欧姆导体和非欧姆导体

In a system at thermodynamic equilibrium, the electrochemical potential, [latex]\bar{\mu}_i[/latex], for any given charged species `i` must be uniform throughout all phases. If a gradient exists ([latex]\nabla \bar{\mu}_i \neq 0[/latex]), ions will spontaneously move from regions of higher potential to lower potential, creating a current or flux, until this gradient is eliminated and equilibrium is re-established.

铝热剂具有极高的活化能，使其在室温下稳定且难以点燃。点火需要达到约 1,300 °C (2,400 °F) 的温度。这通常不是通过直接火焰来实现的，而是借助中间高温引发剂（例如燃烧的镁带或专门设计的烟火引信）来实现的，这些引发剂可提供引发反应所需的局部能量。

Planck's relation is a fundamental equation in quantum mechanics that quantifies the energy of a single photon. The formula is [latex]E = h\nu[/latex], where [latex]E[/latex] is the energy of the photon, [latex]\nu[/latex] (nu) is its frequency, and [latex]h[/latex] is the Planck constant. This relation establishes the particle-like nature of light, showing that its energy is quantized in discrete packets, or quanta.

大闪蝶翅膀上那鲜艳夺目的蓝色并非由色素产生，而是由结构性着色所致。翅膀上覆盖着形似微型圣诞树的纳米结构，这些结构通过薄膜干涉和衍射选择性地反射蓝光，同时吸收其他波长的光，从而创造出一种强烈的、随角度变化的色彩。

氧平衡 (OB%) 是衡量炸药氧化程度的指标。如果一个炸药分子含有足够的氧，能够将其所有碳转化为二氧化碳，所有氢转化为水，则其氧平衡为零。正的氧平衡表示氧过剩，而负的氧平衡则表示氧不足，这会影响能量输出和副产物。

镍镉电池由瓦尔德马尔·荣格纳（Waldemar Jungner）于1899年发明，以氢氧化镍（NiO(OH)）为正极，以金属镉（Cd）为负极，并使用氢氧化钾（KOH）等碱性电解质。镍镉电池以其较长的循环寿命和良好的低温性能而闻名，但也存在记忆效应和镉的毒性问题。

The absolute electrochemical potential of a single electrode cannot be measured. Instead, potentials are measured relative to a universally accepted reference. The Standard Hydrogen Electrode (SHE) is the primary reference, assigned a potential of exactly 0 volts under standard conditions (1 M [latex]H^+[/latex] concentration, 1 bar [latex]H_2[/latex] gas, 298 K). All other standard electrode potentials are reported relative to this zero point.

升华是一种用于纯化化合物（尤其是挥发性固体）的实验室技术。将不纯的固体缓慢加热（通常在减压条件下），使其直接升华为气体。然后，该气体以纯固体的形式沉积在冷却的表面上（称为冷指），而非挥发性杂质则留在原始容器中。

色温是可见光的一种特性，用于测量其色调，范围从暖色（淡黄色）到冷色（淡蓝色）。色温定义为理想黑体辐射体（其辐射光的色调与光源的色调相似）的温度。其测量单位为开尔文 (K)。

The principles of Mohr's circle can also be directly applied to analyze the two-dimensional state of strain at a point. By replacing normal stress ([latex]\sigma[/latex]) with normal strain ([latex]\epsilon[/latex]) and shear stress ([latex]\tau[/latex]) with half the shear strain ([latex]\gamma/2[/latex]), an analogous circle can be constructed. This graphical tool helps determine principal strains and the maximum shear strain.

The Galilean cannon demonstrates velocity multiplication through sequential, one-dimensional elastic collisions. When a stack of balls with decreasing mass is dropped, the bottom ball rebounds and collides with the one above. In an idealized case where a large mass [latex]m_1[/latex] rebounds at velocity [latex]v[/latex] and hits a much smaller mass [latex]m_2[/latex] moving down at [latex]v[/latex], the smaller mass is propelled upwards at nearly [latex]3v[/latex].

The thermal efficiency ([latex]\eta_{th}[/latex]) of an ideal Otto cycle is a function of the compression ratio ([latex]r[/latex]) and the specific heat ratio ([latex]\gamma[/latex]) of the working fluid. The formula is [latex]\eta_{th} = 1 - \frac{1}{r^{\gamma-1}}[/latex]. This equation shows that efficiency increases with the compression ratio, providing a fundamental principle for engine design and performance optimization.