Qh

Qh is a two-character sequence that appears in different domains with no single universal meaning. The interpretation of Qh depends on context and discipline.

In thermodynamics and heat transfer, Q_h commonly denotes the quantity of heat transferred to a hot reservoir during a process or cycle. It is often contrasted with Q_c, the heat exchanged with a cold reservoir. Analyses of heat engines, refrigerators, and heat pumps frequently use Q_h together with other variables such as work and entropy to describe energy transfers.

In linguistics and orthography, the digraph “qh” appears in some writing systems as a single grapheme representing a consonantal sound. The exact pronunciation and phonetic value of this unit vary by language, so its function is language-specific rather than universal.

In broader mathematical and scientific notation, Q_h can occur as a quantity labeled with a subscript h. The subscript h is defined within each source and can indicate a particular case, parameter, component, or element in a decomposition. Its meaning is context-dependent and not standardized across disciplines.

Because Qh is not tied to one canonical concept, references to Qh should clarify the domain and the precise definition used in that source.

See also Q, H, subscripts in mathematical notation.