用条形磁铁可以清晰地演示这一效应。

---

12. Exam Strategies and Error Analysis | 考场策略与误差分析

During the practical exam, always read instruments to one decimal place beyond their smallest division if possible. Record results in a table with units and headings. Draw graphs with labelled axes, a suitable scale, and a line of best fit.

在实验考试中，尽量将仪器读数读到最小分度后的下一位。在表格中记录结果，包含单位和表头。画图时要有标注清楚的坐标轴、合适的比例尺和最佳拟合线。

• Identify systematic errors: these shift all results equally, e.g., zero error

  识别系统误差：它们使所有结果同向偏移，例如零误差

• Identify random errors: these scatter results, e.g., timing uncertainty

  识别随机误差：它们使结果分散，例如计时不确定度

• Suggest improvements: repeat readings, use finer apparatus, control variables

  提出改进：重复测量、使用更精细的仪器、控制变量

Always include a conclusion that links the plotted graph to the theory. Say whether the data supports the expected straight-line relationship. Mention anomalous results and possible causes.

始终写出将图像与理论联系起来的结论。说明数据是否支持预期的直线关系，并提到异常结果及其可能原因。

Published by TutorHao | Physics Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）