太阳能板在大太阳下发烫，为什么反而效率下降？
Why does a hot solar panel become less efficient in bright sun?
硅电池的输出功率主要取决于开路电压，而温度升高会使少数载流子浓度上升、pn结的势垒降低，开路电压随之下降，通常每升高1℃损失约0.3%到0.45%的功率。所以组件要留通风间隙散热。
A silicon cell's power hinges on its open-circuit voltage, and heating raises minority-carrier concentration and lowers the junction barrier, so that voltage drops — typically 0.3–0.45 % of power per degree. This is why panels are mounted with an air gap for cooling.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Shockley 与 Queisser，《p-n 结太阳能电池效率的详细平衡极限》，Journal of Applied Physics 32 (1961)
Shockley & Queisser, 'Detailed Balance Limit of Efficiency of p-n Junction Solar Cells', Journal of Applied Physics 32 (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
#光伏 #温度系数 #pn结
原子钟凭什么能几千万年不差一秒？
How can an atomic clock stay accurate to a second over tens of millions of years?
它不用宏观零件当节拍器，而是利用铯或锶原子两个能级之间的跃迁频率。这个频率由量子力学和自然常数决定，同种原子处处相同，也几乎不受温度和机械磨损影响；仪器只需把微波锁定在这个跃迁上。
Instead of a mechanical pendulum it uses the transition frequency between two energy levels of caesium or strontium atoms. That frequency is fixed by quantum mechanics and is identical for every such atom, immune to wear, so the electronics only has to lock a microwave signal onto it.
难度 专业 · 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）
#原子钟 #能级跃迁 #时间标准
锂电池充放电的时候，里面到底在搬运什么？
What is actually shuttling inside a lithium battery?
充电时锂离子从正极材料脱出，穿过电解液嵌入石墨负极，电子则被迫走外电路；放电时反向进行。所以它被称为“摇椅电池”，能量存在锂离子所处位置的化学势差里。
On charge, lithium ions leave the cathode, cross the electrolyte and slot into the graphite anode while electrons travel the external circuit; discharge reverses it. Hence the nickname rocking-chair battery, with energy stored in the ions' difference in chemical potential.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Whittingham，《可充电电池中的电能储存》，Science 192 (1976)
Whittingham, 'Electrical Energy Storage and Intercalation Chemistry', Science 192 (1976)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1126/science.192.4244.1126：Electrical Ene
#锂电池 #离子输运 #电化学
体重秤里的应变片是怎么把重量变成数字的？
How does the strain gauge in a bathroom scale turn weight into a number?
应变片是一种受拉伸或压缩时电阻会微小变化的电阻。体重秤的传感器（称重梁）上贴着四个应变片，组成惠斯通电桥；重量使梁弯曲、电桥失衡，产生与受力成正比的微弱电压。电路把电压放大并转换成数字，就显示出体重读数。
A strain gauge is a resistor whose resistance changes slightly when stretched or compressed. Four such gauges on the scale's load cell form a Wheatstone bridge; the weight bends the cell, unbalancing the bridge and producing a small voltage proportional to the force. That voltage is amplified and converted to a digital number showing your weight.
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。
Doeblin 与 Manus，《测量系统：应用与设计》（第5版）
Doeblin & Manus, 'Measurement Systems: Application and Design' (5th ed.)
#应变片 #惠斯通电桥 #传感器
血压计为什么要一边放气一边听声音？
Why does a blood-pressure cuff need someone listening while it deflates?
血压计先充气压迫手臂使血流停止，再缓慢放气，同时用听诊器听肱动脉处的柯氏音。当压力降到收缩压以下，血液在受压变窄的血管里湍流冲过，发出“嗒嗒”声；降到舒张压以下后血流恢复平稳，声音消失。听到声音起始与消失所对应的压力，就是收缩压和舒张压。
The cuff is inflated to stop blood flow in the arm, then slowly deflated while a stethoscope listens over the brachial artery for Korotkoff sounds. As pressure drops below systolic, blood spurts turbulently through the pinched artery and produces tapping sounds; once it falls below diastolic, flow becomes smooth and silent. The pressures at which sound begins and ends mark the systolic and diastolic readings.
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：作者 / 书名 / 版次 / 出版社 / 年份齐备，仅缺独立比对证据；已在可信度报告单列披露，不再重复核验。
Korotkoff，《研究血压方法的问题》（1905）
Korotkoff, 'On the Methods of Studying Blood Pressure' (1905)
#血压 #湍流 #柯氏音
天平和电子秤测的是同一个量吗？
Do a balance and a digital scale measure the same thing?
不完全一样。等臂天平比较两侧的重力矩，结果与当地重力加速度无关，测的是质量。电子秤测的是压在传感器上的力，再除以设定的重力加速度换算成质量，换到重力略有差异的地点就需要重新校准。
Not quite. A beam balance compares gravitational torques, so its reading is independent of local gravity and truly reflects mass. A digital scale senses force and divides by an assumed gravity value, so it must be recalibrated where gravity differs.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
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
#质量 #重力 #计量
机械表的擒纵机构和石英表的晶振，为什么后者准得多？
Why is a quartz watch far more accurate than a mechanical escapement?
机械表靠摆轮游丝每秒摆动几次，频率受温度、姿态、润滑和发条力矩影响。石英表让石英晶体以32768赫兹稳定振动，频率高、品质因数大、对环境不敏感，分频计数后误差可以小到每月几秒。
A balance wheel oscillates only a few times per second and is disturbed by temperature, position, oil and mainspring torque. A quartz crystal vibrates at 32768 Hz with a very high quality factor and little environmental drift, so dividing that count keeps error to seconds per month.
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：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。
Marrison，《石英晶体钟的演进》，Bell System Technical Journal 27 (1948)
Marrison, 'The Evolution of the Quartz Crystal Clock', Bell System Technical Journal 27 (1948)
#钟表 #振荡器 #品质因数
气体探测器和闪烁体探测器在记录带电粒子能量沉积时,各自的信号形成机制有什么本质区别?
What is the fundamental difference in signal formation between gas detectors and scintillation detectors when recording charged-particle energy deposition?
气体探测器依赖电离产生的离子对在外加电场下漂移,信号来自感应电荷的移动,成形时间通常为微秒量级,增益由雪崩倍增过程提供。闪烁体探测器则把能量沉积转化为可见光子,光子经光电倍增管或 SiPM 转换成电子信号,响应时间为纳秒量级。前者直接给出电荷量信息、能量分辨率好但计数率受限;后者时间分辨优异,适合高计数率和快触发。
Gas detectors rely on ion pairs drifting under an applied field, so the signal arises from induced-charge motion with microsecond-scale shaping times and gain supplied by avalanche multiplication. Scintillators convert deposited energy into visible photons that a PMT or SiPM converts into an electronic pulse, giving nanosecond response. The former yields direct charge information with good energy resolution but limited rate capability; the latter offers excellent timing for high-rate and fast-trigger applications.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Knoll《Radiation Detection and Measurement》第5章与第8章;Leo《Techniques for Nuclear and Particle Physics Experiments》第6章
Knoll, Radiation Detection and Measurement, chs. 5 & 8; Leo, Techniques for Nuclear and Particle Physics Experiments, ch. 6
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1007/978-3-642-96997-3：Techniques for Nuc
#电离室 #闪烁体
半导体辐射探测器相比气体探测器和闪烁体有哪些优势?高纯锗探测器为何需要低温工作?
What advantages do semiconductor radiation detectors offer over gas detectors and scintillators, and why must high-purity germanium detectors operate cryogenically?
半导体探测器中每产生一对电子-空穴约需3.6 eV电离能(硅),远低于气体探测器的约30 eV和闪烁体输出数千个可见光子才对应一次事件的情况,因此能量分辨率可提高一到两个数量级。高纯锗的禁带宽度仅0.67 eV,室温热激发足以产生严重的漏电流噪声淹没信号。所以探测器通常用液氮冷却到77 K附近运行,以压低暗电流并保持PN结耗尽区的收集效率。
In semiconductor detectors each electron-hole pair costs about 3.6 eV of ionization energy, far less than the roughly 30 eV per ion pair in gas detectors or the thousands of visible photons needed per event from scintillators, so energy resolution improves by one to two orders of magnitude. High-purity germanium has a bandgap of only 0.67 eV, allowing room-temperature thermal excitation to generate leakage-current noise that would swamp the signal. Detectors are therefore cooled with liquid nitrogen near 77 K to suppress dark current and preserve charge-collection efficiency in the depleted junction region.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
G. F. Knoll, Radiation Detection and Measurement, 4th ed., Wiley (2010), Ch. 12: Semiconductor detectors
G. F. Knoll, Radiation Detection and Measurement, 4th ed., Wiley (2010), Ch. 12: Semiconductor detectors
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL15616993W：Radiation detection an
#辐射探测器 #能量分辨率
为什么手机在很冷的室外掉电特别快？
Why does a phone lose charge so fast in the cold?
电池里的离子要在液体里游动才能供电，天冷时它们变得又慢又懒，电池的内阻变大，能拿出来的电就变少。回到暖和的地方，电量常常又“回来”一些。
The battery works by ions moving through a liquid, and cold makes them sluggish, so the battery's internal resistance rises and less energy can come out. Back in the warmth some of the charge often seems to return.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Linden 与 Reddy，《电池手册》（第4版）
Linden & Reddy, '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)
#电池 #温度 #内阻
水银体温计和电子体温计的原理有什么不同？
How do mercury and electronic thermometers differ inside?
水银温度计靠液体受热膨胀，用体积变化指示温度。电子温度计里是热敏电阻或热电偶，温度改变电阻或产生微小电压，芯片再把电信号换算成读数。
A mercury thermometer relies on liquid expanding with heat, reading temperature from volume. An electronic one uses a thermistor or thermocouple whose resistance or voltage shifts with temperature, and a chip converts that signal into a number.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
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
#温度计 #热膨胀 #热敏电阻
LED 灯泡为什么比白炽灯省那么多电？
Why is an LED bulb so much more efficient than an incandescent one?
白炽灯是把钨丝烧到两千多度靠热辐射发光，绝大部分能量落在看不见的红外区，可见光效率只有几个百分点。LED 让电子在半导体结中直接复合发出特定波长的光，几乎不必先把材料烧热。
An incandescent lamp glows by heating tungsten to over 2000 °C, and most of that radiation is invisible infrared, leaving only a few percent as visible light. An LED makes electrons recombine in a semiconductor junction to emit light directly, with no need to heat anything first.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Shockley 与 Queisser，《p-n 结太阳能电池效率的详细平衡极限》，Journal of Applied Physics 32 (1961)
Shockley & Queisser, 'Detailed Balance Limit of Efficiency of p-n Junction Solar Cells', Journal of Applied Physics 32 (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
#LED #发光效率 #热辐射