🔬 科学与工程Science & Engineering
欧姆定律计算器Ohm's Law Calculator
填写电压、电流、电阻、功率中的任意两个，计算其余两个（V=IR，P=VI）。Enter any two of voltage, current, resistance and power to get the other two (V = IR, P = VI).
色环电阻计算器Resistor Color Code Calculator
选择 4 环或 5 环电阻的颜色，计算阻值、误差范围，并显示色环图示。Pick the bands of a 4- or 5-band resistor to get resistance and tolerance, with a drawing.
分压电路计算器Voltage Divider Calculator
计算电阻分压电路的输出电压：Vout = Vin × R2 / (R1 + R2)，以及电流和功耗。Output voltage of a resistor divider: Vout = Vin × R2 / (R1 + R2), plus current and power.
LED 限流电阻计算器LED Resistor Calculator
根据电源电压、LED 正向电压和电流计算限流电阻值、功率，并推荐 E24 标准阻值。Current-limiting resistor for LEDs from supply voltage, forward voltage and current, with the nearest E24 value.
速度距离时间计算器Speed, Distance & Time Calculator
填写速度、距离、时间中的任意两个，计算第三个。Enter any two of speed, distance and time to calculate the third.
密度质量体积计算器Density, Mass & Volume Calculator
填写密度、质量、体积中的任意两个，计算第三个（ρ = m / V），并对照常见物质密度。Enter any two of density, mass and volume to find the third (ρ = m/V), with common material densities.
动能势能计算器Kinetic & Potential Energy Calculator
计算物体的动能（½mv²）和重力势能（mgh），以及从该高度落下时的着地速度。Kinetic energy (½mv²), gravitational potential energy (mgh) and impact speed from that height.
抛体运动计算器Projectile Motion Calculator
根据初速度、发射角和初始高度计算射程、最大高度和飞行时间（忽略空气阻力）。Range, maximum height and flight time from launch speed, angle and height (no air resistance).
半衰期计算器Half-Life Calculator
计算放射性衰变后剩余量：N = N₀ × (1/2)^(t/T)，或由剩余比例反推经过时间。Remaining quantity after decay, N = N₀ × (½)^(t/T), or the time elapsed from the remaining fraction.
摩尔质量计算器Molar Mass Calculator
输入化学式（如 H2O、Ca(OH)2、CuSO4·5H2O），计算摩尔质量和各元素质量分数。Molar mass and element mass percentages from a chemical formula like H2O, Ca(OH)2 or CuSO4·5H2O.
理想气体状态方程计算器Ideal Gas Law Calculator
PV = nRT：填写压强、体积、物质的量、温度中的三个，计算第四个。PV = nRT: enter three of pressure, volume, moles and temperature to solve for the fourth.
波长频率能量换算Wavelength, Frequency & Photon Energy
电磁波波长、频率和光子能量互算（c = λf，E = hf），并显示所属波段。Convert between wavelength, frequency and photon energy (c = λf, E = hf) and show the band.
溶液稀释计算器（C1V1=C2V2）Dilution Calculator (C1V1 = C2V2)
按 C1V1 = C2V2 计算溶液稀释所需体积：留空一个值即可求解。Solve C1V1 = C2V2 for any one unknown — how much stock and diluent to use.
pH 值计算器pH Calculator
由氢离子浓度 [H⁺]、氢氧根浓度 [OH⁻]、pH 或 pOH 中任意一个，计算其余值（25°C）。From [H⁺], [OH⁻], pH or pOH, calculate the others (at 25 °C).
在其他星球上的体重Weight on Other Planets
输入你在地球上的体重，看看在月球、火星、木星等星球上有多重。See what you'd weigh on the Moon, Mars, Jupiter and other planets.
电容代码换算Capacitor Code Calculator
把电容上的 3 位数字代码（如 104、472）换算为 pF/nF/µF，或反向求代码。Decode 3-digit capacitor codes (e.g. 104, 472) to pF/nF/µF, or find the code for a value.
AWG 线规换算AWG Wire Gauge Converter
美国线规 AWG 与线径(mm)、截面积(mm²)互相换算，并显示参考电阻。Convert AWG wire gauge to diameter (mm), cross-section (mm²) and resistance per km.