无线电、可见光和 X 光本质上有什么共同点？
What do radio waves, visible light, and X-rays have in common at heart?
它们都是电磁波，只是频率与波长不同。无线电波长、频率低，X 光波长短、频率高；整个排列就是电磁波谱，由麦克斯韦理论统一描述。
They are all electromagnetic waves differing only in frequency and wavelength. Radio waves are long and low-frequency, X-rays short and high-frequency; the whole ordering is the electromagnetic spectrum described by Maxwell's theory.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电磁波谱 #频率 #波长
麦克斯韦方程组描述了什么？
What do Maxwell's equations describe?
麦克斯韦方程组用四个方程统一描述了电场、磁场及其与电荷和电流的关系，并预言了电磁波的存在。它是经典电磁学的基石，也奠定了现代通信的理论基础。
Maxwell's equations use four relations to describe electric and magnetic fields and their links to charges and currents, predicting electromagnetic waves. They are the foundation of classical electromagnetism and modern communications.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#麦克斯韦方程 #电磁场 #电磁波
麦克斯韦方程组统一了哪两件事，并预言了什么？
What two things do Maxwell's equations unify, and what did they predict?
麦克斯韦方程把电、磁与光统一成同一种电磁现象，并预言变化的电场会产生磁场、变化的磁场产生电场，从而电磁波可在真空中以光速传播。
Maxwell's equations unify electricity, magnetism, and light as one electromagnetic phenomenon, and predict that changing electric fields make magnetic fields and vice versa, so electromagnetic waves travel through vacuum at the speed of light.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#麦克斯韦方程 #电磁波 #光速
为什么强磁铁在厚铜管里会慢慢下落？
Why does a strong magnet fall slowly through a thick copper tube?
磁铁下落时，铜管内的磁通持续变化，管壁中因此产生一圈圈闭合的感应电流，叫涡电流。根据楞次定律，涡电流的磁场总是反抗磁铁的运动，产生向上的阻力，与重力平衡后磁铁便以很低的恒定速度匀速下落。磁悬浮列车和电梯的电磁制动利用的正是这种涡流阻力，感应加热炉则反过来利用涡流在金属内部发热来熔化金属。
As the magnet falls, the changing flux induces closed loops of current — eddy currents — in the copper walls. By Lenz's law these currents create a field that opposes the motion, giving an upward drag that balances gravity, so the magnet settles into a slow constant fall. Electromagnetic brakes on maglev trains and elevators exploit exactly this drag, while induction furnaces run it in reverse, using eddy-current heating to melt metal.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（感应电流）
The Feynman Lectures on Physics, Vol. 2 (induced currents)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#涡电流 #楞次定律 #电磁制动
为什么电容器让交流电"通过"，却把直流电挡住？
Why does a capacitor pass alternating current but block direct current?
电容器靠两极板间的电场储存能量。面对交变电压，极板上的电荷不断增减，导线上便持续有电流流进流出，看起来交流"穿过"了电容器；而面对恒定的直流电压，电容器充电完成后电流就降为零。电容器对交流的阻碍叫容抗，与频率成反比，电感则相反、感抗与频率成正比。这两者与电阻一起，共同决定交流电路中电流与电压的相位关系。
A capacitor stores energy in the field between its plates. Under alternating voltage the plates continuously charge and discharge, so current keeps flowing through the wires and effectively "passes" the capacitor; with steady DC the current dies once charging is complete. A capacitor's AC opposition, capacitive reactance, falls with frequency, while an inductor's inductive reactance rises with it. Together with resistance, these set the phase relationship between current and voltage in AC circuits.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（交流电路）
The Feynman Lectures on Physics, Vol. 2 (AC circuits)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#容抗 #感抗 #相位
为什么说麦克斯韦方程组是物理学最重要的方程之一？
Why are Maxwell's equations counted among the most important in all of physics?
四个方程把电学、磁学和光学统一成一个理论：高斯定律描述电荷如何产生电场，磁场无源说明不存在孤立的磁单极，法拉第定律指出变化的磁场如何激发电场，安培-麦克斯韦定律则说明电流和变化的电场如何产生磁场。麦克斯韦由此预言了电磁波并算出其速度等于光速，爱因斯坦又在此基础上创立了狭义相对论。从无线电到智能手机，几乎所有现代技术都建立在这组方程之上。
Four equations unify electricity, magnetism and optics: Gauss's law tells how charges create electric fields, the no-monopole law says magnetic field lines have no sources, Faraday's law shows how changing magnetic fields generate electric ones, and the Ampère–Maxwell law explains how currents and changing electric fields create magnetic fields. Maxwell predicted electromagnetic waves and found their speed equals light's, and Einstein built special relativity on the same ideas. Nearly all modern technology, from radio to smartphones, rests on these equations.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（麦克斯韦方程组）
The Feynman Lectures on Physics, Vol. 2 (Maxwell's equations)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#麦克斯韦方程组 #电磁波 #统一
超导体除了零电阻，还有什么更奇特的性质？
Besides zero resistance, what stranger property do superconductors have?
超导体会完全排斥内部磁场（迈斯纳效应），使磁体悬浮其上。这不只是“没有电阻”，而是主动把磁通排出体外，是区别于理想导体的本质特征。
A superconductor expels magnetic field from its interior (the Meissner effect), letting a magnet levitate above it. This is not just zero resistance but an active pushing-out of flux, what truly distinguishes it from a perfect conductor.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#迈斯纳效应 #超导 #磁悬浮
超导体是如何把磁场“排出”自身的？
How do superconductors expel magnetic fields from themselves?
低于临界温度后，超导体内部感应出表面屏蔽电流，使磁感应强度在体相中降为零，这一现象叫迈斯纳效应。Meissner 与 Ochsenfeld 于 1933 年用实验证实，它说明超导态是真正的抗磁态而非单纯零电阻。
Below a critical temperature a superconductor develops surface screening currents that cancel the interior magnetic field, driving it to zero—the Meissner effect. Meissner and Ochsenfeld demonstrated this in 1933, showing superconductivity is a true diamagnetic state, not merely zero resistance.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04 · 2 条独立证据
来源 · Source
Meissner 与 Ochsenfeld 1933 年论文；Kittel《固体物理导论》
Meissner & Ochsenfeld (1933); Kittel, Introduction to Solid State Physics
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780471490241 (2005) · 核验依据 2 ISBN 9780030839931 (2022)
#迈斯纳效应 #超导体 #抗磁性
人类从没到过恒星，怎么知道太阳由什么元素组成？
Humans have never visited a star — how do we know what elements the Sun contains?
每种元素的原子都只能吸收或发射特定波长的光，形成一套特征谱线，如同指纹。把太阳光经过棱镜或光栅分光后，会看到一道道暗的吸收线——那是太阳外层大气中的原子吸收了对应波长的光。分析这些吸收线的波长和强弱，就能确定元素种类与丰度。1868年日食期间，科学家正是靠光谱在地球上看到了氦——它先在天上被发现，之后才在地球上找到。
Every element's atoms absorb or emit light only at specific wavelengths, producing a set of spectral lines that act as fingerprints. When sunlight is spread by a prism or grating, dark absorption lines appear where atoms in the Sun's outer atmosphere swallowed particular wavelengths. Reading the lines' positions and strengths reveals the elements and their abundances. During the 1868 eclipse, scientists spotted helium this way — it was found in the sky before it was found on Earth.
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。
梁灿彬 等,《光学》,高等教育出版社
Liang Canbin et al., Optics, Higher Education Press
#光谱分析 #吸收线 #元素丰度
物理学家为什么一直在寻找「磁单极子」？它存在吗？
Why do physicists still search for magnetic monopoles, and do they exist?
自然界里磁极总是南北成对出现，没有单独存在的「磁荷」，这与电荷不对称。狄拉克1931年指出，若磁单极子存在，就能自然解释电荷为何都是基本电荷的整数倍（电荷量子化）。尽管粒子数据组（PDG）迄今未确认其存在，大型强子对撞机与宇宙线实验仍在搜寻，因为它关乎规范对称与早期宇宙。
Magnets always come with north and south poles together—no isolated 'magnetic charge'—asymmetrically unlike electric charge. Dirac showed in 1931 that if a monopole existed, it would naturally explain why all charges are integer multiples of the elementary charge (charge quantization). The Particle Data Group has found no confirmed monopole, yet the LHC and cosmic-ray experiments keep searching because it bears on gauge symmetry and the early universe.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
粒子数据组（PDG）《粒子物理学评论》「磁单极子」检索章节；P. A. M. 狄拉克 1931 年论文
Particle Data Group (PDG), 'Review of Particle Physics', Monopole Search section; P. A. M. Dirac (1931)
独立核验依据 · Independent verification: 核验依据 1 ARCHIVE 标识 Review_of_Particle_Physics：Review of Particle
#磁单极子 #狄拉克量子化 #规范对称
发电机靠什么原理把转动变成电？
What principle lets a generator turn spinning motion into electricity?
法拉第电磁感应定律说，穿过线圈的磁通量变化时会产生感应电动势。发电机让线圈在磁场中转动，磁通量不断变化，于是源源不断产生电流。
Faraday's law says a changing magnetic flux through a coil induces a voltage. A generator spins a coil in a magnetic field so the flux keeps changing, producing a continuous 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
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电磁感应 #法拉第定律 #发电机
闪电为什么是弯弯曲曲、分叉的锯齿状，而不是一条直线？
Why is lightning jagged and forked rather than a straight line?
闪电始于云层中的「阶梯先导」：电荷沿最易被击穿的空气通道一段段向下试探，每段约几十米，方向被局部电场和随机的离子不均匀性决定，于是呈锯齿状。当某条通道接近地面触发上行连接，主放电沿这条既成路径返回，就形成我们看到的闪电线，并常在半途分出叉枝。
Lightning begins with a 'stepped leader': charge probes downward in jagged segments of tens of meters, each step bent by local fields and random irregularities in ionized air. When one branch nears the ground and connects, the main discharge races back up that established path, producing the visible bolt—with forks where side branches formed.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#闪电 #阶梯先导 #放电通道
从无线电波到伽马射线都是电磁波，它们之间到底有什么区别？
Radio waves and gamma rays are both electromagnetic — so what really distinguishes them?
它们的本质相同，唯一区别在于频率和波长。频率越高，每个光子携带的能量越大，穿透力越强：无线电波用于广播和通信，微波用来加热食物，红外线用于夜视，可见光让我们看见世界，X射线能穿透软组织拍摄医学影像，伽马射线能量最高，可用于放疗。整个电磁波谱跨越了几十个数量级的频率范围。
They are the same kind of wave, differing only in frequency and wavelength. Higher frequency means more energy per photon and greater penetrating power: radio for broadcasting and communication, microwaves for cooking, infrared for night vision, visible light for sight, X-rays for medical imaging through soft tissue, and gamma rays, the most energetic, for radiotherapy. The full spectrum spans dozens of orders of magnitude in frequency.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电磁波谱 #频率 #光子能量
交流电和直流电有什么区别？
What is the difference between AC and DC?
直流电（DC）电流方向不变，如电池；交流电（AC）电流方向和大小周期性变化，如家用插座。交流电便于用变压器升压远距离输电。
Direct current (DC) flows one way, like from a battery. Alternating current (AC) reverses direction periodically, as in wall outlets, and is easy to step up for long-distance transmission.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Griffiths，《电动力学导论》（第4版）
Griffiths, 'Introduction to Electrodynamics' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-108-35938-2 (4th ed., Cambridge Univ. Press)
#交流电 #直流电 #输电
法拉第电磁感应告诉我们什么？
What does Faraday's law of electromagnetic induction tell us?
它说穿过一个回路的磁通量发生变化时，回路中就会产生感应电动势，其大小等于磁通变化率（楞次定律决定方向，总是阻碍变化）。发电厂让线圈在磁场中转动、改变磁通，正是靠这条原理发电。法拉第于1831年发现，是电动机与发电机的理论基础。
It states that when magnetic flux through a loop changes, an electromotive force is induced, equal in magnitude to the rate of flux change (Lenz's law gives the direction, opposing the change). Power plants spin coils in magnetic fields to vary flux and generate electricity by this law. Faraday discovered it in 1831, founding motors and generators.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
M. 法拉第 1831 年电磁感应实验记录；J. D. 杰克逊《经典电动力学》第5章
M. Faraday's 1831 induction experiments; J. D. Jackson, 'Classical Electrodynamics', Ch. 5
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2743722W：Classical electrodynami
#电磁感应 #法拉第定律 #磁通量
楞次定律说的“阻碍变化”到底指什么？
What does Lenz's law mean by opposing the change?
感应电流的方向总是使其磁场去抵抗引起它的磁通量变化，这正是能量守恒的要求。比如磁铁插入线圈时，线圈感应出的磁极会排斥磁铁，让你更费力。
The induced current flows so its own magnetic field resists the change in flux that caused it, as required by energy conservation. Pushing a magnet into a coil, the coil's poles repel it, costing you extra effort.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》
The Feynman Lectures on Physics
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#楞次定律 #感应电流 #能量守恒
手机和电动牙刷的无线充电靠的是什么物理原理？
What physical principle powers wireless charging in phones and toothbrushes?
它基于电磁感应（法拉第定律）：充电板里的线圈通交流电产生交变磁场，设备里的接收线圈「感」到变化磁通，便感应出电流给电池充电。把两个线圈靠近、对准，能量就通过磁场隔空传递，无需金属触点。国际标准如 IEC 61980 规定了电动汽车无线充电的线圈与频率。
It relies on electromagnetic induction (Faraday's law): an AC current in the pad's coil makes an alternating magnetic field, and the receiving coil in the device picks up the changing flux and induces a current to charge the battery. Aligning the coils transfers energy through the magnetic field without metal contacts. Standards like IEC 61980 specify coil and frequency for wireless EV charging.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
国际电工委员会（IEC）标准 IEC 61980（电动汽车无线供电系统）
International Electrotechnical Commission (IEC) standard IEC 61980 (wireless power transfer for EVs)
#无线充电 #电磁感应 #谐振耦合
变压器是怎么把电压升高或降低的？
How does a transformer step voltage up or down?
变压器由绕在同一个铁芯上的两组线圈构成。交变电流通过原线圈时产生交变的磁场，铁芯把这个磁通传递到副线圈，副线圈中就感应出电压。两个线圈的电压之比等于匝数之比：匝数多的一侧电压高而电流小。由于变压器只能作用于变化的磁场，直流电无法通过它升压，这也是电网坚持采用交流电的原因之一。
A transformer has two coils wound on a shared iron core. Alternating current in the primary coil creates an oscillating magnetic field, the core channels the flux to the secondary coil, and a voltage is induced there. The voltage ratio equals the turns ratio: the side with more turns gets higher voltage and lower current. Because transformers need a changing field, they cannot handle DC, which is one reason power grids use alternating current.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（电磁感应）
The Feynman Lectures on Physics, Vol. 2 (electromagnetic induction)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#变压器 #匝数比 #交流电
为什么说光其实就是一种电磁波？
Why is light said to be nothing but an electromagnetic wave?
麦克斯韦从自己的方程组推出：变化的电场会激发磁场，变化的磁场又会激发电场，两者交替产生并以波的形式在空间中传播，而且这种波的速度恰好等于当时实测的光速。他由此断定光就是电磁波。电磁波谱从无线电波、微波、红外一路延伸到可见光、紫外、X射线和伽马射线，可见光只是其中很窄的一段。
From his equations, Maxwell showed that a changing electric field generates a magnetic one and vice versa, and the two regenerate each other, traveling as waves through space at a speed that matched the measured speed of light exactly. He concluded that light is an electromagnetic wave. The spectrum runs from radio, microwave and infrared through visible light to ultraviolet, X-rays and gamma rays, with visible light only a narrow slice.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（电磁波）
The Feynman Lectures on Physics, Vol. 2 (electromagnetic waves)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#电磁波 #麦克斯韦 #光速
为什么电炉丝会发热，而连接它的铜导线却不怎么热？
Why does a heating coil get hot while the copper wires feeding it stay cool?
导体发热功率 P=I²R，与电阻成正比。炉丝用高电阻合金做成，电阻大，同样电流下发热多；铜导线电阻很小，发热就少。
The heat from a conductor is P=I²R, proportional to its resistance. The coil is made of a high-resistance alloy, so at the same current it heats far more than the low-resistance copper wire.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#焦耳热 #电阻 #电流
磁铁靠近线圈时，为什么线圈会"反抗"磁铁的运动？
Why does a coil "resist" the motion of a magnet approaching it?
这是楞次定律的体现：感应电流的方向总是让自己产生的磁场去阻碍引起它的磁通变化。磁铁靠近时，线圈产生一个排斥磁铁的磁场；磁铁远离时，线圈又产生一个吸引它的磁场。所以把强磁铁推进铜管时能感到明显的阻力。正是这股"别扭"的力量，让电磁感应成为发电机和电磁制动的根基。
Lenz's law: induced current always flows so that its own magnetic field opposes the flux change that created it. A magnet approaching a coil induces a repelling field; one moving away induces an attracting one, which is why a strong magnet pushed through a copper tube feels real drag. This stubbornness is the very effect that makes induction drive generators and electromagnetic brakes.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（楞次定律）
The Feynman Lectures on Physics, Vol. 2 (Lenz's law)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#楞次定律 #感应电流 #阻碍
微波炉是怎么把食物加热的？为什么盘子却不烫？
How does a microwave oven cook food, and why does the plate stay cool?
微波炉发出频率约2.45GHz的微波，使水分子这类带正负电荷的极性分子随电场高频转动、彼此碰撞摩擦生热。食物富含水分，所以热得快；普通陶瓷碟子不含极性分子，微波穿过而不被吸收，所以它本身不热。水分极少的物体（如干木片）在微波里几乎加热不了。
A microwave oven radiates about 2.45 GHz microwaves that make polar molecules like water tumble and collide, generating heat. Food is packed with water, so it heats quickly; an ordinary ceramic plate has no polar molecules, so microwaves pass through and it barely warms itself. Objects with almost no water — dry wood, for instance — hardly heat in a microwave at all.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#微波 #极性分子 #介电加热
为什么远距离输电要用几十万伏的高压？
Why is electricity transmitted over long distances at hundreds of thousands of volts?
输电线的电阻会把电能变成热，损耗的功率与电流的平方成正比。用变压器把电压升到几十万伏之后，输送同样功率所需的电流大大减小，线路损耗就按平方关系急剧下降。电到达城市后，再通过变压器逐级降回家庭使用的220伏。提高电压、压低电流，正是电网省电的核心手段。
Transmission lines turn electricity into heat, wasting power proportional to the square of the current. Stepping the voltage up to hundreds of kilovolts lets the same power flow with far less current, slashing resistive losses quadratically. Near cities, transformers step it back down to the 220 volts homes use. Boosting voltage to shrink current is the central trick of efficient power grids.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#高压输电 #焦耳损耗 #变压器
为什么微波炉里不能放金属餐具？
Why must you never put metal utensils in a microwave oven?
金属里的自由电子会被微波电场驱动，在表面形成强感应电流，而薄而尖的金属（如铝箔、镶金边的盘子）容易在边缘尖端积聚电荷、放电打火花，可能损坏微波源甚至引发危险。厚实的金属碗还会把微波反射回去，导致食物加热不均。所以微波炉要用无金属的容器。
Free electrons in metal are driven by the microwave's electric field into strong surface currents, and thin or pointed metal — foil, gold-trimmed plates — concentrates charge at edges where it can arc and spark, damaging the magnetron or creating a hazard. Thick metal bowls also reflect microwaves, leaving food unevenly heated. That's why microwave-safe dishes contain no metal.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#感应电流 #放电 #微波安全
发电机是怎么把机械能变成电能的？
How does a generator convert mechanical energy into electricity?
根据法拉第电磁感应定律，穿过线圈的磁通量一旦变化，线圈中就会产生感应电动势。发电机让线圈在磁场中持续转动，或者让磁铁在线圈内旋转，磁通量随之周期性变化，于是输出不断换向的交流电。发电站用水轮机、汽轮机或风力机带动转子旋转，机械能就这样源源不断地转化为电能。
Faraday's law of induction says a changing magnetic flux through a coil induces an electromotive force. A generator spins the coil inside a magnetic field, or spins the magnet within the coil, so the flux oscillates and alternating current flows. Turbines driven by water, steam or wind turn the rotor, continuously converting mechanical energy into electricity.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电磁感应 #发电机 #法拉第定律
手机和Wi-Fi是怎么把信息塞进空气里传出去的？
How do phones and Wi-Fi pack information into the air and send it?
它们用无线电波——电磁波的一种——来传信息。发送端先把文字、图片变成二进制的0和1，再用这些数据去调制高频无线电波，天线把载有数据的电波发射出去；接收端的天线收到后解调，还原出原始数据，变成你看到的画面和文字。电磁波以光速传播，所以信息几乎瞬间到达。
They use radio waves, a form of electromagnetic radiation. The transmitter first turns text and images into binary 0s and 1s, then uses those bits to modulate a high-frequency radio carrier; the antenna radiates the data-laden waves, and the receiver's antenna picks them up and demodulates them back into the original content. Since EM waves travel at light speed, the information arrives almost instantly.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#无线电波 #调制与解调 #电磁波
电容器有什么作用？
What does a capacitor do?
电容器是由两层导电板和中间绝缘体组成的元件，能储存电荷和电能。它在电路中可以滤波、定时或瞬间释放大电流。
A capacitor consists of two conducting plates separated by an insulator and stores electric charge and energy. In circuits it can filter signals, set timing, or release bursts of current.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电容器 #储能 #电路
电磁波是如何传播的？
How do electromagnetic waves propagate?
变化的电场产生磁场，变化的磁场又产生电场，二者相互激发并向前传播，形成横波。它不需要介质，可在真空中以光速传播。电场与磁场方向互相垂直，且都垂直于传播方向。
A changing electric field creates a magnetic field, which in turn creates a changing electric field, and the two mutually excite and propagate forward as a transverse wave. It needs no medium and travels through vacuum at light speed. The electric and magnetic fields are perpendicular to each other and to the direction of travel.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电磁波 #相互激发 #横波
两根平行的通电导线为什么会同向相吸、反向相斥，安培力本质上来自什么？
Why do two parallel current-carrying wires attract when currents are parallel and repel when antiparallel, and what is the Ampère force really from?
一根导线的电流在周围产生环形磁场，另一根导线中的载流子在该磁场中受洛伦兹力，宏观上就是 F = IL×B。用右手定则可验证：电流同向时第二根导线受力指向第一根，故相吸；电流反向时受力朝外，故相斥。相距 1 米的两根长直导线各通 1 安培时，每米作用力约 2×10⁻⁷ N，历史上正是用这条关系定义安培的。
The current in one wire sets up a circular magnetic field, and the moving carriers in the other wire feel a Lorentz force in it, which macroscopically is F = IL×B. The right-hand rule shows that for parallel currents this force points toward the first wire (attraction), while for antiparallel currents it points outward (repulsion). Two long straight wires 1 m apart each carrying 1 A feel about 2×10⁻⁷ N per metre—the relation once used to define the ampere.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
D. J. Griffiths,《Introduction to Electrodynamics》(第4版),第5章(静磁场:洛伦兹力与安培定律)
D. J. Griffiths, 'Introduction to Electrodynamics' (4th ed.), Ch.5 (Magnetostatics: Lorentz force and Ampère's law)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-108-35938-2 (4th ed., Cambridge Univ. Press)
#安培力 #载流导线 #磁场相互作用
欧姆定律是什么？
What is Ohm's law?
欧姆定律指出，在温度不变时导体中的电流与电压成正比、与电阻成反比，公式为 I=V/R。它帮助我们计算电路中的电流大小。
Ohm's law states that, at constant temperature, current through a conductor is proportional to voltage and inversely proportional to resistance, I=V/R. It lets us calculate current in circuits.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#欧姆定律 #电压 #电阻
什么是电流？
What is electric current?
电流是电荷的定向移动，单位为安培。电池或发电机提供电势差，推动电子在导线中流动，从而点亮灯泡或驱动电器。
Electric current is the directed flow of electric charge, measured in amperes. A battery or generator provides a voltage difference that drives electrons through a wire, powering lights and devices.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电流 #电荷 #安培
法拉第电磁感应定律如何应用？
How is Faraday's law of induction applied?
法拉第定律指出，穿过回路的磁通量变化时会在回路中产生感应电动势，大小等于变化率。发电机、变压器都依据这一原理把机械能或电压进行转换。它是现代电力技术的基石。
Faraday's law says a changing magnetic flux through a loop induces an electromotive force proportional to its rate of change. Generators and transformers rely on this to convert mechanical energy or voltages. It is the cornerstone of modern electrical technology.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#法拉第定律 #感应电动势 #磁通
什么是电场？
What is an electric field?
电场是电荷周围存在的一种特殊物质，能对放入其中的其他电荷施加力的作用。电场强度用单位正电荷所受的力来定义。
An electric field is a physical field around a charge that exerts force on other charges placed within it. Its strength is defined by the force on a unit positive charge.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电场 #电荷 #力
为什么在电梯里手机常常收不到信号？
Why do phones often lose signal inside an elevator?
电梯是金属围成的箱子，金属外壳会感应出与外来电场相反的电荷，把内部空间里的电磁场抵消掉，形成法拉第笼，无线电波进不来，手机自然没有信号。反过来看，这个原理也在保护我们：避雷针让雷电流走金属外壳入地，医院手术室用屏蔽墙挡住外来电磁波。
An elevator is a metal box, and the metal responds to an incoming electric field by rearranging surface charges that cancel the field inside — a Faraday cage. Radio waves can't get in, so the phone finds no signal. The same idea protects us elsewhere: lightning rods route current through metal to the ground, and shielded operating rooms keep external electromagnetic waves out.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第二卷（静电屏蔽）
The Feynman Lectures on Physics, Vol. 2 (electrostatic shielding)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#法拉第笼 #电磁屏蔽 #感应电荷
为什么肥皂泡和光盘表面会泛出五彩的颜色？
Why do soap bubbles and the surface of a CD shimmer with color?
光盘表面刻着间距与光波长相当的密集凹槽，反射光在沟槽间发生干涉——不同波长的光在某些角度加强、在某些角度抵消，于是不同角度显出不同颜色，这叫衍射光栅效应。肥皂泡则是前后两个膜面反射的光发生薄膜干涉产生颜色。两者的颜色都不是颜料染的，而是光波叠加的结果。
A CD's surface carries fine grooves spaced about as far apart as light's wavelength; light reflecting off them interferes, strengthening some wavelengths and cancelling others at each viewing angle, so different angles show different colors — diffraction-grating color. A soap bubble colors light through thin-film interference between its two reflecting surfaces. Neither color comes from pigment; both are pure wave superpositions.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第一卷（干涉与衍射）
The Feynman Lectures on Physics, Vol. 1 (interference and diffraction)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#衍射 #薄膜干涉 #光栅
电容是做什么的，为什么闪电能劈中高塔？
What does a capacitor do, and why can lightning strike a tall tower?
电容能储存电荷，两板间电压越高存的电越多。云层与地面构成巨大“电容”，电荷积累到击穿空气时便放电成闪电，高塔尖端更易集中电场而被击中。
A capacitor stores charge, with more voltage meaning more stored. Cloud and ground form a giant capacitor; when charge builds until air breaks down, lightning discharges, and a tall tower's tip concentrates the field so it is struck first.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电容 #闪电 #电场
避雷针是怎么保护房子的？
How does a lightning rod protect a building?
避雷针是高处尖端的金属导体，能把雷电引到自己身上，再通过导线安全地导入地下，避免击中房屋。
A lightning rod is a pointed metal conductor on high points that attracts the strike and safely channels the current to ground, sparing the building.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Franklin，《电学实验与观察》（1751）
Franklin, 'Experiments and Observations on Electricity' (1751)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.5479/sil.211644.39088000092304：Experiment
#避雷针 #雷电 #接地
电容器为什么能储存能量？
Why can a capacitor store energy?
充电时电荷被分离到两板，建立电场，外力克服板间吸引力做功，能量以电场形式储存在极板之间。储能大小为 ½CV²，其中 C 是电容、V 是电压。
Charging separates charge onto the two plates, building an electric field; work done against the attractive force is stored as field energy between the plates. The stored energy is ½CV², with C the capacitance and V the voltage.
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。
Purcell 与 Morin《电磁学》
Purcell & Morin, Electricity and Magnetism
#电容器 #电场能 #电容
电动机靠什么力把电变成转动？
What force turns electricity into rotation in a motor?
通电导线在磁场中受安培力（F=IL×B），方向由左手定则决定。让电流方向随转子位置不断切换，导线就持续受到推动而旋转。
A current-carrying wire in a magnetic field feels the Ampère force (F=I L×B), set by the left-hand rule. Switching the current as the rotor turns keeps pushing it around, producing rotation.
难度 进阶 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
David J. Griffiths 著《Introduction to Electrodynamics》（电动力学导论）
David J. Griffiths, Introduction to Electrodynamics
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-108-35938-2 (4th ed., Cambridge Univ. Press)
#安培力 #电动机 #磁场
什么是磁场？
What is a magnetic field?
磁场是磁体或电流周围存在的特殊场，能对运动电荷和磁体施加磁力。我们可以用磁感线来形象地表示磁场的方向和强弱。
A magnetic field is a field around magnets or electric currents that exerts magnetic force on moving charges and other magnets. Magnetic field lines help visualize its direction and strength.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
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梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#磁场 #磁力 #磁感线
为什么X光能照出骨头，却照不清肌肉？
Why do X-rays show bones clearly but barely show muscles?
X光是能量很高的电磁波，穿透力强。骨骼富含钙，钙的原子序数高，吸收X光的能力强，在片子上显白色；肌肉等软组织主要由碳、氢、氧等轻元素构成，X光大多直接穿过，在片子上显暗色。X光照片其实就是不同组织穿透率差异的成像记录。同样的原理也让X光用于安检和晶体结构分析。
X-rays are extremely energetic electromagnetic waves that penetrate matter. Bone is rich in calcium, a high-atomic-number element, so it absorbs X-rays strongly and appears white on the image; muscle and other soft tissue are mostly light elements like carbon, hydrogen, and oxygen, so X-rays sail through and the tissue looks dark. An X-ray picture is simply a record of how differently tissues let the rays through, and the same principle drives airport scanners and crystal-structure analysis.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#X射线 #穿透 #钙
为什么磁铁总有两极，不能只留下一极？
Why do magnets always have two poles and you can't isolate just one?
磁体里的小磁针成对排列，南北极总是同时出现。即使把磁铁掰成两半，每半又各自长出新的南北极。磁单极子至今未在实验中被确证。
Inside a magnet the tiny magnetic arrows come in pairs, so north and south always appear together. Break a magnet in half and each piece grows its own new poles. Magnetic monopoles have not been confirmed in experiment.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
David J. Griffiths 著《Introduction to Electrodynamics》（电动力学导论）
David J. Griffiths, Introduction to Electrodynamics
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-108-35938-2 (4th ed., Cambridge Univ. Press)
#磁极 #磁场 #磁单极
闪电是怎么形成的？
How does lightning form?
雷雨云中冰晶碰撞使云层上下积累了正负电荷，当电势差足够大时空气被击穿，形成强烈的放电，这就是闪电。它瞬间温度极高，还伴随雷声。
Inside a storm cloud, colliding ice crystals separate positive and negative charges, and when the voltage grows large enough the air breaks down in a powerful discharge: lightning. It reaches very high temperatures and is followed by thunder.
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
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#闪电 #放电 #电荷
为什么湿手碰电器更危险？
Why is it more dangerous to touch electricity with wet hands?
水（尤其含杂质）能导电，湿手让电流更容易穿过身体，增加触电危险。所以千万别用湿手碰插座。
Water (especially impure) conducts electricity, so wet hands let current flow through your body more easily, raising shock risk. Never touch outlets with wet hands.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
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Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#导电 #触电 #安全
变压器为什么能把交流电压升高或降低，却对直流电几乎无能为力？
Why can a transformer raise or lower AC voltage but hardly do anything with DC?
变压器靠变化的磁场在副线圈中感应出电压，交流电不断改变方向，才能持续产生变化的磁通。直流电的大小和方向基本不变，磁通恒定，副线圈里就不会产生感应电压。所以变压器是交流设备的专属。
A transformer induces voltage in the secondary coil through a changing magnetic flux, which only an alternating current can provide. With direct current the flux is steady, so no voltage is induced in the secondary. Transformers therefore work only with AC.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
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D. J. Griffiths,《Introduction to Electrodynamics》(第4版),第7章(法拉第定律)
D. J. Griffiths, 'Introduction to Electrodynamics' (4th ed.), Ch.7 (Faraday's law)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-108-35938-2 (4th ed., Cambridge Univ. Press)
#电磁感应 #变压器 #交流电
什么是电荷？
What is electric charge?
电荷是物质带有的一种基本属性，分为正电荷和负电荷两种。同种电荷互相排斥，异种电荷互相吸引，这是电磁现象的根源。
Electric charge is a basic property of matter, coming in positive and negative kinds. Like charges repel and opposite charges attract, and this underlies all electromagnetic phenomena.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电荷 #正负 #电磁
电池是怎么供电的？
How does a battery supply power?
电池内部通过化学反应把化学能转化为电能，在正负极之间建立电压。连接电路后，电子从负极流向正极，形成持续的电流。
Inside a battery, chemical reactions convert chemical energy into electric energy, creating a voltage between its terminals. Once connected, electrons flow from the negative to the positive terminal, sustaining a current.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电池 #化学能 #电压
用气球在头发上蹭几下再靠近墙壁，为什么气球会贴在墙上不掉下来？
After rubbing a balloon on your hair and bringing it near a wall, why does the balloon stick instead of falling?
摩擦让气球表面带上静电荷，带电极化的气球会吸引墙面上被感应出的异号电荷，产生微弱但足够克服重力的静电力。干燥环境下电荷不易流失，所以能贴住片刻。这是库仑力在日常生活中最直接的表演。
Friction deposits static charge on the balloon's surface; the charged balloon polarizes the wall and attracts the opposite charges induced there, producing an electrostatic force strong enough to beat gravity for a while. In dry air the charge lingers, so the balloon stays put briefly. It is Coulomb's force on everyday display.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
R. P. Feynman, R. B. Leighton & M. Sands,《The Feynman Lectures on Physics》Vol. II(1964),第4章(静电学)
R. P. Feynman, R. B. Leighton & M. Sands, 'The Feynman Lectures on Physics' Vol. II (1964), Ch.4 (Electrostatics)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#静电 #摩擦起电 #库仑力
什么是电磁场？
What is an electromagnetic field?
电磁场是充满空间、传递电力和磁力并携带动量和能量的物理场。电荷和电流是场的源，场的变化又会以光速向外传播。它没有传统意义上的实体，却是真实可测量、可操控的。
The electromagnetic field is a physical field filling space that transmits electric and magnetic forces and carries momentum and energy. Charges and currents are its sources, and changes in the field propagate outward at light speed. It has no conventional substance yet is real, measurable, and controllable.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电磁场 #场 #电荷
指南针的指针为什么总是指向南北方向，而不是随便乱指？
Why does a compass needle always point north–south instead of pointing in any random direction?
地球本身像一个巨大的磁体，周围存在地磁场。指南针是小磁针，在地磁场的作用下会转向与磁场线一致的方向，于是大致指向地理南北。磁针的北端被地磁南极（靠近地理北极）吸引。
Earth behaves like a giant magnet with its own magnetic field. A compass is a small magnetic needle that aligns with the local magnetic field lines, so it points roughly toward geographic north and south. The needle's north-seeking end is pulled toward Earth's magnetic south pole, near the geographic North Pole.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
D. J. Griffiths,《Introduction to Electrodynamics》(第4版),第5章(静磁场)
D. J. Griffiths, 'Introduction to Electrodynamics' (4th ed.), Ch.5 (Magnetostatics)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-108-35938-2 (4th ed., Cambridge Univ. Press)
#地磁场 #磁针 #指南针
为什么冬天脱毛衣会有噼啪声和小火花？
Why do clothes crackle and spark when you take them off in winter?
摩擦让衣物之间转移了电荷，积累起静电。干燥空气不易导电，电荷越积越多，最后放电产生可见的小火花和噼啪声。
Rubbing shifts electric charge between fabrics, building up static. Dry air conducts poorly, so the charge grows until it suddenly discharges as a tiny visible spark and crackle.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#静电 #放电 #摩擦起电
电场和磁场是什么关系？
What is the relationship between electric and magnetic fields?
电场和磁场是统一的电磁场在不同参考系下的不同表现。运动电荷产生磁场，变化的磁场又产生电场。在相对论看来，二者本质上是同一种物理量在不同观察者眼中的投影。
Electric and magnetic fields are aspects of one unified electromagnetic field seen differently in different reference frames. A moving charge creates a magnetic field, and a changing magnetic field creates an electric field. In relativity they are essentially the same physical quantity viewed by different observers.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#电场 #磁场 #电磁统一
磁铁为什么会吸铁？
Why do magnets attract iron?
磁铁周围存在磁场，铁等铁磁性材料进入磁场后会被磁化而产生吸引力。同名磁极相斥，异名磁极相吸。
A magnet produces a magnetic field around it; iron and similar ferromagnetic materials become magnetized in that field and are attracted. Like poles repel and opposite poles attract.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
梁灿彬 等,《电磁学》,高等教育出版社,2004
Liang Canbin et al., Electromagnetism, Higher Education Press, 2004
#磁铁 #磁场 #磁性
指南针的指针为什么总指向北方？
Why does a compass needle point north?
地球本身像一个巨大的磁偶极，产生从南地理极附近发出的磁场。指南针的小磁针在地磁场力矩作用下，总是让磁北极一端转向地磁南极（即地理北方附近）。
The Earth behaves like a giant magnetic dipole, generating a field that emerges near the geographic South Pole. The compass needle experiences a torque from this field and aligns its north-seeking end toward the magnetic south pole, near geographic north.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03 · 2 条独立证据
来源 · Source
Jackson《经典电动力学》；NASA 地球磁场观测数据
Jackson, Classical Electrodynamics; NASA Earth magnetic field materials
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787040144321（豆瓣书目条目: 经典电动力学）；本条出处含多部著作，此标识只担保上面点名的 · 核验依据 2 OPENLIBRARY 标识 /works/OL2743722W：Classical electrodynami
#地磁场 #指南针 #磁偶极
磁铁能吸住哪些东西?哪些东西它吸不住?
Which things can a magnet pick up, and which can it not?
磁铁有一种特别的本领,能把铁做的东西拉近自己,比如铁钉、曲别针和小铁勺,这种本领叫磁性。木头积木、塑料尺和玻璃杯里没有铁,磁铁就吸不住它们。有些硬币悄悄含着铁,放在磁铁上会乖乖贴住,你可以动手试一试。
A magnet has a special power called magnetism: it pulls things made of iron toward itself, like iron nails, paper clips, and small iron spoons. Wooden blocks, plastic rulers, and glass cups hold no iron, so the magnet cannot grab them. Some coins secretly contain iron and will stick tightly on a magnet; try it yourself!
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《十万个为什么》第六版物理分册,少年儿童出版社,2013
Ten Thousand Whys: Physics volume, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#磁铁 #磁性 #铁制品