遥控器用红外线传信号，为什么对着墙也能偶尔控到电视？
Remotes use infrared, so why can they sometimes work even aimed at a wall?
红外光会被浅色墙面漫反射，部分反射光仍能进入电视接收窗；但红外是视线通信、会被遮挡，所以多数要大致对准。
IR reflects off light walls so some reaches the receiver, but it is line-of-sight and blocked by obstacles, so aiming helps.
难度 专业 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#遥控器 #红外 #反射
微波炉为什么用微波而不是火来加热食物？
Why does a microwave heat food with waves instead of fire?
微波约2.45GHz让食物里的水等极性分子高速往复翻转、摩擦生热，是从内部加热；金属腔体把波限制在里面，转盘让受热更匀。
At about 2.45GHz microwaves make polar molecules like water jiggle and heat from inside; the metal cavity confines the waves and the turntable evens heating.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#微波炉 #极性分子 #加热
净水器的RO反渗透膜为什么能把盐和病毒挡住，却让水过去？
How can an RO membrane block salt and viruses but let water through?
RO膜孔径约0.0001微米，介于水分子团和离子之间；靠高压把水压过膜，溶解的盐离子和多数污染物被截留，几乎是物理筛分加电荷排斥。
The RO pore is between a water cluster and an ion; high pressure pushes water through while dissolved ions and most contaminants are rejected by size and charge.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
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Baker，《膜技术及应用》（第3版）
Baker, 'Membrane Technology and Applications' (3rd ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL21484808W：Membrane Technology an
#净水 #反渗透 #膜
超声波加湿器和往外冒白雾的那种，原理一样吗？
Are ultrasonic humidifiers the same as the misty kind?
不一样。超声波型用高频振动把水打成微米水雾；蒸发型靠风扇吹过湿网自然蒸发，不起白雾也不易把水垢吹出。
Ultrasonic ones vibrate water into a fine mist; evaporative ones blow air through a wet wick, with no white plume and less mineral spray.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Kinsler、Frey、Coppens & Sanders，《声学基础》（第4版）
Kinsler, Frey, Coppens & Sanders, 'Fundamentals of Acoustics' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780471847892 (2000)
#加湿器 #超声波 #蒸发
抽油烟机为什么能把油烟吸走而不是让它在屋里乱飘？
How does a range hood capture grease-laden smoke instead of letting it drift?
风机在集烟腔形成负压，把上升的油烟抽进滤网和风道排到室外；风速和罩口形状决定能罩住多大范围，太远就抓不住。
The fan makes the hood negative-pressure, drawing rising air through filters and out; airflow and hood shape decide the capture zone.
难度 专业 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Munson，《流体力学基础》（第8版）
Munson, 'Fundamentals of Fluid Mechanics' (8th ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL2677306W：Fundamentals of fluid m
#抽油烟机 #负压 #捕集
变频空调为什么比定频空调省电，它凭什么不用频繁开停？
Why does an inverter air conditioner use less energy than a fixed-speed one that keeps cycling?
定频压缩机只能全速运行或停机，靠反复开停维持温度，每次重启都要重新建立油膜与压差、承受启动电流冲击，停机期间制冷剂迁移还带来额外损失，室温也在设定值上下摆动。变频机通过改变供给压缩机的电源频率连续调节转速，长期在部分负荷下低速运行——此时换热面积相对过剩，蒸发温度升高、冷凝温度降低，压缩比减小，能效比反而高于满负荷。因此季节能效指标（如 APF、SEER）明显优于定频机，代价是电子器件更多，变频器本身也有几个百分点的损耗。
A fixed-speed compressor can only run flat out or stop, so it cycles to hold temperature, and every restart must re-establish oil films and pressure difference, endure inrush current and recover refrigerant migration losses while room temperature swings around the setpoint. An inverter varies the frequency fed to the compressor and hence its speed, letting it run slowly at part load where the heat exchangers are effectively oversized, evaporating temperature rises, condensing temperature falls, pressure ratio drops and the coefficient of performance actually exceeds the full-load value. Seasonal metrics such as APF or SEER therefore favour inverter units clearly, at the price of more electronics and a few percent of loss in the drive itself.
难度 进阶 · 适合 小学高段(9-12)
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。
ASHRAE Handbook—HVAC Systems and Equipment（2020），压缩机与制冷设备章
ASHRAE Handbook—HVAC Systems and Equipment (2020), compressors and refrigeration equipment chapters
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL38979624W：2004 ASHRAE Handbook--
#变频空调 #部分负荷能效 #压缩机调速
风冷『无霜』冰箱其实也会结霜，它是怎么把霜化掉又不让食物变热的？
Frost-free refrigerators do form frost — how do they melt it off without warming the food?
风冷冰箱把蒸发器藏在箱体后部的风道里，风机吹动箱内空气经过蒸发器降温除湿，水汽全部凝结在这块看不见的翅片上，所以食品间看不到霜。控制器按压缩机累计运行时间或化霜传感器判断结霜量，定期停止制冷并接通蒸发器上的电加热丝几分钟，融化的水沿排水槽流到压缩机上方的接水盘，靠压缩机余热蒸发掉。化霜期间压缩机与风机停转，箱体保温使内部只升温几度且时间很短，随后立即恢复制冷；代价是电加热与循环风机带来额外能耗，箱内空气偏干使不密封的食物更容易失水。
A frost-free unit hides its evaporator in an air duct behind the cabinet, and a fan draws cabinet air across those cold fins so all moisture condenses there instead of on food shelves. A controller decides from accumulated compressor run time or a defrost sensor when to pause cooling and switch on an electric heater at the evaporator for a few minutes; meltwater drains to a pan above the compressor and evaporates using its waste heat. During defrost the compressor and fan stop while the insulated cabinet limits warming to a few degrees for a short time before cooling resumes, the costs being extra energy for heater and circulating fan and drier air that desiccates unwrapped food.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Dossat 与 Horan，《Principles of Refrigeration》（第5版）
Dossat & Horan, 'Principles of Refrigeration' (5th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780130272706 (2002)
#风冷冰箱 #自动化霜 #蒸发器
手机快充功率那么高，为什么一般不会把电池充坏？
Fast chargers are very powerful, so why don't they wreck the battery?
充电芯片按先恒流后恒压的协议智能调节，并实时监测温度和电压；快充只是前期提高电流，接近满电时自动放缓以保护电池。
A controller follows a constant-current then constant-voltage profile and watches temperature and voltage, tapering off near full to protect the cell.
难度 进阶 · 适合 大众
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)
#手机 #快充 #电池管理
电饭煲怎么知道饭煮好了？
How does a rice cooker know the rice is done?
米水混合物沸腾时温度保持在约100℃；水收干后锅底温度迅速越过100℃上升，温控器据此跳到保温。
While boiling the pot stays near 100℃; once water is gone the temperature climbs, and a thermostat switches to keep-warm.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#电饭煲 #温控 #沸腾
电梯的钢缆万一断了，轿厢会直接掉下去吗？
If an elevator cable snaps, will the car just fall?
不会。电梯通常有数根并列钢缆、极少同时断；即便失速，限速器也会触发安全钳把轿厢死死夹在导轨上。
No. Several ropes run in parallel and rarely all fail; if speed runs away, a governor triggers safety gears that clamp the car to the rails.
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。
ASME A17.1，《电梯与自动扶梯安全规范》
ASME A17.1, 'Safety Code for Elevators and Escalators'
#电梯 #安全钳 #限速器
冰箱门封条为什么是带磁的？
Why is the fridge door gasket magnetic?
门封里的磁条让箱门一靠就吸住并压紧软胶条，堵住缝隙减少冷气漏出和结露。
A magnetic strip snaps the door shut and compresses the seal to stop cold-air leaks and condensation.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#冰箱 #磁封 #密封
洗碗机为什么据说比手洗还省水？
Why is a dishwasher said to use less water than hand washing?
它用泵把少量水加压喷成多方位水柱反复冲刷并循环使用，总用水量常低于长流水手洗；高温水也更易去油。
It pressurizes and recirculates a small amount of water through spray arms, often using less than open-tap hand washing.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#洗碗机 #循环水 #省水
滚筒洗衣机加热洗为什么比冷水洗更干净？
Why does a warm wash clean better than a cold one?
温水加快洗衣粉中酶的活性并软化油污，让污渍更容易从纤维脱离；但高温也会伤某些面料，所以分档选择。
Warm water boosts enzyme activity and softens grease so stains detach more easily, though high heat can damage fabrics.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
Cengel，《传热与传质》（第5版）
Cengel, 'Heat and Mass Transfer' (5th ed.)
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL20333053W：Heat and Mass Transfer
#洗衣机 #酶 #水温
电吹风吹出来的风为什么是热的？
Why is the air from a hair dryer hot?
里面的电热丝通电发热，小风扇把空气吹过发热丝带走热量；负离子款只是额外加一束带电粒子减少静电。
A heating element warms air pulled through by a fan; ionic models just add charged particles to reduce static.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04 · 3 条独立证据
来源 · Source
Cengel，《工程热力学：一种工程方法》（第9版）
Cengel, 'Thermodynamics: An Engineering Approach' (9th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-259-27989-8 (9th ed., McGraw-Hill) · 核验依据 2 ISBN 9781260116106 (2018) · 核验依据 3 ISBN 9780665590955 (2002)
#电吹风 #电热丝 #风扇
停电的时候冰箱里的食物会坏吗?冰箱是怎么制冷的?
Does food spoil in a blackout? How does a fridge make things cold anyway?
冰箱里有一套搬运热的系统:制冷剂在管子里循环,在冷冻室吸走热量变成气体,再到背面的管子把热散给房间空气——它不是制造冷,而是把里面的热搬到外面。短时间停电没关系:关紧箱门,冰块帮着保温,四小时内食物依然安全;堆满东西的冰箱比空冰箱更扛饿。
A fridge moves heat rather than making cold: refrigerant cycles through pipes, soaking up heat inside then releasing it from coils at the back into your kitchen. Short blackouts are fine — keep doors shut and ice blocks help; four hours stays safe, and a full fridge holds cold longer than an empty one.
难度 进阶 · 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
韩启德总主编,《十万个为什么》第六版,少年儿童出版社,2013
Ten Thousand Whys, 6th ed., editor-in-chief Han Qide, 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
#冰箱 #制冷原理 #停电应对
电熨斗怎么知道该加热到什么温度？
How does an iron know what temperature to hold?
旋钮设定压力让双金属片在不同温度弯曲并断开触点，达到目标温度就断电、降温后再接通，从而恒温。
A dial sets how far a bimetal strip must bend to open the contact, cycling power to hold a set temperature.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04 · 3 条独立证据
来源 · Source
Cengel，《工程热力学：一种工程方法》（第9版）
Cengel, 'Thermodynamics: An Engineering Approach' (9th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-259-27989-8 (9th ed., McGraw-Hill) · 核验依据 2 ISBN 9781260116106 (2018) · 核验依据 3 ISBN 9780665590955 (2002)
#电熨斗 #双金属 #恒温
空调室外机为什么会滴水？
Why does the outdoor AC unit drip water?
制冷时室内机蒸发器很冷，空气中的水汽冷凝成水珠排出；室外机滴水通常是排出的冷凝水或化霜水，属正常现象。
Cooling condenses indoor humidity into water that drains out; outdoor drips are usually that condensate or defrost water.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-04 · 3 条独立证据
来源 · Source
Cengel，《工程热力学：一种工程方法》（第9版）
Cengel, 'Thermodynamics: An Engineering Approach' (9th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-259-27989-8 (9th ed., McGraw-Hill) · 核验依据 2 ISBN 9781260116106 (2018) · 核验依据 3 ISBN 9780665590955 (2002)
#空调 #冷凝水 #制冷
吸尘器看不见吸力，它靠什么把灰尘吸起来？
A vacuum has no visible suction, so what pulls the dust in?
电机带动叶轮在腔内制造低于大气压的负压，外界空气裹着灰尘从吸口被压进来，滤网把灰留下。
A fast impeller makes lower pressure inside, so outside air rushes in carrying dust through a filter that traps it.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#吸尘器 #负压 #风机
电风扇吹着好凉快，可房间里的温度并没有降下来，这是为什么？
A fan feels wonderfully cool, yet the room temperature does not drop — why?
风扇只是把空气搅动起来，它自己的电动机还在把电变成热，房间温度其实会略微上升。人觉得凉，是因为流动的空气把皮肤旁边被体温烘热的空气层吹走，并加快汗液蒸发，而蒸发要带走大量热量，皮肤的散热效率就提高了。所以风扇在闷热、汗不容易蒸发的时候最管用；空调则是真的把屋里的热搬到室外去，温度计上的数字才会往下走。
A fan only stirs the air and its motor even adds a little heat, so room temperature edges up rather than down. People feel cooler because moving air sweeps away the warm film of air hugging the skin and speeds up sweat evaporation, and evaporation carries off a lot of heat, raising the skin's cooling rate. That is why a fan helps most in muggy stillness, whereas an air conditioner genuinely moves heat out of the room, which is what makes the thermometer fall.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
ASHRAE Handbook—Fundamentals（2021），第9章 热舒适
ASHRAE Handbook—Fundamentals (2021), Chapter 9, Thermal Comfort
独立核验依据 · Independent verification: 核验依据 1 ISBN 9781947192898 (2021)
#风扇 #对流散热 #汗液蒸发
LED灯为什么比老式白炽灯省电又耐烧？
Why do LEDs save power and last longer than old bulbs?
白炽灯靠灯丝发热发光，约九成能量变热；LED用电致发光直接出光、发热少，同样亮度用电更少、寿命更长。
Incandescents waste about 90% as heat; LEDs emit light directly with little heat, so they use less power and last longer.
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
Streetman & Banerjee，《固态电子器件》（第7版）
Streetman & Banerjee, 'Solid State Electronic Devices' (7th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9787121315657（豆瓣书目条目: 固态电子器件） · 核验依据 2 OPENLIBRARY 标识 /works/OL34943756W：Solid State Electronic
#LED #电致发光 #节能
电热水壶烧开后，为什么能自己断电不再烧？
Why does a kettle switch itself off after boiling?
壶盖下的蒸汽通道把沸腾蒸汽引到双金属片或蒸汽开关，受热变形切断电源；水没开时温度不够不会跳。
Boiling steam reaches a bimetal or steam switch that bends and cuts power; below boiling it stays on.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#电水壶 #蒸汽开关 #双金属
电灯为什么会亮?按一下开关发生了什么?
What makes lamps light up when we flip the switch?
电线里住着看不见的小小电流精灵。开关一按,路就通了,精灵们飞快地跑过灯泡里的细丝,丝一发热就发出光来。再按一下,门关上,灯就熄了。所以不能把手指伸进插座哦!
Tiny electric helpers live inside wires. Flip the switch and the road opens: they race through the bulb's thin filament, which glows hot with light. Flip again, the door closes and the lamp sleeps. Never put fingers in sockets!
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
David Macaulay,《The Way Things Work》,Houghton Mifflin,1988
David Macaulay, The Way Things Work, Houghton Mifflin, 1988
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL15130328W：The Way Things Work（按标
#电灯 #开关 #用电安全
洗衣机脱水时为什么衣服不会飞出去，水却被甩走了？
When a washer spins, why don't clothes fly out while water is thrown away?
滚筒高速旋转产生离心力把水从衣服和筒壁小孔甩出，衣服被筒壁挡在里面；若不平衡，传感器会降速纠偏。
The spinning drum's centrifugal force pushes water out through tiny holes while the wall keeps clothes in; an imbalance sensor slows it to rebalance.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-03
来源 · Source
Serway & Jewett，《科学家与工程师的物理学》（第10版）
Serway & Jewett, 'Physics for Scientists and Engineers' (10th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-1-337-55327-8
#家电 #离心力 #洗衣机