Physics glossary — letter F
4 physics terms starting with F.
- Fermi Level
- The energy level that separates occupied from unoccupied electron states at very low temperature.
- Fermion
- A particle with half-integer spin that obeys the Pauli exclusion principle.
- Focal Length
- The distance from a lens or mirror to the point where parallel rays converge or appear to diverge from.
- Free Body Diagram
- A sketch showing all forces acting on an isolated object.
More from the library
How to use the F glossary terms
This letter page is a quick route into related physics vocabulary, but the best use is active comparison. After reading a definition, ask what physical quantity is being described, what units are involved, and which equation or model normally uses the term. A glossary entry becomes more useful when it is tied to a formula, example, or calculator.
Many physics words look familiar from everyday language but have stricter meanings in a problem. Words such as action, field, power, pressure, state, or work can change meaning depending on whether the page is discussing mechanics, thermodynamics, electromagnetism, waves, or quantum theory. When a term appears in an equation, use the variable table and units to pin down the intended meaning.
Study links for this letter
For definitions that involve a measurable quantity, check the formula library and calculator library. For broader conceptual terms, follow the relevant topic hub such as classical mechanics, quantum physics, thermodynamics, waves and optics, or electromagnetism.
When reviewing for an exam, write one sentence that connects the term to a real situation. For example, a term may describe a force, a conservation law, a material property, a wave behavior, a measurement method, or a boundary condition. That sentence is often the difference between recognizing a word and being able to use it in a calculation.
Review method
For each term, make a quick three-part note: the plain-language meaning, the symbol or equation if one is commonly used, and one example where the term appears in a real physics problem. This prevents glossary study from becoming memorization without application.
If two terms sound similar, compare them directly. Ask whether they describe a quantity, a process, a law, a material property, a measurement, or a point in a wave or field. That comparison helps when a problem uses familiar words in a stricter technical sense.
After reviewing this letter, return to the main glossary and choose a neighboring letter. Physics vocabulary is highly connected, so terms from one letter often depend on ideas introduced elsewhere.
For compact letters with only a few entries, spend the extra minute tracing each term to a formula page, calculator, or topic hub. That small step turns a short vocabulary list into a practical revision path.