📚 Energy Resources and Energy Transfers | 能量资源与能量转移
Energy is the ability to do work, and it comes in many forms that can be transferred, stored or converted from one type to another. Understanding energy resources and how energy transfers occur is a fundamental part of IGCSE Edexcel Science, because it explains how we power our modern world and the impact our choices have on the environment. This article covers everything from the basic forms of energy to Sankey diagrams and efficiency calculations, helping you master the topic for your exams.
能量是做功的能力，它有许多不同的形式，可以被转移、储存或从一种形式转换为另一种形式。理解能源资源以及能量如何转移是IGCSE Edexcel科学的基础部分，因为它解释了我们如何为现代世界提供动力，以及我们的选择对环境有何影响。本文涵盖从能量基本形式到桑基图和效率计算的全部内容，帮助你掌握这一考试主题。
1. Forms of Energy | 能量的形式
Energy can exist in several forms, and in IGCSE Science you need to be able to identify them in different situations. The main forms include kinetic energy (the energy of a moving object), gravitational potential energy (energy stored because of an object’s position in a gravitational field), chemical energy (stored in fuels, food and batteries), elastic potential energy (stored in stretched or compressed objects), thermal energy (heat), electrical energy (carried by moving charges), nuclear energy (stored in atomic nuclei) and light energy (carried by light waves). Sound energy is another form carried by vibrations.
能量可以以多种形式存在，在IGCSE科学中你需要能在不同情境下识别它们。主要形式包括动能（运动物体的能量）、重力势能（因物体在引力场中的位置而储存的能量）、化学能（储存在燃料、食物和电池中）、弹性势能（储存在拉伸或压缩的物体中）、热能（热量）、电能（由移动电荷携带）、核能（储存在原子核中）和光能（由光波携带）。声能是由振动携带的另一种形式。
An example: a ball held above the ground has gravitational potential energy. When it falls, this energy is transferred to kinetic energy. If it hits the ground and deforms, some energy is also stored as elastic potential energy, and eventually most of it spreads out as thermal energy in the surroundings.
例如：一个被举离地面的球具有重力势能。当它下落时，这种能量转移为动能。如果它撞击地面并变形，部分能量也会储存为弹性势能，最终大部分能量会以热能的形式散失到周围环境中。
2. Energy Transfers | 能量转移
Energy can be transferred from one store to another by four main pathways: by heating, by mechanical work (force moving something), by electrical work (charges moving through a circuit) and by radiation (light or sound waves travelling away from a source). In any energy transfer, the total amount of energy is conserved, but it often ends up in less useful stores, such as thermal energy spread into the surroundings.
能量可以通过四种主要途径从一个储存库转移到另一个储存库：加热、机械做功（力使物体移动）、电做功（电荷在电路中移动）和辐射（光或声波从源向外传播）。在任何能量转移中，总能量是守恒的，但它往往会变成不太有用的储存形式，例如扩散到环境中的热能。
For instance, when you use an electric kettle, electrical energy is transferred by electrical work to the heating element, where it increases the thermal store of the water. Some energy is always transferred to the thermal store of the surrounding air – this is dissipated energy and cannot easily be used again.
例如，当你使用电水壶时，电能通过电做功转移到加热元件，使水的热能储存增加。部分能量总会转移到周围空气的热能储存中——这就是耗散的能量，且不易再次利用。
3. Conservation of Energy | 能量守恒
The principle of conservation of energy states that energy cannot be created or destroyed, only transferred from one store to another. This fundamental law means that in any closed system the total energy at the start equals the total energy at the end, even if some of it becomes less useful, such as thermal energy dissipated into the environment.
能量守恒原理表明，能量既不会凭空产生也不会凭空消失，只会从一个储存库转移到另一个储存库。这条基本定律意味着，在任何封闭系统中，初始总能量等于最终总能量，即使部分能量变得不那么有用，例如耗散为环境中的热能。
In an IGCSE exam, you might be asked to explain energy changes in a simple pendulum. At the highest point, the pendulum bob has maximum gravitational potential energy and zero kinetic energy. As it swings down, gravitational potential energy is transferred to kinetic energy, reaching maximum speed at the lowest point. As it rises again, kinetic energy is transferred back to gravitational potential energy. In reality, a little energy is always transferred to thermal stores due to air resistance and friction at the pivot, so the pendulum gradually loses height.
在IGCSE考试中，你可能会被要求解释单摆的能量变化。在最高点，摆锤具有最大的重力势能和零动能。当它向下摆动时，重力势能转移为动能，在最低点达到最大速度。当它再次升高时，动能又转移回重力势能。现实中，由于空气阻力和支点处的摩擦，总会有少量能量转移到热能储存中，因此摆锤的高度逐渐减小。
4. Efficiency | 效率
Efficiency measures how much of the total energy input is transferred into useful energy output. It can be calculated either using energy or power values, and is often expressed as a percentage. The useful energy output is always less than the total energy input because some energy is always dissipated, usually as heat. No device can be 100% efficient.
效率衡量的是总输入能量中有多少转移成了有用的能量输出。它可以用能量值或功率值计算，通常表示为百分比。有用的能量输出总是小于总能量输入，因为总有能量被耗散，通常是以热的形式。没有任何设备可以达到100%的效率。
Efficiency = (Useful energy output ÷ Total energy input) × 100%
For example, a filament light bulb might have an efficiency of only 10% because most of the electrical energy is transferred to thermal stores rather than light. In contrast, an LED bulb can have an efficiency of over 80%, meaning it wastes far less energy and is cheaper to run.
例如，一个白炽灯泡的效率可能只有10%，因为大部分电能转移到了热能储存而非光。相比之下，一个LED灯泡的效率可以超过80%，这意味着它浪费的能量少得多，运行成本也更低。
5. Non-renewable Energy Resources | 不可再生能源
Non-renewable energy resources are finite and will eventually run out. They include fossil fuels (coal, oil and natural gas) and nuclear fuels (uranium and plutonium). Fossil fuels were formed from the remains of dead plants and animals over millions of years. They store chemical energy that is released when they are burned. Nuclear fuels release energy from nuclear fission reactions, where atomic nuclei split to release huge amounts of heat.
不可再生能源资源储量有限，最终会用完。它们包括化石燃料（煤、石油和天然气）以及核燃料（铀和钚）。化石燃料是由数百万年来死去的动植物残骸形成的。它们储存的化学能通过燃烧释放。核燃料通过核裂变反应释放能量，原子核分裂释放出巨大的热量。
The main advantages of fossil fuels are that they are relatively cheap and the power stations can produce a constant, reliable supply of electricity. However, burning fossil fuels releases carbon dioxide (a greenhouse gas) and sulfur dioxide (which causes acid rain). Nuclear power stations do not produce carbon dioxide, but they generate radioactive waste that remains dangerous for thousands of years and requires careful storage.
化石燃料的主要优势是相对便宜，发电站可以持续、稳定地供电。然而，燃烧化石燃料会释放二氧化碳（一种温室气体）和二氧化硫（导致酸雨）。核电站不产生二氧化碳，但会产生放射性废物，这些废物在数千年内仍具有危险性，需要谨慎储存。
6. Renewable Energy Resources | 可再生能源
Renewable energy resources can be replenished in a short time scale and will not run out. The main types include solar energy (from the Sun), wind energy, wave energy, tidal energy, hydroelectric power, geothermal energy and biomass. Most of these ultimately originate from the Sun, except tidal (mainly the Moon’s gravity) and geothermal (heat from the Earth’s interior).
可再生能源可以在短时间内补充，不会耗尽。主要类型包括太阳能（来自太阳）、风能、波浪能、潮汐能、水力发电、地热能和生物质能。其中大部分最终都源于太阳，除了潮汐能（主要来自月球引力）和地热能（来自地球内部的热量）。
Renewable resources generally produce little or no greenhouse gases during operation, which makes them better for the environment. However, they often depend on weather or location, so their output can be variable. For instance, solar panels only generate electricity during daylight and are less effective on cloudy days. Wind turbines need consistent strong winds, which are not available everywhere. Building these systems can also be expensive, and they can have visual or noise impacts on local communities.
可再生能源在运行时通常产生很少或不产生温室气体，这使得它们对环境更友好。然而，它们的发电能力往往取决于天气或地理位置，因此输出可能不稳定。例如，太阳能电池板仅在白天发电，多云天效果较差。风力涡轮机需要持续强劲的风，而并非所有地方都有这样的条件。建设这些系统也可能很昂贵，并且可能对当地社区产生视觉或噪声影响。
7. Electricity Generation | 发电
Most electricity is generated by turning a turbine, which is connected to a generator. In a thermal power station (fossil fuel or nuclear), fuel is used to heat water into high-pressure steam. The steam drives a turbine, which rotates a coil of wire inside a magnetic field, inducing an electric current. This is an example of electromagnetic induction. Fossil fuel power stations burn coal, oil or gas to produce the heat, while nuclear power stations use the heat from nuclear fission.
大多数电力是通过转动与发电机相连的涡轮机产生的。在热力发电站（化石燃料或核能）中，燃料用于将水加热成高压蒸汽。蒸汽推动涡轮机，涡轮机使线圈在磁场中旋转，从而产生感应电流。这是电磁感应的一个例子。化石燃料发电站燃烧煤、石油或天然气来产生热量，而核电站则利用核裂变的热量。
In hydroelectric power stations, falling water from a reservoir directly turns the turbine, so no heating is needed. Wind turbines use the kinetic energy of moving air to spin blades connected to a generator. Solar cells (photovoltaic cells) generate electricity directly without moving parts when light energy is absorbed by semiconductor materials. In tidal and wave power systems, the movement of water is used to turn turbines.
在水力发电站中，来自水库的落水直接推动涡轮机，因此不需要加热。风力涡轮机利用流动空气的动能来旋转与发电机相连的叶片。太阳能电池（光伏电池）在半导体材料吸收光能时，无需机械运动即可直接发电。在潮汐能和波浪能系统中，水的运动被用来推动涡轮机。
8. Environmental Impact | 环境影响
The choice of energy resource has significant environmental consequences. Burning fossil fuels releases carbon dioxide, which enhances the greenhouse effect and contributes to global warming. Sulfur dioxide and nitrogen oxides can cause acid rain, damaging forests, lakes and buildings. Mining for coal and drilling for oil can destroy landscapes and lead to oil spills.
能源资源的选择对环境有重大影响。燃烧化石燃料会释放二氧化碳，增强温室效应并导致全球变暖。二氧化硫和氮氧化物会导致酸雨，破坏森林、湖泊和建筑物。煤矿开采和石油钻探会破坏景观，并可能导致石油泄漏。
Nuclear power produces very low carbon emissions during operation, but there are risks of accidents (like Fukushima or Chernobyl) and the long-term problem of radioactive waste disposal. Renewable technologies are generally cleaner, but they can still affect local ecosystems. A hydroelectric dam floods valleys, displacing wildlife and communities. Large wind farms may disrupt bird migration routes and create noise pollution. Tidal barrages can alter marine habitats. However, the overall greenhouse gas emissions over the lifetime of renewables are much lower than for fossil fuels.
核能在运行中产生的碳排放极低，但存在事故风险（如福岛或切尔诺贝利）以及放射性废物处置的长期问题。可再生能源技术通常更清洁，但仍可能影响当地生态系统。水电站大坝会淹没山谷，迫使野生动物和社区迁移。大型风力发电场可能干扰鸟类迁徙路线并产生噪音污染。潮汐坝可能会改变海洋栖息地。然而，可再生能源在整个生命周期内的温室气体排放量远低于化石燃料。
9. Sankey Diagrams | 桑基图
Sankey diagrams are a visual way of representing energy transfers and efficiency. In these diagrams, the width of each arrow is proportional to the amount of energy transferred. The input energy is shown by an arrow on the left, and the useful and wasted energy outputs are shown by arrows splitting off to the right. The total width of the output arrows equals the width of the input arrow, visually reinforcing the principle of conservation of energy.
桑基图是表示能量转移和效率的可视化方法。在这些图中，每个箭头的宽度与转移的能量成正比。输入能量由左侧的箭头表示，有用能量和浪费的能量输出由右侧分出的箭头表示。输出箭头的总宽度等于输入箭头的宽度，这在视觉上强化了能量守恒原理。
For example, a gas boiler might have a diagram showing 100 J of chemical energy input, with 70 J going to useful thermal energy in water and 30 J dissipated to the surroundings as wasted thermal energy. The efficiency can be read directly from the diagram: 70% in this case. Sankey diagrams help engineers decide where to improve a device by reducing the wasted energy arrows.
例如，一个燃气锅炉可能显示100 J的化学能输入，其中70 J转化为水中可利用的热能，30 J作为浪费的热能耗散到周围环境。效率可以直接从图中读取：在本例中为70%。桑基图帮助工程师决定如何通过减少浪费的能量箭头来改进设备。
10. Energy Calculations (with Examples) | 能量计算（含示例）
IGCSE Science requires you to perform simple energy calculations using standard equations. The most important ones involve gravitational potential energy, kinetic energy, work done and power. These are all linked by the conservation of energy.
IGCSE科学要求你使用标准方程进行简单的能量计算。最重要的方程涉及重力势能、动能、做功和功率。它们都由能量守恒联系在一起。
Gravitational potential energy: Eₚ = mgh
Here m is mass in kg, g is gravitational field strength (about 9.8 N/kg on Earth, often taken as 10 N/kg in exams), and h is height in metres. The unit of energy is the joule (J).
这里m是质量（kg），g是引力场强度（地球约为9.8 N/kg，考试中常取10 N/kg），h是高度（m）。能量单位是焦耳（J）。
Kinetic energy: Eₖ = ½ m v²
Where v is the speed in m/s. Notice the square of speed means that doubling the speed gives four times the kinetic energy.
其中v是速度（m/s）。注意速度的平方意味着，速度加倍会使动能变为原来的四倍。
Work done: W = F d
Work is done when a force F (in newtons, N) moves an object through a distance d (in metres) in the direction of the force. Work done is equivalent to energy transferred.
当力F（牛顿，N）使物体沿力的方向移动距离d（米）时，就做了功。做功等同于能量转移。
Power: P = E / t
Power is the rate of energy transfer, measured in watts (W). 1 W = 1 J/s. You can also use P = W / t.
功率是能量转移的速率，单位是瓦特（W）。1 W = 1 J/s。你也可以使用P = W / t。
A worked example: A ball of mass 0.5 kg is dropped from a height of 2.0 m. Calculate the maximum kinetic energy just before it hits the ground (ignore air resistance). Use g = 10 N/kg.
计算示例：一个质量为0.5 kg的球从2.0 m的高度落下。计算它即将撞击地面前的最大动能（忽略空气阻力）。取g = 10 N/kg。
Eₚ at top = mgh = 0.5 × 10 × 2.0 = 10 J. This is all transferred to kinetic energy, so Eₖ = 10 J. You can also find the speed: 10 = ½ × 0.5 × v² → v² = 40 → v ≈ 6.32 m/s.
顶部的Eₚ = mgh = 0.5 × 10 × 2.0 = 10 J。这全部转移为动能，所以Eₖ = 10 J。你也可以求出速度：10 = ½ × 0.5 × v² → v² = 40 → v ≈ 6.32 m/s。
Another example: an electric motor lifts a 2 kg mass through 3 m in 4 seconds. Calculate the useful power output. Use g = 10 N/kg.
另一个示例：一台电动机在4秒内将2 kg的重物提升3 m。计算有用输出功率。取g = 10 N/kg。
Work done against gravity = mgh = 2 × 10 × 3 = 60 J. Power = work done / time = 60 / 4 = 15 W. If the motor’s total input power was 20 W, its efficiency would be (15/20) × 100% = 75%.
克服重力做功 = mgh = 2 × 10 × 3 = 60 J。功率 = 做功 / 时间 = 60 / 4 = 15 W。如果电动机的总输入功率为20 W，则其效率为 (15/20) × 100% = 75%。
Practising these calculations with different scenarios will help you become confident for the IGCSE exam questions. Always show your working, check unit conversions, and remember that energy is never destroyed – just transferred into less useful forms.
在不同情景中练习这些计算将帮助你自信应对IGCSE考试题目。务必展示解题过程，检查单位换算，并牢记能量永远不会消灭——只是转移为不太有用的形式。
Published by TutorHao | Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导