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1 Primary & Middle School Physics1–9 年级在线 2 High School Physics10–12 年级在线 3 University Physics — Year 1本科一年级在线 4 University Physics — Year 2本科二年级在线 5 University Physics — Year 3本科三年级在线

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1 Markets I: The Ecosystem and Exchange-Traded Markets市场在线 2 Markets II: Rates, FX and Credit市场在线 3 Markets III: Commodities, Energy and Crypto市场在线 4 Quantitative Methods方法在线 5 Derivatives and Volatility衍生品在线 6 Rates, Credit, XVA and Risk利率、信用与风险在线 7 Research Craft: Predictors, Backtests, Measurement, Portfolios研究在线 8 Strategies I: Equities and Futures策略在线 9 Strategies II: Volatility, Relative Value, Macro and the Bank Desks策略在线 10 Microstructure and Execution交易执行在线 11 Market Making and High-Frequency Trading做市在线 12 Machine Learning for Markets机器学习在线 13 Low-Latency Software技术在线 14 Networks, Hardware and Trading Infrastructure技术在线 15 Research, Data and Risk Platforms技术在线 16 The Desk and the Firm公司运营在线 17 The Industry: Firms, Roles and Careers职业发展在线 18 Interviews I: Maths, Probability and Speed职业发展在线 19 Interviews II: Markets, Trading Games and the Final Round职业发展在线 20 Interviews III: Code职业发展在线

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Physics · 术语表

什么是 Electrostatic field？

Definition 26.4 University Physics — Year 1 · 第 26 章 — Electrostatics: Field and Gauss’s Law

A distribution of charges at rest creates at every point $M$ of space an electric field $\vect E(M)$ , defined by the force it exerts on a test charge $q$ placed at $M$ : $\vect F = q\vect E(M)$ ( $\mathrm{V}/\mathrm{m}$ $=$ $\mathrm{N}/\mathrm{C}$ ). A point charge $q_1$ at $O$ creates

\vect E(M) = \frac{q_1}{4\pi\varepsilon_0 r^2}\,\vect e_r , \qquad r = OM ,

radial, outward for $q_1 > 0$ ; a distribution creates the vector sum of the fields of its elements. A field line is a curve tangent at each point to $\vect E$ , oriented along it.

Field lines of two opposite charges (left) and of two equal positive charges (right). Lines start on + and end on - or at infinity; on the right they repel each other and the field vanishes at the midpoint, where no line passes. — Field lines of two opposite charges (left) and of two equal positive charges (right). Lines start on $+$ and end on $-$ or at infinity; on the right they repel each other and the field vanishes at the midpoint, where no line passes.

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