Spänning

Spänning is a Swedish term with several closely related meanings. In science and engineering it is used for electrical potential difference, for internal forces within a material under load, and in everyday language it denotes tension or suspense.

In electricity, spänning (elektrisk spänning) is the electric potential difference between two points, describing the driving force that pushes electric charges to move in a circuit. It is measured in volts (V) and defined as the work done per unit charge by the electric field. Direct current (DC) provides a constant spänning, while alternating current (AC) varies periodically. For AC, the rms (root-mean-square) value is used for practical calculations, and the peak value is used in instantaneous analyses. Spänning arises from sources such as batteries, power grids, or generators and is read with a voltmeter. Safety regarding insulation and voltage ratings is an important design consideration.

In mechanics, spänning denotes the internal distribution of forces within a material under load, i.e., stress. It is usually expressed as force per unit area and measured in pascals (Pa). Tensile spänning pulls matter apart; compressive spänning pushes it together. The relation to deformation is described by constitutive laws; for elastic materials, stress is proportional to strain via Hooke's law, sigma = E * epsilon, where E is Young's modulus. Materials have yield strength and ultimate tensile strength, which constrain allowable spännings in engineering design.

In everyday language, spänning also refers to emotional or dramatic tension, such as suspense in a story or pressure in a situation. In psychology and culture, it describes arousal arising from anticipation or conflict.