sentence: Ideal meters have no effect on the state variables of the system they are measuring.
sentences_before: It is important that these two types of instruments are distinct. A meter does not perform its task accurately if it behaves like a reservoir of the state variable it is trying to measure. If, for example, a thermometer, were to act as a temperature reservoir it would alter the temperature of the system being measured, and the reading would be incorrect.
concept_name: ideal meter
headings: Thermal physics Thermodynamic instruments
categories: Thermodynamics