电动势与串联

A reformulation of classical mechanics based on the principle of stationary action. It uses a scalar quantity called the Lagrangian, defined as kinetic energy minus potential energy ([latex]L = T - V[/latex]). The equations of motion are derived from the Euler-Lagrange equation, [latex]\frac{d}{dt} \left( \frac{\partial L}{\partial \dot{q}_i} \right) - \frac{\partial L}{\partial q_i} = 0[/latex], using generalized coordinates, which simplifies analysis of complex systems with constraints.

Galvanic corrosion is an electrochemical process where one metal corrodes preferentially when in electrical contact with another in the presence of an electrolyte. This occurs because the dissimilar metals create a bimetallic couple, with the less noble (more active) metal acting as the anode and corroding, while the more noble metal acts as the cathode.

它是第一个电池，通过堆叠成对的不同金属片（例如锌和铜），并用浸过盐水的布隔开，从而产生直流电。每对金属片构成一个原电池，将它们串联起来可以提高总电压。这种结构首次实现了化学能向电能的连续转化，为现代电化学奠定了基础。

菲涅尔区是位于发射器和接收器之间的一系列共焦长椭球区域之一。主菲涅尔区的边界是一个椭球面，在该椭球面上，从发射器到接收器表面某一点的路径长度比直接路径长半个波长，从而导致180度的相位偏移。

这是描述连续力学中运动的两种方法：

• 拉格朗日规范遵循单个材料粒子，跟踪它们随时间的变化，就像观察交通中的特定汽车一样
• 欧拉规范关注空间中的固定点，观察通过这些点的任何粒子的属性（速度、密度），就像交通摄像头观察固定交叉路口一样。

固体力学是连续介质力学的一个分支，研究固体材料的行为，特别是它们在力、温度变化或其他外部载荷作用下的运动和变形。它是工程结构设计和分析的基础。关键领域包括弹性力学（可恢复变形）、塑性力学（永久变形）和断裂力学（裂纹的萌生和扩展）。

Electromotive force ([latex]\mathcal{E}[/latex]) is the work done per unit of electric charge by a non-electrical source, such as a battery or generator. Despite its name, it is not a mechanical force but an electric potential, measured in volts. It represents the energy converted from another form (chemical, mechanical) into electrical energy as a charge traverses the source.

The electric current in a Voltaic pile is produced by a redox reaction. At the zinc anode, zinc metal is oxidized, releasing two electrons per atom ([latex]Zn \rightarrow Zn^{2+} + 2e^{-}[/latex]). These electrons travel through the external circuit to the copper cathode. There, hydrogen ions from the aqueous electrolyte are reduced, forming hydrogen gas ([latex]2H^{+} + 2e^{-} \rightarrow H_2[/latex]).

Absolute humidity ([latex]d_v[/latex]) is the total mass of water vapor ([latex]m_{H_2O}[/latex]) present in a given volume of air ([latex]V_{air}[/latex]). It is expressed as grams of water vapor per cubic meter of air ([latex]g/m^3[/latex]). The formula is [latex]d_v = \frac{m_{H_2O}}{V_{air}}[/latex]. Unlike relative humidity, it is not dependent on the air's temperature, but it is affected by changes in air pressure or volume.

1801年，约翰·威廉·里特（Johann Wilhelm Ritter）观察到，太阳光谱中紫色端以外的不可见射线比紫光本身更快地使浸有氯化银的纸张变暗。这证明了可见光谱之外存在一种光，他将其命名为“氧化射线”，以与前一年发现的“热射线”（红外线）相对照。