solid angle: meaning, definition, pronunciation and examples
Very LowHighly Technical/Scientific
Quick answer
What does “solid angle” mean?
The three-dimensional analog of a planar angle, measured in steradians, representing the amount of field of view an object covers from a given point.
Audio
Pronunciation
Definition
Meaning and Definition
The three-dimensional analog of a planar angle, measured in steradians, representing the amount of field of view an object covers from a given point.
In physics, mathematics, and astronomy, it is a measure of how large an object appears to an observer at a point, crucial for calculations involving radiant flux, luminosity, and probability in three dimensions.
Dialectal Variation
British vs American Usage
Differences
No lexical or spelling differences. Pronunciations differ minimally (see IPA).
Connotations
None beyond the strict technical meaning.
Frequency
Extremely rare in general discourse in both varieties. Used exclusively in advanced scientific contexts.
Grammar
How to Use “solid angle” in a Sentence
[Object] subtends a solid angle of X steradians at [Point].The [Detector] covers a solid angle of...The integral is taken over the full solid angle.Vocabulary
Collocations
Examples
Examples of “solid angle” in a Sentence
verb
British English
- The detector is designed to subtend the largest possible solid angle.
American English
- The aperture subtends a solid angle of about 0.5 steradians.
adverb
British English
- The flux was integrated solid-angle-wise.
American English
- The measurement is performed solid-angle-resolved.
adjective
British English
- The solid-angle distribution was not isotropic.
American English
- We need a high solid-angle coverage detector.
Usage
Meaning in Context
Business
Never used.
Academic
Exclusively in advanced physics, mathematics, astronomy, and engineering textbooks/research, particularly in optics, radiometry, nuclear physics, and geometry.
Everyday
Virtually never used.
Technical
Core term in fields dealing with radiation, flux, particle detectors, antenna theory, and spherical geometry.
Vocabulary
Synonyms of “solid angle”
Strong
Neutral
Weak
Vocabulary
Antonyms of “solid angle”
Watch out
Common Mistakes When Using “solid angle”
- Confusing it with a planar (2D) angle. Mispronouncing 'solid' to mean 'firm'. Using degrees instead of steradians.
FAQ
Frequently Asked Questions
No, a planar (2D) angle is measured in degrees or radians. A solid angle (3D) is measured in steradians (sr).
It means an object, as seen from a specific point, covers or defines a certain solid angle. For example, the Moon subtends a very small solid angle from Earth.
The solid angle of a full sphere, encompassing all directions from a point, is 4π steradians.
You would only encounter it in advanced scientific or engineering contexts, such as designing lighting systems, analyzing telescope data, calculating radiation doses, or simulating particle physics experiments.
The three-dimensional analog of a planar angle, measured in steradians, representing the amount of field of view an object covers from a given point.
Solid angle is usually highly technical/scientific in register.
Solid angle: in British English it is pronounced /ˌsɒl.ɪd ˈæŋ.ɡəl/, and in American English it is pronounced /ˌsɑː.lɪd ˈæŋ.ɡəl/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “None. The term is purely literal.”
Learning
Memory Aids
Mnemonic
Think of a **solid** ice-cream **cone**: the point is at your eye, and the cone's opening defines a patch on the 'sky'—that's your **solid angle**. The fatter the cone, the larger the solid angle.
Conceptual Metaphor
PATCH OF SKY: The solid angle is conceptually a 'patch' or 'area' on an imaginary sphere centered at the observation point.
Practice
Quiz
What is the unit of measurement for a solid angle?