Lämpötilakertoimilla

Lämpötilakertoimilla, or temperature coefficients, describe how a physical property of a substance or device changes with temperature. This property can be electrical resistance, voltage, capacitance, magnetic permeability, or many other measurable quantities. Temperature coefficients are typically expressed as a ratio of the fractional change in the property per unit change in temperature.

For electrical resistance, the temperature coefficient (often denoted by alpha, α) indicates how much the resistance increases or decreases for every degree Celsius (or Kelvin) change in temperature. Materials with a positive temperature coefficient, like most metals, see their resistance increase as temperature rises. Conversely, materials with a negative temperature coefficient, such as semiconductors and some insulators, exhibit decreasing resistance with increasing temperature.

Understanding temperature coefficients is crucial in various engineering applications. For instance, in electronic circuits, components with significant temperature coefficients can lead to performance drift or instability. Engineers often select materials or design circuits to compensate for these temperature-dependent variations. Thermistors are a prime example of devices that exploit a large negative temperature coefficient for temperature sensing. Precision resistors used in sensitive measurement equipment are often made from materials with very low temperature coefficients to minimize errors. The concept also applies to mechanical components, where thermal expansion and contraction are described by coefficients of thermal expansion, a related but distinct phenomenon.