单结硅太阳电池的效率为什么有个约33%的理论上限？
Why is a single-junction silicon cell capped near 33 % efficiency?
能量低于带隙的光子完全不被吸收，能量远高于带隙的光子多余部分则以热的形式浪费掉，再加上不可避免的辐射复合。把这些约束放在一起就是肖克利-奎塞尔极限，多结叠层电池通过分段吸收光谱可以突破它。
Photons below the band gap are not absorbed at all, photons far above it waste their excess as heat, and radiative recombination is unavoidable. Together these give the Shockley–Queisser limit, which tandem multi-junction cells beat by splitting the spectrum.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
W. Shockley 与 H. J. Queisser, 《Detailed Balance Limit of Efficiency of p-n Junction Solar Cells》, Journal of Applied Physics 32, 510 (1961)
W. Shockley & H. J. Queisser, 'Detailed Balance Limit of Efficiency of p-n Junction Solar Cells', Journal of Applied Physics 32, 510 (1961)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1063/1.1736034：Detailed Balance Limit of
#肖克利-奎塞尔极限 #带隙 #太阳能
电网的频率为什么必须死死稳在50赫兹附近？
Why must grid frequency be held so tightly near 50 Hz?
电网里所有交流发电机在机械上同步相连，转速对应着 50 赫兹的频率；一旦发电与用电失衡，整个电网的频率就会漂移。把频率稳定在 50 赫兹附近（如 ±0.2 赫兹），时钟、电机和同步设备才能保持一致，变压器与保护系统也才能在安全范围内工作。持续失配可能引发连锁崩溃和大停电。
AC generators across a grid are mechanically locked together and spin at a speed tied to 50 Hz; if generation and load fall out of balance, the whole grid's frequency drifts. Holding it near 50 Hz (e.g., ±0.2 Hz) keeps clocks, motors, and synchronous equipment in step and lets transformers and protective systems operate within safe limits. A sustained mismatch can cascade into blackouts.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
IEEE 电网调度标准；Kundur《电力系统稳定与控制》
IEEE grid dispatch standards; Kundur, Power System Stability and Control
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3927662W：Power system stability
#电网频率 #转动惯量 #同步
风机能不能把吹过来的风的能量全部取走？
Could a turbine extract all the energy from the wind passing through it?
不能。如果全部取走，空气就会停在叶片后面，后面的风也进不来了。用质量与动量守恒可以推出，理想风机最多只能提取来流动能的16/27，约59.3%，这就是贝兹极限，现代风机能达到约45%到50%。
No. If it took everything the air would stop dead behind the rotor and block the incoming flow. Mass and momentum conservation give a ceiling of 16/27, about 59.3 %, known as the Betz limit; real turbines reach roughly 45–50 %.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。
Betz，《风理论上可被风车利用的最大限度》，Zeitschrift fur das gesamte Turbinenwesen 26 (1920)
Betz, 'Das Maximum der theoretisch moglichen Ausnutzung des Windes durch Windmotoren', Zeitschrift fur das gesamte Turbinenwesen 26 (1920)
#贝兹极限 #动量守恒 #风能
太阳上轻松发生的聚变，为什么在地球上这么难实现？
Fusion runs easily in the Sun, so why is it so hard on Earth?
太阳靠自身巨大引力长时间约束高密度等离子体，而地球上必须用磁场或惯性压缩来代替。劳森判据要求温度、密度和约束时间的乘积足够大，同时还要控制等离子体不稳定性和材料受中子轰击的损伤。
The Sun confines dense plasma with its own immense gravity for ages, whereas on Earth magnetic fields or inertial compression must do the job. The Lawson criterion demands a large enough product of temperature, density and confinement time, while instabilities and neutron damage to materials must also be tamed.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
J. D. Lawson, 《Some Criteria for a Power Producing Thermonuclear Reactor》, Proceedings of the Physical Society B 70, 6 (1957)
J. D. Lawson, 'Some Criteria for a Power Producing Thermonuclear Reactor', Proceedings of the Physical Society B 70, 6 (1957)
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1088/0370-1301/70/1/303
#核聚变 #劳森判据 #等离子体
水电站的“水头”和“流量”，哪一个对发电更重要？
For a hydro plant, which matters more — head or flow?
水电站的功率正比于“水头”（水的落差）与“流量”（每秒水量）的乘积，所以单看哪一个都不全面。高水头站点用较小流量就能发出可观电力，而低水头河流需要很大流量才够。实际中两者都重要，但提高水头往往更划算，因为增大流量意味着更多水和更大工程。
Hydroelectric power is proportional to the product of head (the fall height) and flow (volume per second), so neither alone tells the whole story. A high-head site generates substantial power with modest flow, while a low-head river needs a large flow to match it. Both matter in practice, but raising head is often the cheaper lever because increasing flow demands far more water and infrastructure.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#水电 #水头 #功率
为什么电网喜欢用“抽水蓄能”而不是全靠电池来削峰填谷？
Why does the grid prefer pumped-storage over all-batteries for load balancing?
抽水蓄能规模巨大、寿命长、成本低，靠上下水库“存”电：用电少时把水抽到高处，高峰时放下来发电。电池虽快但贵、容量有限，更适合短时调频而非全天削峰。
Pumped storage is huge, long-lived and cheap: pump water uphill when power is plentiful, release it to generate at peaks. Batteries are fast but costly and limited in capacity, better for short bursts than all-day balancing.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#抽水蓄能 #电网 #削峰
抽水蓄能电站为什么被叫做“水做的电池”？
Why is pumped hydro storage called a battery made of water?
用电低谷时把水抽到高处水库，把电能存成重力势能；用电高峰再放水发电。往返效率大约75%到80%，响应快、寿命长，是目前规模最大的电力储能方式。
Off-peak electricity pumps water uphill, storing energy as gravitational potential, and peak demand releases it through turbines. Round-trip efficiency is about 75–80 %, with fast response and long life, making it the largest form of grid storage today.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#抽水蓄能 #重力势能 #储能
核电站为什么几乎都建在海边或大江旁？
Why are nuclear plants almost always built beside the sea or a large river?
核电站本质上是巨大的蒸汽机，热效率约三分之一，意味着每发一份电要向环境排掉两份废热。要维持冷凝器的低温端，就需要海水或江水这样近乎无限的冷源，同时也便于重型设备运输。
A reactor is essentially a giant steam engine of roughly one-third efficiency, so every unit of electricity dumps about two units of waste heat. Keeping the condenser's cold end cold needs an almost unlimited water sink, and the site also eases transport of heavy components.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#核电 #废热 #卡诺效率
地热发电靠的是多大的温差，为什么不用把地打到岩浆？
What temperature difference does geothermal power use, and why not drill to magma?
多数地热电站利用150到300℃的热水或蒸汽，与环境形成的温差已足以驱动汽轮机；中低温资源则用低沸点工质的有机朗肯循环。再往深处钻，岩石压力、高温腐蚀和成本增长远超收益。
Most plants tap water or steam at 150–300 °C, whose contrast with ambient temperature already drives a turbine, while cooler resources use organic Rankine cycles with low-boiling fluids. Drilling deeper runs into rock pressure, corrosion and costs that rise far faster than the gain.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#地热 #朗肯循环 #温差
光伏板一天里正午发电最多，一年里为什么常是春天表现最好？
Panels peak at noon each day, but why is spring often their best season?
发电量既取决于太阳辐照，也取决于组件温度。春天日照已经很强，气温还不高，加上冬季雨雪刚洗净灰尘，效率反而高于酷热的盛夏。
Output depends on both irradiance and cell temperature. In spring the sun is already strong while the air is still cool, and winter rain has just washed off dust, so efficiency beats the scorching midsummer.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Green，《第三代光伏》（2003）
Green, 'Third Generation Photovoltaics' (2003)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL6439320W：Third Generation Photov
#光伏 #温度效应 #发电量
经常用超级快充，为什么电池寿命会变短？
Why does frequent fast charging shorten battery life?
快充用大电流把锂离子强行灌入，可能使部分锂在负极表面以金属形式析出，称为“析锂”。这会永久消耗可循环的锂、增大内阻，并可能生成枝晶引发短路风险，从而缩短电池寿命和容量。更温和、温度更低、频率更低的充电可避免这些损耗。
Fast charging drives large currents that can force lithium ions to plate as metallic lithium on the anode instead of inserting into the graphite—a process called lithium plating. This permanently consumes active lithium, raises internal resistance, and may grow dendrites that risk short circuits, all of which shorten battery life and capacity. Gentler, cooler, and less frequent charging avoids these stresses.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
David Linden 与 Thomas B. Reddy 主编《Handbook of Batteries》（电池手册）
David Linden & Thomas B. Reddy (eds.), Handbook of Batteries
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-037921-3 (1995, McGraw-Hill)
#快充 #析锂 #电池寿命
什么是能量？
What is energy?
能量是物体做功能力的度量，可以表现为动能、势能、热能、光能等多种形式，并能在形式之间转化。它守恒，既不能凭空产生也不能消失。理解能量是理解几乎所有物理过程的关键。
Energy is a measure of an object's capacity to do work, appearing as kinetic, potential, thermal, light, and other forms, and convertible among them. It is conserved—never created or destroyed. Understanding energy is key to nearly every physical process.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
程守洙 江之永,《普通物理学》第七版,高等教育出版社,2016
Cheng Shouzhu and Jiang Zhiyong, General Physics, 7th ed., Higher Education Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787040429190（豆瓣书目条目: 普通物理学．上册）
#能量 #做功 #守恒
大型风力发电机为什么大多只有三片叶片？
Why do most large wind turbines have exactly three blades?
叶片越多，能捕获的风能增加很有限，却明显增加成本、重量和叶尖的空气阻力。三片在气动效率和造价之间接近最优，而且转子的惯性质量分布对称，运转时的振动比两片式小得多。
Extra blades add little captured energy but a lot of cost, weight and tip drag. Three blades sit near the optimum of efficiency versus cost and, unlike two, give a rotor whose inertia is symmetric, so vibration is far lower.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Burton，《风能手册》（第2版）
Burton, 'Wind Energy Handbook' (2nd ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL21606346W：Wind Energy Handbook（首
#风电 #气动效率 #振动
远距离输电为什么要先升到几十万伏的高压？
Why is electricity sent over long distances at hundreds of thousands of volts?
导线上的损耗是电流平方乘以电阻。输送同样的功率时，电压升高多少倍电流就降低多少倍，损耗按平方减少，所以升压十倍能把线损降到百分之一。
Line loss equals current squared times resistance. For the same power, raising the voltage by a factor cuts the current by the same factor, so the loss falls as the square — ten times the voltage means one percent of the loss.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 4 条独立证据
来源 · Source
Halliday, Resnick, Walker,《Fundamentals of Physics》第10版,Wiley,2013
David Halliday, Robert Resnick, Jearl Walker, Fundamentals of Physics, 10th ed., Wiley, 2013
独立核验依据 · Independent verification: 核验依据 3 angusrobertson.com.au
#输电 #线损 #变压器