锂离子电池为什么能又轻又高能，且需要小心管理？
Why are Li-ion batteries light and energy-dense, yet need careful management?
锂离子在充放电时于石墨负极与含锂正极之间来回嵌入脱出，锂的原子量极小、电势高，因此质量比能量突出。但过充、过放或短路会令枝晶生长、热失控，所以必须有电池管理系统。Goodenough、Whittingham 与 Yoshino 因相关贡献获 2019 年诺贝尔奖。
During charge/discharge, lithium ions shuttle between a graphite anode and a lithium-containing cathode; lithium's very low atomic weight and high potential give outstanding gravimetric energy. But overcharge, over-discharge, or short circuit can grow dendrites and trigger thermal runaway, so a battery-management system is mandatory. Goodenough, Whittingham, and Yoshino won the 2019 Nobel Prize.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
瑞典皇家科学院《2019 年诺贝尔化学奖科学背景：锂离子电池》；Reddy 主编《Linden 电池手册》(Linden's Handbook of Batteries)，第 4 版
Royal Swedish Academy of Sciences, 'Scientific Background on the Nobel Prize in Chemistry 2019: Lithium-ion Batteries'; Reddy (ed.), 'Linden's Handbook of Batteries' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-037921-3 (1995, McGraw-Hill)
#锂离子电池 #枝晶 #热失控 #比能量
集成电路是怎样把成千上万的元件做进一块芯片的？
How does an integrated circuit pack thousands of components onto one chip?
Kilby 在 1958 年用一块锗把晶体管、电阻和电容做进同一衬底，Noyce 在 1959 年提出用平面工艺和铝互连实现的硅单片集成电路。此后靠光刻把电路图形转移到硅片，再经氧化、掺杂、金属化在平面上批量做出成千上万个器件与互连。Kilby 因这项发明获 2000 年诺贝尔物理学奖（Noyce 已于 1990 年去世，未能同获）。
Kilby built a circuit in 1958 that integrated a transistor, resistor, and capacitor on one germanium substrate, and Noyce proposed the monolithic silicon IC in 1959 using the planar process with aluminum interconnects. Photolithography then transfers circuit patterns onto silicon while oxidation, doping, and metallization batch-fabricate thousands of devices and interconnects in a plane. Kilby received the 2000 Nobel Prize in Physics for the invention; Noyce had died in 1990 and could not share it.
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。
Kilby《小型化电子电路》专利(US3138743, 1959 年申请)；Noyce《半导体器件与引线结构》专利(US2981877, 1959)；2000 年诺贝尔物理学奖官方公告
Kilby, 'Miniaturized Electronic Circuits' patent (US3138743, filed 1959); Noyce, 'Semiconductor Device-and-Lead Structure' patent (US2981877, 1959); Nobel Prize in Physics 2000 official announcement
#集成电路 #光刻 #平面工艺 #Kilby
射频工程中的『阻抗匹配』为什么重要？
Why is 'impedance matching' important in radio-frequency engineering?
当信号源、传输线与负载阻抗不相等时，部分电磁波会在接口处反射，造成功率损失和信号失真。阻抗匹配使入射波被完全吸收，最大化功率传输并减少回波。
When source, line, and load impedances differ, part of the wave reflects at junctions, wasting power and distorting signals. Matching absorbs the incident wave fully, maximizing transfer and minimizing echo.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#阻抗匹配 #射频 #反射
空载变压器合闸瞬间为什么会出现远超额定值的励磁涌流？
Why does energizing an unloaded transformer produce inrush current far above its rated value?
铁心磁通是电压的积分，稳态时与电压相差九十度；若在电压过零附近合闸，磁通必须从合闸瞬间的剩磁出发单向累积，峰值可达稳态磁通两倍以上，铁心深度饱和后励磁电感急剧下降，励磁电流出现数倍甚至十几倍额定值的单向尖峰。涌流富含二次谐波和直流分量，衰减时间常数由绕组电阻与电感决定，大型变压器可持续零点几秒到数秒。为避免误跳闸，差动保护采用二次谐波闭锁或波形识别，并用合闸电阻和按剩磁选相合闸来抑制涌流幅值。
Core flux is the integral of applied voltage and lags it by ninety degrees in steady state, so closing near a voltage zero forces flux to build one-sidedly from whatever residual flux remains, peaking above twice the normal value; the core saturates deeply, magnetizing inductance collapses and current spikes to several or even more than ten times rated. The inrush is unidirectional and rich in second harmonic and DC offset, decaying with a time constant set by winding resistance and inductance, which for large units lasts from a fraction of a second to several seconds. To avoid nuisance tripping, differential protection uses second-harmonic restraint or waveform identification, while pre-insertion resistors and controlled point-on-wave closing matched to residual flux limit the peak.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Heathcote，《The J&P Transformer Book》（第13版）
Heathcote, 'The J&P Transformer Book' (13th ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL586182W：The J & P transformer bo
#励磁涌流 #铁心饱和 #二次谐波闭锁
什么是功率因数，为什么它很重要？
What is power factor and why does it matter?
功率因数是有功功率与视在功率的比值，反映电能被有效利用的程度。较低的功率因数意味着电网需要输送更多电流来传输同样的真实功率，会增加线路损耗和设备负担，因此电力公司常对低功率因数用户收费。
Power factor is the ratio of real power to apparent power, reflecting how effectively electrical energy is used. A low power factor means the grid must deliver more current to transmit the same real power, increasing line losses and equipment stress, so utilities often penalize low power factor.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#功率因数 #电能质量 #电网
晶体管是通过什么物理机制放大和开关电流信号的？
What physical mechanism lets a transistor amplify and switch current?
以双极型晶体管为例，发射结把载流子注入极薄的基区（它们在基区中是少数载流子），大部分来不及复合便扩散到集电结并被收集，因此微小的基极电流即可控制大得多的集电极电流。Bardeen 与 Brattain 在 1947 年做出点接触晶体管，Shockley 随后提出结型晶体管，三人共获 1956 年诺贝尔物理学奖，微电子时代由此开启。
In a bipolar transistor the emitter junction injects carriers into a very thin base, where they are minority carriers; most diffuse across before recombining and are collected at the collector, so a tiny base current controls a much larger collector current. Bardeen and Brattain demonstrated the point-contact transistor in 1947 and Shockley then proposed the junction transistor; the three shared the 1956 Nobel Prize in Physics, launching microelectronics.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Streetman 与 Banerjee《固态电子器件》(Solid State Electronic Devices)；Bardeen 等《晶体管》(1947, 获 1956 诺奖)
Streetman & Banerjee, 'Solid State Electronic Devices'; Bardeen, Brattain & Shockley, 'The transistor' (1947, Nobel 1956)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3512119W：Solid state electronic
#晶体管 #基极 #载流子 #放大
什么是 MOSFET？它为何成为现代电子的基石？
What is a MOSFET, and why has it become the foundation of modern electronics?
MOSFET 是金属—氧化物—半导体场效应晶体管，由栅极电压在沟道中感应出导电层来控制漏源电流，属于电压控制、功耗极低的器件。它是几乎所有微处理器和存储器中 CMOS 逻辑的基本单元，可随工艺持续微缩。
A MOSFET is a metal-oxide-semiconductor field-effect transistor whose gate voltage induces a conducting channel to control drain-source current; it is voltage-controlled and very low power. It is the building block of CMOS logic in virtually all microprocessors and memories and scales well with fabrication advances.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
电气与电子工程师协会（IEEE）电子器件学会；Streetman & Banerjee《固态电子器件》
IEEE Electron Devices Society; Streetman & Banerjee, 'Solid State Electronic Devices'
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL11000079M：2000 IEEE Electron Dev
#MOSFET #场效应晶体管 #CMOS #集成电路
什么是电磁兼容性（EMC）？
What is electromagnetic compatibility (EMC)?
电磁兼容性是指电子设备在电磁环境中既能正常工作，又不对其他设备产生不可接受的干扰的能力。它涉及屏蔽、滤波、接地和合理布线，是现代电子产品认证的重要内容。
Electromagnetic compatibility is the ability of electronic equipment to function correctly in an electromagnetic environment without causing unacceptable interference to other devices. It involves shielding, filtering, grounding, and careful layout, and is a key part of modern product certification.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#电磁兼容 #干扰 #屏蔽
发光二极管(LED)和普通白炽灯的发光原理有何不同？
How does an LED's light-emitting physics differ from an incandescent bulb?
白炽灯靠电流把灯丝加热到高温、以热辐射发光，绝大部分电能变成热；LED 则是电子与空穴在半导体 pn 结复合时把能量直接转成光子，属于电致发光，发热少、光效高得多。赤崎勇、天野浩与中村修二研制出高效蓝光 LED，使白光半导体照明成为可能，三人共获 2014 年诺贝尔物理学奖。
An incandescent bulb heats a filament until it glows by thermal radiation, wasting most of the energy as heat; an LED instead converts energy directly into photons when electrons and holes recombine at a semiconductor p-n junction—electroluminescence, with far less heat and much higher efficacy. Akasaki, Amano, and Nakamura developed the efficient blue LED that made white solid-state lighting possible and shared the 2014 Nobel Prize in Physics.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Nakamura 等《蓝光 LED 与激光》(1990s)；Holonyak & Bevacqua,《COHERENT (VISIBLE) LIGHT EMISSION FROM Ga(As1− x P x ) JUNCTIONS》,Applied Physics Letters,1962 (DOI: 10.1063/1.1753706)；2014 诺贝尔奖委员会
Nakamura et al., 'Blue LEDs and lasers' (1990s); Holonyak & Bevacqua, 'COHERENT (VISIBLE) LIGHT EMISSION FROM Ga(As1− x P x ) JUNCTIONS', Applied Physics Letters, 1962, DOI: 10.1063/1.1753706; Nobel Committee 2014
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1063/1.1753706
#LED #pn结 #电致发光 #中村修二
太阳能电池的效率上限是由什么决定的，这就是 Shockley-Queisser 极限吗？
What sets the efficiency ceiling of solar cells—is it the Shockley-Queisser limit?
光子能量若高于半导体带隙，多余部分以热的形式损失；低于带隙的光子又无法激发电子，因此单结电池的理论效率约 33%。Shockley 与 Queisser 在 1961 年给出这一根本极限，多结和聚光技术用来逼近或突破它。
Photons with energy above the semiconductor bandgap waste the excess as heat, while photons below it cannot excite electrons, so a single-junction cell tops out near 33%. Shockley and Queisser derived this fundamental limit in 1961; multijunction and concentrator designs approach or exceed it.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Shockley, W., Queisser, H.J.,《Detailed Balance Limit of Efficiency of p-n Junction Solar Cells》, Journal of Applied Physics, 1961 (DOI: 10.1063/1.1736034)；Green《太阳能电池原理》
Shockley, Queisser, 'Detailed Balance Limit of Efficiency of p-n Junction Solar Cells', Journal of Applied Physics, 1961, DOI: 10.1063/1.1736034; Green, 'Solar Cells'
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1063/1.1736034
#太阳能电池 #带隙 #Shockley-Queisser #热损失
超导体为什么能让 MRI 磁体零电阻运行？
Why can a superconductor run an MRI magnet with zero resistance?
某些材料降到临界温度以下时电阻突变为零，且能承载巨大持续电流；BCS 理论用电子配对（库珀对）解释这一现象。液氦冷却的铌钛超导线圈因此能长期维持强磁场供 MRI 使用。Onnes 1911 年发现超导，Bardeen、Cooper、Schrieffer 获 1972 年诺贝尔奖。
Below a critical temperature some materials drop to zero resistance and carry huge persistent currents; BCS theory explains this via electron pairing (Cooper pairs). Liquid-helium-cooled niobium-titanium coils thus sustain strong MRI magnetic fields indefinitely. Onnes discovered superconductivity in 1911; Bardeen, Cooper, and Schrieffer won the 1972 Nobel Prize.
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。
Bardeen、Cooper 与 Schrieffer《BCS 理论》(Physical Review, 1957)；Onnes《汞的超导》(1911)
Bardeen, Cooper & Schrieffer, 'Theory of Superconductivity' (Phys Rev, 1957); Onnes, 'Superconductivity of mercury' (1911)
#超导体 #BCS理论 #库珀对 #MRI磁体
光纤通信是靠什么实现超低损耗远距离传输的？
How does optical fiber achieve ultra-low-loss long-distance transmission?
高纯石英光纤把光约束在纤芯内以全反射传播，并在 1550 nm 附近有极低的本征吸收窗口；配合掺铒光纤放大器可数千公里不靠电信号再生。Kao 在 1966 年论证低损耗光纤可行，获 2009 年诺贝尔奖。
High-purity silica fiber confines light in the core by total internal reflection and has a very low intrinsic-loss window near 1550 nm; erbium-doped fiber amplifiers let signals span thousands of kilometers without electrical regeneration. Kao proved low-loss fiber feasible in 1966, winning the 2009 Nobel Prize.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Kao & Hockham,《Dielectric-fibre surface waveguides for optical frequencies》,Proceedings of the Institution of Electrical Engineers,1966 (DOI: 10.1049/piee.1966.0189)；Keck 等《低损耗光纤》(1970)；IEEE 光子学会
Kao & Hockham, 'Dielectric-fibre surface waveguides for optical frequencies', Proceedings of the Institution of Electrical Engineers, 1966, DOI: 10.1049/piee.1966.0189; Keck et al., 'Low-loss fiber' (1970); IEEE Photonics Society
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1049/piee.1966.0189
#光纤 #全反射 #掺铒放大 #Kao
抽水蓄能电站是怎么把"多余的电"存起来的？
How does a pumped-storage plant store surplus electricity?
抽水蓄能是规模最大的电网储能方式：深夜或风电大发时电力过剩、电价低，电站用电把下水库的水抽到高处，把电能变成水的重力势能；白天用电高峰时再放水，让水流推动水轮机发电。往返效率约70%到80%，损耗来自水泵水轮机的摩擦和蒸发。它响应快、一次可存数百万度电，是调峰、调频和支撑新能源消纳的主力。
Pumped storage is the grid's largest energy-storage technology: when power is surplus and cheap — overnight or when wind peaks — it uses electricity to pump water from the lower reservoir up to the upper one, storing energy as gravitational potential energy; at daytime peak, the water flows back down through turbines to generate. Round-trip efficiency is roughly 70-80%, with losses to pump-turbine friction and evaporation. It responds within minutes, holds millions of kWh, and is the backbone of peak shaving, frequency regulation, and renewable integration.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
NREL 美国国家可再生能源实验室；Twidell & Weir《可再生能源资源》；IAEA 核安全标准
NREL (National Renewable Energy Laboratory); Twidell & Weir, Renewable Energy Resources; IAEA Safety Standards
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL5479870W：Renewable energy resour
#抽水蓄能 #储能 #调峰
什么是电容器，它能做什么？
What is a capacitor and what does it do?
电容器是由两块导体和中间的绝缘介质组成的元件，能够储存和释放电荷。它在电路中用于滤波、耦合信号、定时以及瞬间提供大电流。
A capacitor is a component of two conductors separated by an insulating dielectric that can store and release electric charge. In circuits it is used for filtering, signal coupling, timing, and delivering brief bursts of high current.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#电容器 #储能 #滤波
电网继电保护的『选择性』为什么要靠时间级差来实现？
Why does power-system protection rely on time grading to achieve selectivity?
选择性要求只切除故障所在的最小区段，让上级电源和无关线路继续供电。定时限或反时限过流保护无法仅凭电流判断故障究竟在本级还是下级，于是越靠电源侧的保护设置越长的动作延时（典型级差 0.3–0.5 s），下级先动作、上级只在下级失灵时作为后备跳闸。缺点是靠近电源处故障电流最大而延时最长，因此重要线路改用距离保护、差动保护或纵联通道实现快速的分区选择，把时间级差留给后备保护。
Selectivity means tripping only the smallest zone containing the fault so healthy feeders keep supplying load. Definite- or inverse-time overcurrent relays cannot tell from current alone whether a fault lies in their own zone or downstream, so relays nearer the source get progressively longer delays, typically 0.3–0.5 s per step, letting the downstream device clear first while the upstream one trips only as backup. The drawback is that the largest fault currents sit where delays are longest, so important circuits use distance, differential or pilot-channel protection for fast unit selectivity and keep time grading for backup duty.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Blackburn 与 Domin，《Protective Relaying: Principles and Applications》（第4版）
Blackburn & Domin, 'Protective Relaying: Principles and Applications' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781498760003 (2014)
#继电保护 #选择性 #时间级差
什么是半导体，二极管有何作用？
What is a semiconductor and what does a diode do?
半导体是导电能力介于导体和绝缘体之间的材料，硅是最常见的半导体。二极管是一种只允许电流单向通过的半导体器件，常用于整流、保护和信号处理。
A semiconductor is a material whose conductivity lies between that of a conductor and an insulator, with silicon being the most common. A diode is a semiconductor device that lets current pass in only one direction, used for rectification, protection, and signal processing.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#半导体 #二极管 #整流
变压器是如何利用电磁感应改变交流电压的？
How does a transformer use electromagnetic induction to change AC voltage?
变压器的一次、二次绕组绕在同一铁芯上，一次侧交流电流产生交变磁通，按法拉第电磁感应定律在二次侧感应出电动势。电压比等于匝数比，即 V_s/V_p = N_s/N_p，可实现升压或降压。
A transformer's primary and secondary windings share a magnetic core; AC in the primary creates an alternating flux that induces an EMF in the secondary by Faraday's law. The voltage ratio equals the turns ratio, V_s/V_p = N_s/N_p, enabling step-up or step-down.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
电气与电子工程师协会（IEEE）IEEE C57 系列标准；Fitzgerald & Kingsley《电机学》
IEEE Std C57 series; Fitzgerald & Kingsley, 'Electric Machinery'
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780070211407 (1992)
#变压器 #电磁感应 #匝数比 #法拉第定律
"智能电网"比普通电网智能在哪里？
What makes a "smart grid" smarter than a regular grid?
传统电网是发-输-配的单向供电，电厂跟着负荷走；智能电网则在发电、输电、配电、用电各环节装上传感器和双向通信，让电网实时感知状态并自动调配。它能接入海量的分布式光伏、风电和电动车充电桩，通过需求响应调节负荷（比如引导电动车错峰充电），停电时自动隔离故障区段并快速自愈。就像给电网装上大脑和神经，在新能源波动越来越大的时代维持供需平衡。
A conventional grid is one-way — plants follow the load. A smart grid layers sensors and two-way communication across generation, transmission, distribution, and consumption so the network senses its state and dispatches automatically. It integrates massive rooftop solar, wind, and EV chargers, shifts load through demand response (such as guiding EV charging to off-peak hours), and isolates faulted sections to self-heal after outages. It is like giving the grid a brain and nervous system to balance supply and demand in an era of increasingly volatile renewables.
难度 进阶 · 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
#智能电网 #双向通信 #需求响应
压电材料为什么能既做传感器又做驱动器？
Why can piezoelectric materials act as both sensors and actuators?
压电效应指在机械应力下晶体产生电荷（正压电），反之施加电场会产生形变（逆压电），居里兄弟在 1880 年发现。同一片材料受力可发电、通电可振动，因此广泛用于点火器、超声探头和喷墨头。
The piezoelectric effect yields electric charge under mechanical stress (direct) and strain under an electric field (converse), discovered by the Curie brothers in 1880. The same element generates voltage when stressed and vibrates when driven, so it serves in igniters, ultrasound probes, and inkjet heads.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
Curie 兄弟《压电效应》(1880)；IEEE 超声铁电与频率控制学会
Curie brothers, 'Piezoelectricity' (1880); IEEE Ultrasonics, Ferroelectrics & Frequency Control Society
#压电 #逆压电 #居里兄弟 #传感器
锂离子电池为什么能成为主流充电电池？
Why have lithium-ion batteries become the dominant rechargeable battery?
锂离子电池靠锂离子在正负极间往返嵌入脱出来储放电能，能量密度高、自放电低、寿命长且无记忆效应，因此广泛用于手机、电动车和储能系统。
Li-ion cells store energy by shuttling lithium ions between electrodes; they offer high energy density, low self-discharge, and long life with no memory effect, powering phones, EVs, and storage.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Linden & Reddy，《林登电池手册》（第4版）
Linden & Reddy, 'Lindens Handbook of Batteries' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-07-037921-3 (1995, McGraw-Hill)
#锂电池 #能量密度 #充电
雷达是怎样用电磁波『看见』远处物体的？
How does radar 'see' distant objects with electromagnetic waves?
雷达发射脉冲电磁波，遇到目标后部分能量反射回来，通过测量往返时间算出距离、用回波的多普勒频移算出速度。Watson-Watt 在二战前把这一原理发展成实用防空雷达。
Radar emits pulsed electromagnetic waves; part reflects off a target and returns, and the round-trip time gives range while the Doppler shift of the echo gives velocity. Watson-Watt developed this into practical air-defense radar before WWII.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Skolnik《雷达系统导论》(Introduction to Radar Systems)，第 3 版；Watson-Watt《用无线电方法探测与定位飞机》备忘录(英国空军部, 1935)
Skolnik, 'Introduction to Radar Systems' (3rd ed.); Watson-Watt, 'Detection and Location of Aircraft by Radio Methods' memorandum (UK Air Ministry, 1935)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL221640W：Introduction to radar sy
#雷达 #多普勒 #脉冲 #回波
交流感应电动机为什么不需要电刷也能转动？
Why can an AC induction motor spin without brushes?
定子绕组产生旋转磁场，转子导体因相对切割磁感线感应出电流，进而受安培力被『拖着』跟随旋转，转速略低于磁场转速（转差）。这种结构简单坚固、免维护，是工业最常用的电机。特斯拉在 1887 年发明多相感应电机。
The stator's windings create a rotating magnetic field; currents induced in the rotor conductors by relative motion produce Ampere forces that drag the rotor along, at a speed slightly below the field (slip). Robust and brushless, it is industry's most common motor. Tesla invented the polyphase induction motor in 1887.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Fitzgerald 等《电机学》(Electric Machinery)；Tesla《多相交流电机》(1888)
Fitzgerald et al., 'Electric Machinery'; Tesla, 'A New System of Alternating Current Motors' (1888)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780070211407 (1992)
#感应电机 #旋转磁场 #转差 #特斯拉
麦克斯韦方程组和赫兹的实验为什么是无线通信的基础？
Why are Maxwell's equations and Hertz's experiment the basis of wireless communication?
麦克斯韦在 1865 年预言电磁波存在并给出其速度等于光速，赫兹在 1887 年用实验产生并检测到无线电波，证实预言。这之后马可尼等人才能把电磁波用于跨距通信。
Maxwell predicted in 1865 that electromagnetic waves exist and travel at light speed; Hertz generated and detected radio waves in 1887, confirming it. Only then could Marconi and others use them for distance communication.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Maxwell《电磁场的动力学理论》(Philosophical Transactions, 1865)；Hertz《电波》(Electric Waves, 1893 英译本)
Maxwell, 'A Dynamical Theory of the Electromagnetic Field' (Philosophical Transactions, 1865); Hertz, 'Electric Waves' (English translation, 1893)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.5479/sil.423156.39088007130693：A dynamica
#麦克斯韦 #赫兹 #电磁波 #无线通信
远距离输电为什么要把电压升得很高？
Why is voltage raised very high for long-distance power transmission?
输送一定功率时，电压越高电流越小，而线路损耗与电流平方成正比，因此高压能大幅降低发热损耗。所以电站先用变压器升压，到用户端再降压。
For a given power, higher voltage means lower current, and line loss grows with the square of current—so high voltage sharply cuts heating loss. Plants step up, then step down near users.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#输电 #高压 #损耗
工业和大楼供电为什么常用三相电？
Why is three-phase power common for industry and buildings?
三相电由三组相位相差120度的交流组成，传输同样功率可用更细的导线，且电动机运行更平稳、起动转矩大。单相只是其中一相，适合家庭小负荷。
Three-phase power uses three AC waveforms 120° apart; it delivers the same power with thinner wires and gives motors smooth, high-starting-torque operation. Single-phase is one leg, for small home loads.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#三相电 #相位 #电动机
什么是功率因数？电网为什么要求它尽量接近 1？
What is power factor, and why do power grids require it to be close to 1?
功率因数 = 有功功率 / 视在功率 = cos φ，反映电能被有效利用的程度。功率因数低意味着传输相同有功功率需要更大电流，从而增加线路损耗和电压降落，因此供电公司会对低功率因数用户加收费用。
Power factor equals real power divided by apparent power, or cos φ, reflecting how effectively electric energy is used. A low power factor means larger current for the same real power, raising line losses and voltage drop, so utilities penalize low-power-factor customers.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04 · 2 条独立证据
来源 · Source
电气与电子工程师协会（IEEE）IEEE Std 1459；Saadat《电力系统分析》
IEEE Std 1459; H. Saadat, 'Power System Analysis'
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780070612938 (1994) · 核验依据 2 ISBN 9780665590955 (2002)
#功率因数 #无功功率 #视在功率 #电网
什么是三相电，为什么工业中常用它？
What is three-phase power and why is it common in industry?
三相电由三个相位相差120度的交流电压组成，能平稳地提供动力。它比单相电输电效率更高、电机运行更平稳，因此广泛用于工厂和大型设备。
Three-phase power consists of three AC voltages offset by 120 degrees, delivering power smoothly. It transmits energy more efficiently and runs motors more steadily than single-phase power, so it is widely used in factories and large equipment.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#三相电 #电机 #输电效率
为什么变压器能改变电压，而且是交流电的"专属设备"？
Why can a transformer change voltage, and only for AC?
变压器利用电磁感应：初级线圈通入交流电，在铁芯中产生交变磁通，次级线圈切割磁通感应出电压。电压比等于匝数比，想要多少伏就按比例绕多少圈。它不能用于直流，因为恒定电流不产生变化的磁通，次级就没有感应电动势。电网正是靠层层变压器把电压升上去输送、再降下来使用，理想情况下功率守恒：升压的同时电流同比例减小。
A transformer works by electromagnetic induction: AC in the primary winding creates alternating flux in the core, which induces voltage in the secondary winding. The voltage ratio equals the turns ratio, so you wind as many turns as you need volts. It cannot work on DC, because steady current makes no changing flux and hence no induced EMF. The grid is a ladder of transformers stepping voltage up for transmission and down for use; ideally power is conserved, so higher voltage means proportionally lower current.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#变压器 #电磁感应 #匝数比
摩尔定律说的是什么，今天还成立吗？
What does Moore's law say, and does it still hold?
Moore 在 1965 年观察到集成电路上的元件数大约每年翻一番，1975 年他把节奏修正为约每两年翻一番，这一趋势长期指引了芯片性能与成本走势。进入纳米尺度后受物理极限与光刻成本制约，密度增速明显放缓，产业转向多核、专用加速器和先进封装来延续性能提升。
Moore observed in 1965 that the number of components on an integrated circuit roughly doubled every year, and in 1975 he revised the pace to about every two years; the trend long guided chip performance and cost. At nanometer scales, physical limits and lithography costs have clearly slowed density scaling, so the industry now leans on multicore designs, specialized accelerators, and advanced packaging.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Moore《让电路元件更多》(Electronics, 1965)；英特尔(Intel)《摩尔定律》
Moore, 'Cramming more components onto integrated circuits' (Electronics, 1965); Intel, 'Moore's Law'
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL13379258W：Cramming more componen
#摩尔定律 #晶体管密度 #集成电路 #纳米
光纤是怎样用光来传数据的？
How does an optical fiber carry data using light?
光纤是极细的玻璃或塑料丝，利用全反射把光信号限制在纤芯内长距离传输，几乎不受电磁干扰、损耗极低，因此能高速、大容量地传送电话和互联网数据。
An optical fiber is a thin glass or plastic thread that traps light by total internal reflection and carries it far with tiny loss and no electromagnetic interference, enabling high-speed, high-capacity data.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
《通信原理》（樊昌信，国防工业出版社）
A Mathematical Theory of Communication, Shannon (Bell System Technical Journal)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787563511747（豆瓣书目条目: 通信原理）
#光纤 #全反射 #通信
什么是三相交流电？为什么电力传输普遍采用三相制？
What is three-phase AC power, and why is three-phase used almost universally for power transmission?
三相交流电由幅值相等、相位互差120°的三个正弦电压组成。它在传输相同功率时比单相更省导线材料，且瞬时功率恒定、能自然驱动三相感应电动机，因此成为电网标准。
Three-phase AC consists of three sinusoidal voltages of equal magnitude spaced 120° apart. For the same power it needs less conductor material than single-phase, delivers constant instantaneous power, and naturally runs three-phase induction motors, making it the grid standard.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
电气与电子工程师协会（IEEE）IEEE Std 141（红皮书）；B.M. Weedy《电力系统》
IEEE Std 141 (Red Book); B.M. Weedy, 'Electric Power Systems'
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2737833W：Electric power systems（
#三相电 #交流电 #输电 #相位差
什么是运算放大器？理想运放在负反馈下的两条“黄金法则”是什么？
What is an operational amplifier, and what are the two golden rules of an ideal op-amp under negative feedback?
运算放大器是高增益差分放大器，放大两输入端之差。在负反馈下可近似为：两输入端电流为零、两输入端之间电压差为零（虚短）。据此可构成放大器、滤波器、积分器等电路。
An operational amplifier is a high-gain differential amplifier that amplifies the difference between its two inputs. Under negative feedback the ideal op-amp obeys: (1) no current enters the input terminals, and (2) the voltage difference between the inputs is zero (virtual short). From these rules come amplifiers, filters, and integrators.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
电气与电子工程师协会（IEEE）；Sedra & Smith《微电子电路》
IEEE; Sedra & Smith, 'Microelectronic Circuits'
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL17770472W：Microelectronic circui
#运算放大器 #负反馈 #虚短 #差分放大
电气设备的『接地』起什么保护作用？
What protective role does 'grounding' play for electrical equipment?
接地把设备金属外壳连到大地，一旦内部火线碰壳，故障电流经低阻通路流入大地并触发断路器跳闸，避免人触电。它还能泄放雷击和静电。
Grounding connects the metal case to earth so a fault current flows safely to ground and trips the breaker instead of shocking a person; it also dissipates lightning and static.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#接地 #触电 #保护
交流电和直流电最根本的区别是什么？
What is the fundamental difference between AC and DC?
直流电方向和大小基本不变，电池就是直流；交流电的方向和大小周期性反转，家用插座就是交流。交流易于用变压器升降压、远距离输电更经济，所以电网普遍用交流。
DC flows in one steady direction, as from batteries; AC reverses direction periodically, as in wall outlets. AC is easily stepped up or down by transformers and is cheaper to transmit far, so grids use AC.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#交流电 #直流电 #电网
变压器是如何改变电压的？
How does a transformer change voltage?
变压器利用电磁感应，通过两个匝数不同的线圈来升高或降低交流电的电压。输入线圈和输出线圈的匝数比决定了电压变化的倍数，变压器几乎不消耗能量。
A transformer uses electromagnetic induction through two coils of different turn counts to raise or lower alternating voltage. The ratio of turns between the input and output coils determines the voltage change, and the device itself wastes almost no energy.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#变压器 #电磁感应 #电压
变压器为什么能改变电压？
Why can a transformer change voltage?
变压器利用电磁感应：原边线圈的交变电流产生交变磁场，穿过副边线圈感应出电压。匝数多的线圈电压高，匝数少的电压低，因此可实现升压或降压而不改变频率。
A transformer uses electromagnetic induction: alternating current in the primary makes a changing magnetic field that induces voltage in the secondary. More turns means higher voltage, stepping up or down without changing frequency.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Alexander & Sadiku,《电路基础》(Fundamentals of Electric Circuits),McGraw-Hill
Alexander & Sadiku, Fundamentals of Electric Circuits, McGraw-Hill
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787111470885（豆瓣书目条目: 电路基础）
#变压器 #电磁感应 #电压
半导体二极管为什么具有单向导电性？
Why does a semiconductor diode conduct current in only one direction?
二极管的核心是 PN 结，其两侧形成耗尽层。正向偏置时耗尽层变窄、电流得以通过；反向偏置时耗尽层变宽、阻挡载流子，因此只在一个方向导通。
The heart of a diode is the PN junction, which forms a depletion region. Forward bias narrows this region so current flows, while reverse bias widens it and blocks carriers, so conduction occurs in only one direction.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
电气与电子工程师协会（IEEE）；Neamen《半导体物理与器件》
IEEE; Neamen, 'Semiconductor Physics and Devices'
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL3344363W：Semiconductor physics a
#PN结 #二极管 #单向导电 #耗尽层
什么是电路中的电阻？
What is electrical resistance in a circuit?
电阻是导体对电流流动的阻碍作用，单位是欧姆。根据欧姆定律，电压等于电流乘以电阻，电阻越大，在同样电压下通过的电流越小。
Resistance is the opposition a conductor offers to the flow of current, measured in ohms. By Ohm's law, voltage equals current times resistance, so a larger resistance passes less current for the same applied voltage.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#电阻 #欧姆定律 #电压
电路里的『短路』为什么很危险？
Why is a 'short circuit' in a circuit dangerous?
短路是火线与零线或地之间出现极低电阻的意外通路，电流会骤增到极大，产生大量热和电弧，可能烧毁设备甚至引发火灾，所以电路都要装保险或断路器。
A short circuit is an unintended low-resistance path that lets current surge, generating intense heat and arcs that can destroy equipment or start fires—so circuits need fuses or breakers.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#短路 #电流 #保护
欧姆定律说的是什么关系？
What relationship does Ohm's law describe?
欧姆定律指出，在常温下的导体中，电压等于电流乘以电阻（V=IR）。电压越高或电阻越小，电流越大，是电路分析与设计的基本公式。
Ohm's law states that voltage equals current times resistance (V = IR) for many conductors. Higher voltage or lower resistance gives more current—the basic rule of circuit analysis.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#欧姆定律 #电压 #电流
同样是铜线，为什么细的只能带小电流，粗一点就能多带？
With the same copper, why can a thin wire carry only a small current while a thicker one carries much more?
导线的发热功率等于电流平方乘以电阻，而电阻与截面积成反比，所以截面减半时同一电流的发热大约翻倍；散热能力却大致只随表面积增长，远慢于发热的增加。载流量就是让导体稳定温度不超过绝缘允许温度（例如 70 ℃ 或 90 ℃）的最大电流，规范据此按截面、绝缘材料、敷设方式和环境温度给出查表值，多根线共管或高温环境还要乘折减系数。这也是为什么长期过载会先让绝缘老化碳化再引发短路火灾，以及断路器额定值必须与导线截面配套，而不能只看电器功率。
Heating in a conductor equals current squared times resistance, and resistance is inversely proportional to cross-section, so halving the area roughly doubles the heat at the same current, while heat rejection grows only with surface area. Ampacity is the current at which steady conductor temperature just reaches the insulation rating, such as 70 or 90 °C, and codes tabulate it by size, insulation type, installation method and ambient temperature, with derating factors when several cables share a conduit or surroundings are hot. That is why sustained overload first ages and carbonizes insulation before causing a short-circuit fire, and why a breaker must be matched to the conductor size rather than chosen from appliance ratings alone.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-04
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NFPA 70《National Electrical Code》表 310.16（导体载流量）
NFPA 70, 'National Electrical Code', Table 310.16 (conductor ampacities)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781455911301 (2022)
#载流量 #焦耳热 #导线选型
电池是怎样储存电能的？
How does a battery store electrical energy?
电池通过内部化学反应把化学能转化为电能。当电池放电时，化学反应释放电子形成电流；充电时则反向进行，把电能重新变回化学能储存起来。
A battery stores energy by means of internal chemical reactions that convert chemical energy into electricity. During discharge the reactions release electrons as current, and charging reverses the process, storing electrical energy back as chemical energy.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#电池 #化学能 #储能
电流是什么？
What is electric current?
电流是电荷在导体中的定向流动，通常用安培来计量。电池、发电机和太阳能板都可以提供推动电荷流动的电动势。
Electric current is the directed flow of electric charge through a conductor, measured in amperes. Batteries, generators, and solar panels all provide the electromotive force that drives charge to flow.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
邱关源 主编 罗先觉 修订,《电路》第5版,高等教育出版社,2006
Qiu Guanyuan ed., Circuit, 5th ed., Higher Education Press, 2006
#电流 #电荷 #安培